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  • 1
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    Innovative Booster for Dynamic Installation of OMNI-Max Anchor in Clay: Numerical Modeling (2022)
    ASCE (American Society of Civil Engineers)
    In:  Journal of Waterway, Port, Coastal, and Ocean Engineering, 148 (1).
    Details
    Publication Date: 2021-12-13
    Description: An innovative booster is proposed with the aim of increasing the final penetration depth of the OMNI-Max anchor in the clayey seabed with high strength gradient. The booster is attached to the tail of the OMNI-Max anchor, which is beneficial in improving both gravitational and kinetic energies of the hybrid anchor (i.e., booster + OMNI-Max anchor) during installation and can be retrieved after dynamic installation. The present study carried out two categories of large deformation numerical analyses to simulate the dynamic penetration processes of OMNI-Max anchors and hybrid anchors in normally consolidated and lightly overconsolidated clay. The coupled Eulerian–Lagrangian (CEL) approach was used to investigate the effects of impact velocity, booster weight, and soil strength characteristics (including the strain-rate behavior, the strain-softening behavior, and the undrained shear strength) on the final penetration depth of the anchor. Due to the limitations of the CEL approach in simulating the adhesion friction at the anchor–soil interface, a thin layer region method coupled in the computational fluid dynamics (CFD) approach was used to investigate the effect of the friction coefficient at the anchor–soil interface on the final penetration depth of the anchor. Based on numerical simulation results, a comprehensive prediction model based on the anchor total energy was established to rapidly predict the final penetration depth of the OMNI-Max anchor and the hybrid anchor by considering the strain-rate effect, strain-softening effect, and friction coefficient at the anchor–soil interface.
    Type: Article , PeerReviewed
    Format: text
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  • 2
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    GIS-based analysis of a geotechnical-geological 3D model of periglacial Quaternary rocks in the southern Leine valley, Lower Saxony (2021)
    Details
    Publication Date: 2021-03-29
    Description: Geometric 3D models are a very efficient tool to visualize geological units and structural features that have been presented before just in two dimensions on maps or cross-sections. Most of the information of 3D models is presented as 3D views, virtual wells or horizontal or vertical cross-sections. However, are there further options to transfer as much as possible of the complex information of a 3D model in an adequate way to the user? Is it useful and promising to analyse 3D objects like surfaces or volumes in GIS software? In our investigation we performed a GIS based analysis of an existing geotechnical-geological 3D model of periglacial sediments. The two steps were multiple raster calculations to create geotechnical maps and a digital analysis of surface parameters based on geomorphological techniques and statistics. The investigation area is located in southern Lower Saxony and covers the city of Goettingen and surrounding regions within the valley of the river Leine. The valley is filled by unconsolidated, periglacial sediments of Quaternary age with a variable thickness ranging from 1 to 70 m. The analysed 3D model was constructed with GoCAD in a former project (Nix et al. 2009). The model is based on a heterogenous dataset comprising well data, thematic maps, and outcrop descriptions. Finally, the surfaces and volumes of the following units were modelled, with a special focus on their different geotechnical properties: (1) anthropogenic material, (2) floodplain and slope deposits, (3) freshwater limestone, peat and organic clay, (4) loess, displaced loess, and loess loam, (5) fluvial gravel, (6) outwash fan material, (7) solifluction material, (8) mixed, hetereougenous fillings of subrosion sinks and (9) the surface of the underlying hardrocks. Each top and bottom surface of the Gocad volumes was exported as raster file with additional information stored in an associated attribute table. In ArcGIS various geoprocessing tools were used to calculate and analyse these rasters and to develope thematic geotechnical and geological maps. The geomorphological analysis was subdivided in several steps. Firstly, the surfaces were described visually, concerning their outline, shape and distribution, as well as superficial structures like distinct edges, holes, channels. Secondarily, descriptive statistic parameters of thickness, area and elevation of each surface were calculated. Thirdly, geoprocessing tools of the Spatial Analyst were performed on each surface. Finally, several surfaces were combined to analyse them together, calculating ratios and overlay combinations. Seven thematical geoengineering and geological maps were created, each of them presenting one portion of the three-dimensional dataset: Map of the stratigraphy and depth of the Quaternary base, Map of the thickness of the Quaternary sediments, Distribution map of model units 1 m below ground level, Distribution map of model units 2 m below ground level, Maps of types of different foundation soils, Distribution map of sediments with low loading capacity and Map of distribution and quality of the wells. While the map creation focused on the geotechnical aspects of the model, the applied geomorphological analysis revealed various parameters and values that are related to the geological formation of the model units. Despite the complex dataset represented by the analysed 3D model, thematical information could be transfered into 2D as thematic maps. Some geological characteristics and parameters of the model units were extracted by the descriptive and GIS-based analysis. References Nix, T., Wagner, B., Lange, T. , Fritz, J., Sauter, M. (2009): 3D-Baugrundmodell der quartären Sedimente des Leinetals bei Göttingen. – 17. Tagung für Ingenieurgeologie, S. 223-227, Zittau
    Description: poster
    Keywords: 3D model ; Quaternary ; Lower Saxony ; geotechnical ; GIS ; FID-GEO-DE-7
    Language: English
    Type: conferencePaper
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  • 3
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    Tectono‐Magmatic, Sedimentary, and Hydrothermal History of Arsinoes and Pyrrhae Chaos, Mars (2021)
    Details
    Publication Date: 2021-07-04
    Description: Arsinoes and Pyrrhae Chaos are two adjacent chaotic terrains located east of Valles Marineris and west of Arabia Terra, on Mars. In this work, we produced a morpho‐stratigraphic map of the area, characterized by a volcanic bedrock disrupted into polygonal mesas and knobs (Chaotic Terrain Unit) and two nondisrupted units. The latter present a spectral variation, likely associated with hydrated minerals, and they are here interpreted as sedimentary units. The reconstructed geological history of the area starts with the emplacement of the basaltic bedrock, followed by the collapse that caused the formation of the chaotic terrains. Since evidences of volcano‐tectonic activity are widespread across the area (e.g., fissure vents/graben, radial and concentric systems of faults, y‐shaped conjunctions, lava flows, and pit chains), and an intricate system of lava conduits is hypothesized for the occurrence of such features, we propose the possibility that the whole collapse was caused primarily by volcano‐tectonic processes. In a late stage, after the end of the volcano‐tectonic activity, a lacustrine/evaporitic depositional environment could have set, with the deposition of the nondisrupted units. The hydrated minerals found in the periphery of the Chaos could be the result of hydrothermal alteration of the basaltic bedrock.
    Description: Plain Language Summary: Chaotic terrains are peculiar features on Mars. They consist of broad regions characterized by a variable surface disruption pattern of large polygonal blocks. Formation scenarios in the literature have always included a collapse, possibly caused by a range of processes, all including water or hydrated compounds (magma‐ice interactions, melting of buried ice, groundwater pressure, etc.). In this work, we propose volcano‐tectonic processes as mechanism of formation for closed chaotic terrains. Additionally, our mineralogical analyses suggest that during a late stage of the volcanic activity, a hydrothermal system could have set. In such scenario, hot water would have risen from the subsurface through fractures created by the volcanic activity, evolving from eruptive to hydrothermal. However, water would not have been directly involved in the initial collapse that formed the chaos.
    Description: Key Points: We produced a morpho‐stratigraphic map of Arsinoes and Pyrrhae Chaos, including the volcanic grabens occurring throughout the study area. Spectral analyses of the light‐toned deposits provide clues for sedimentary and hydrothermal minerals; spectral analyses of the bedrock are indicative of basaltic compositions. The observed volcano‐tectonic surface features and the lack of evidences of any fluvial activity suggest that magmatic processes might be primarily responsible for the collapse of the chaotic terrain.
    Description: European Commission - Planmap
    Keywords: 523 ; chaotic terrains ; hydrothermal system ; mapping ; Mars ; spectral analyses
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  • 4
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    Ultramafic Carbonated Melt‐ and Auto‐Metasomatism in Mantle Eclogites: Compositional Effects and Geophysical Consequences (2021)
    Details
    Publication Date: 2021-07-05
    Description: The mineralogy, chemical composition, and physical properties of cratonic mantle eclogites with oceanic crustal protoliths can be modified by secondary processes involving interaction with fluids and melts, generated in various slab lithologies upon subduction (auto‐metasomatism) or mantle metasomatism after emplacement into the cratonic lithosphere. Here we combine new and published data to isolate these signatures and evaluate their effects on the chemical and physical properties of eclogite. Mantle metasomatism involving kimberlite‐like, ultramafic carbonated melts (UM carbonated melts) is ubiquitous though not pervasive, and affected between ~20% and 40% of the eclogite population at the various localities investigated here, predominantly at ~60–150 km depth, overlapping cratonic midlithospheric seismic discontinuities. Its hallmarks include lower jadeite component in clinopyroxene and grossular component in garnet, an increase in bulk‐rock MgO ± SiO2, and decrease in FeO and Al2O3 contents, and LREE‐enrichment accompanied by higher Sr, Pb, Th, U, and in part Zr and Nb, as well as lower Li, Cu ± Zn. This is mediated by addition of a high‐temperature pyroxene from a UM carbonated melt, followed by redistribution of this component into garnet and clinopyroxene. As clinopyroxene‐garnet trace‐element distribution coefficients increase with decreasing garnet grossular component, clinopyroxene is the main carrier of the metasomatic signatures. UM carbonated melt‐metasomatism at 〉130–150 km has destroyed the diamond inventory at some localities. These mineralogical and chemical changes contribute to low densities, with implications for eclogite gravitational stability, but negligible changes in shear‐wave velocities, and, if accompanied by H2O‐enrichment, will enhance electrical conductivities compared to unenriched eclogites.
    Description: Plain Language Summary: Oceanic crust formed at spreading ridges is recycled in subduction zones and undergoes metamorphism to eclogite. Some of this material is captured in the overlying lithospheric mantle, where it is exhumed by passing magmas. Having formed in spreading ridges, these eclogites have proven invaluable archives for the onset of plate tectonics, for the construction of cratons during subduction/collision, as probes of the convecting mantle from which their precursors formed, and as generators of heterogeneity upon recycling into Earth's convecting mantle. During subduction and until exhumation, interaction with fluids and melts (called metasomatism) can change the mineralogy, chemical composition, and physical properties of mantle eclogites, complicating their interpretation, but a comprehensive study of these effects is lacking so far. We investigated mantle eclogites from ancient continents (cratons) around the globe in order to define hallmarks of metasomatism by subduction‐related fluids and small‐volume ultramafic carbonated mantle melts. We find that the latter is pervasive and occurs predominantly at midlithospheric depths where seismic discontinuities are detected, typically causing diamond destruction and a reduction in density. This has consequences for their gravitational stability and for the interpretation of shearwave velocities in cratons.
    Description: Key Points: Exploration of metasomatic effects during subduction of ancient oceanic crust and after its emplacement into cratonic lithospheric mantle. Metasomatism by kimberlite‐like ultramafic melt affected between 20% and 40% of mantle eclogite suites worldwide, mostly at 2–5 GPa. Metasomatism lowers FeO, hence density in eclogite; no significant effect on shearwave velocities.
    Description: German Research Foundation http://dx.doi.org/10.13039/501100001659
    Description: National Research Foundation (NRF) http://dx.doi.org/10.13039/501100001321
    Description: Wilhelm and Else Heraeus Foundation http://dx.doi.org/10.13039/501100011618
    Description: Deutsche Forschungsgemeinschaft (DFG, INST
    Description: research
    Keywords: 552.4 ; eclogites ; FID-GEO-DE-7
    Language: English
    Type: article , publishedVersion
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  • 5
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    Revisiting global trends in freshwater insect biodiversity (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-06-28
    Description: A recent global meta‐analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns with the meta‐analysis and suggest that these account for the discrepancy with the declines reported elsewhere. First, total abundance and biomass alone are poor indicators of the status of freshwater insect assemblages, and the observed differences may well have been driven by the replacement of sensitive species with tolerant ones. Second, many of the datasets poorly represent global trends and reflect responses to local conditions or nonrandom site selection. We conclude that the results of the meta‐analysis should not be considered indicative of an overall improvement in the condition of freshwater ecosystems. This article is categorized under: Water and Life 〉 Conservation, Management, and Awareness
    Description: Relying on abundance or biomass and examining nonrepresentative datasets limits our ability to infer the condition of freshwater insect communities globally. Photo by Jeremy Monroe, Freshwaters Illustrated: a caddisfly larva from an Oregon Coastal stream, USA (Limnephilidae: Dicosmoecus sp.).
    Description: Federal Agency for Nature Conservation (BfN) http://dx.doi.org/10.13039/100010606
    Description: NSF Macrosystems Biology Program
    Description: Leibniz‐Gemeinschaft http://dx.doi.org/10.13039/501100001664
    Keywords: 577.6 ; freshwater ecosystems ; insect abundance ; long‐term research ; threats
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  • 6
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    Evaluating learning spaces in flood risk management in Germany: Lessons for governance research (2021)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2021-06-28
    Description: Efforts to collaboratively manage the risk of flooding are ultimately based on individuals learning about risks, the decision process, and the effectiveness of decisions made in prior situations. This article argues that much can be learned about a governance setting by explicitly evaluating the relationships through which influential individuals and their immediate contacts receive and send information to one another. We define these individuals as “brokers,” and the networks that emerge from their interactions as “learning spaces.” The aim of this article is to develop strategies to identify and evaluate the properties of a broker's learning space that are indicative of a collaborative flood risk management arrangement. The first part of this article introduces a set of indicators, and presents strategies to employ this list so as to systematically identify brokers, and compare their learning spaces. The second part outlines the lessons from an evaluation that explored cases in two distinct flood risk management settings in Germany. The results show differences in the observed brokers' learning spaces. The contacts and interactions of the broker in Baden‐Württemberg imply a collaborative setting. In contrast, learning space of the broker in North Rhine‐Westphalia lacks the same level of diversity and polycentricity.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: MWK Baden‐Württemberg
    Keywords: 333.91 ; brokerage ; collaborative water governance ; comanagement ; comparative analysis ; social networks
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  • 7
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    Does Export Production Measure Transient Changes of the Biological Carbon Pump's Feedback to the Atmosphere Under Global Warming? (2021)
    Details
    Publication Date: 2021-07-05
    Description: In a widely‐held conception, the biological carbon pump (BCP) is equal to the export of organic matter out of the euphotic zone. Using global ocean‐atmosphere model experiments we show that the change in export production is a poor measure of the biological pump's feedback to the atmosphere. The change in global true oxygen utilization (TOU), an integrative measure of the imprint of the BCP on marine oxygen, however, is in good agreement with the net change in the biogenic air‐sea flux of oxygen. Since TOU correlates very well with apparent oxygen utilization (AOU) in our experiments, we propose to measure the change of AOU from data of global float programs to monitor the feedback of the BCP to the atmosphere. For the current ocean we estimate that BCP changes effect a CO2 uptake by the ocean in the range of 0.07 to 0.14 GtC/yr.
    Description: Plain Language Summary: The biological carbon pump is an important element of marine carbon cycling and climate control on millennium timescales. In a widely‐held conception the export of organic carbon from the productive surface layer of the ocean is used as the essential measure of this carbon pump. Using numerical ocean modeling, we show here that the change in export production is, however, a poor measure of the biological carbon pump's feedback to the atmosphere on centennial timescales. In the contrary, we find that an oxygen‐based measure, the apparent oxygen utilization can be used to quantify the impact of biological pump changes on the atmosphere. Since the apparent oxygen utilization is easily accessible from an existing network of marine floats, our study suggests that the atmospheric impact of any future changes of the biological carbon pump can be monitored and quantified. For past decades our study proposes a negligible CO2 feedback to climate from biological carbon processing.
    Description: Key Points: Apparent oxygen utilization is proposed to quantify the feedback of the biological carbon pump to the atmosphere in a warming ocean. Changes in export production are unrelated to changes in biotic oxygen air‐sea gas exchange. The CO2‐flux due to changes of the biological carbon pump over the recent decades is negligible compared to the total marine CO2 uptake.
    Description: Deutsche Forschungsgemeinschat
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: 551.9 ; biological carbon pump ; export production ; climate change ; AOU
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  • 8
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    Formation and maintenance of subsiding shells around non‐precipitating and precipitating cumulus clouds (2021)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2021-07-20
    Description: A shell of subsiding air is generally known to develop around cumulus clouds and shield them from their environment. We seek here to improve our understanding of such shells by (a) revealing the detailed vertical and horizontal structure of shells surrounding both shallow and deeper clouds, and (b) identifying the mechanisms responsible for in‐shell subsidence generation and maintenance. To that end, a high‐resolution Cloud Resolving Model simulation of the shallow‐to‐deep convection transition over a tropical land surface is analysed with an emphasis on the cloud's near environment. Shells surrounding shallow and deep clouds are found to possess surprisingly similar characteristics. However important differences are observed near cloud top where the deepest clouds are associated with stronger subsidence and broader shells. In the convective outflow region, stronger in‐shell subsidence coincides with strong buoyancy reversal, but also with strong pressure gradients naturally generated by cloud‐top vortex dynamics. A more delicate balance between various processes takes place below, and in‐shell subsidence is only barely sustained as buoyancy reversal is largely compensated by pressure gradients. Finally, while evaporation is clearly the main source of buoyancy reversal everywhere around cloud edges, it is also shown that the downward transport of warmer air from aloft through the subsiding shells may compensate for evaporative cooling to slowly bring in‐shell buoyancy to a near‐neutral state. Overall, while it cannot be denied that evaporative cooling and buoyancy reversal play important roles in generating and sustaining in‐shell subsidence, the present results also emphasise that mechanical forcing at cloud top and downward transport within the shells should not be overlooked.
    Description: Narrow “shells” of subsiding air generally form around cumulus clouds, but the mechanisms responsible for their formation and maintenance are still debated. In this study, the dynamics of these shells is investigated using a high‐resolution simulation of idealized tropical convection. It is shown that in‐shell subsiding motions are generally driven by buoyancy reversal. However, mechanical forcing contributes at least equally at the top of all convective clouds. In addition, it is found that buoyancy reversal due to evaporative cooling may be offset by the downward transport of warmer air from aloft through the subsiding shells.
    Keywords: 551.5 ; cloud dynamics ; near‐cloud environment ; subsiding shells ; tropical convection
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  • 9
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    New insights into lake responses to rapid climate change: the Younger Dryas in Lake Gościąż, central Poland (2021)
    Details
    Publication Date: 2021-05-01
    Description: The sediment profile from Lake Gościąż in central Poland comprises a continuous, seasonally resolved and exceptionally well‐preserved archive of the Younger Dryas (YD) climate variation. This provides a unique opportunity for detailed investigation of lake system responses during periods of rapid climate cooling (YD onset) and warming (YD termination). The new varve record of Lake Gościąż presented here spans 1662 years from the late Allerød (AL) to the early Preboreal (PB). Microscopic varve counting provides an independent chronology with a YD duration of 1149+14/–22 years, which confirms previous results of 1140±40 years. We link stable oxygen isotopes and chironomid‐based air temperature reconstructions with the response of various geochemical and varve microfacies proxies especially focusing on the onset and termination of the YD. Cooling at the YD onset lasted ~180 years, which is about a century longer than the terminal warming that was completed in ~70 years. During the AL/YD transition, environmental proxy data lagged the onset of cooling by ~90 years and revealed an increase of lake productivity and internal lake re‐suspension as well as slightly higher detrital sediment input. In contrast, rapid warming and environmental changes during the YD/PB transition occurred simultaneously. However, initial changes such as declining diatom deposition and detrital input occurred already a few centuries before the rapid warming at the YD/PB transition. These environmental changes likely reflect a gradual increase in summer air temperatures already during the YD. Our data indicate complex and differing environmental responses to the major climate changes related to the YD, which involve different proxy sensitivities and threshold processes.
    Description: National Science Centre
    Description: Virtual Institute of Integrated Climate and Landscape Evolution Analysis (ICLEA)
    Keywords: 551.79 ; central Poland ; Younger Dryas ; sedimentation pattern ; lake sediments
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  • 10
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    Auroral Arcs: The Fracture Theory Revisited (2021)
    Details
    Publication Date: 2021-07-04
    Description: The fracture theory for auroral arcs, developed by the author since 1980, compares the decoupling of the magnetic field from the ionosphere by the auroral acceleration region (AAR) with the breaking of a solid rod. In the latter elastic energy stored by the bending is converted into kinetic energy of the stress release motion. Similarly, magnetic energy stored in sheared magnetic fields is temporarily converted into stress release motions and finally transported as Poynting flux into the AAR. The fracture theory has been especially applied to arcs embedded in the convection of the evening auroral oval. The present study subjects the different steps in the fracture process to a critical analysis in the light of new physical insights. This boils down to a revision of the illustrating cartoon used in the earlier publications, without having affecting the quantitative evaluations. The first revision concerns the height extent of the AAR. It must be largely increased. The second revision introduces a nearly 2‐D magnetohydrodynamics (MHD) turbulence into the state of the AAR. This is supported by high‐altitude electric field data and leads to new view of auroral rays. The third revision describes the transition from the AAR to the ionosphere as structured by so‐called potential fingers, which contain substantial fractions of the total field‐parallel potential drop. The most important modification pertains to the average U‐shaped potential of a spontaneously propagating AAR. While the leading edge of the auroral current sheet is structured by stress release motions, the reverse flow in the rear section escapes simple interpretation. It is proposed that this flow is driven by a turbulent transport of reversed momentum from front to rear in response to the incompressibility of the magnetic field in the acceleration region. This leads to a revision of the field‐aligned currents and wavefield in the rear of the arc.
    Keywords: 538.7 ; auroral current sheet ; embedded auroral arcs ; magnetic stress release ; propagating U‐shaped potentials
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  • 11
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    Sporopollenin chemistry and its durability in the geological record: an integration of extant and fossil chemical data across the seed plants (2021)
    Details
    Publication Date: 2021-07-01
    Description: Sporopollenin is a highly resistant biopolymer that forms the outer wall of pollen and spores (sporomorphs). Recent research into sporopollenin chemistry has opened up a range of new avenues for palynological research, including chemotaxonomic classification of morphologically cryptic taxa. However, there have been limited attempts to directly integrate extant and fossil sporopollenin chemical data. Of particular importance is the impact of sample processing to isolate sporopollenin from fresh sporomorphs, and the extent of chemical changes that occur once sporomorphs enter the geological record. Here, we explore these issues using Fourier transform infrared (FTIR) microspectroscopy data from extant and fossil grass, Nitraria (a steppe plant), and conifer pollen. We show a 98% classification success rate at subfamily level with extant grass pollen, demonstrating a strong taxonomic signature in isolated sporopollenin. However, we also reveal substantial chemical differences between extant and fossil sporopollenin, which can be tied to both early diagenetic changes acting on the sporomorphs and chemical derivates of sample processing. Our results demonstrate that directly integrating extant and late Quaternary chemical data should be tractable as long as comparable sample processing routines are maintained. Consistent differences between extant and deeper time sporomorphs, however, suggests that classifying fossil specimens using extant training sets will be challenging. Further work is therefore required to understand and simulate the effects of diagenetic processes on sporopollenin chemistry.
    Description: Natural Environment Research Council http://dx.doi.org/10.13039/501100000270
    Description: H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Keywords: 560.47 ; sporopollenin ; pollen ; chemotaxonomy ; seed plants ; diagenesis ; Fourier transform infrared (FTIR) microspectroscopy
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  • 12
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    An application of WKBJ theory for triad interactions of internal gravity waves in varying background flows (2021)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2021-07-20
    Description: Motivated by the question of whether and how wave–wave interactions should be implemented into atmospheric gravity‐wave parametrizations, the modulation of triadic gravity‐wave interactions by a slowly varying and vertically sheared mean flow is considered for a non‐rotating Boussinesq fluid with constant stratification. An analysis using a multiple‐scale WKBJ (Wentzel–Kramers–Brillouin–Jeffreys) expansion identifies two distinct scaling regimes, a linear off‐resonance regime, and a nonlinear near‐resonance regime. Simplifying the near‐resonance interaction equations allows for the construction of a parametrization for the triadic energy exchange which has been implemented into a one‐dimensional WKBJ ray‐tracing code. Theory and numerical implementation are validated for test cases where two wave trains generate a third wave train while spectrally passing through resonance. In various settings, of interacting vertical wavenumbers, mean‐flow shear, and initial wave amplitudes, the WKBJ simulations are generally in good agreement with wave‐resolving simulations. Both stronger mean‐flow shear and smaller wave amplitudes suppress the energy exchange among a resonantly interacting triad. Experiments with mean‐flow shear as strong as in the vicinity of atmospheric jets suggest that internal gravity‐wave dynamics are dominated in such regions by wave modulation. However, triadic gravity‐wave interactions are likely to be relevant in weakly sheared regions of the atmosphere.
    Description: This study explores wave–wave interactions of modulated internal gravity waves (GWs) in varying background flows using WKBJ techniques. The resulting ray‐tracing model (b) is compared to wave‐resolving LES (a). As a key result, we find that wave modulation partially suppresses the energy exchange in triadic GW interactions, and thus triadic GW interactions are likely to be relevant in weakly sheared regions of the atmosphere.
    Description: German Research Foundation (DFG) US National Science Foundation
    Keywords: 551.5 ; internal gravity waves ; parametrization ; ray‐tracing ; triadic wave–wave interaction ; wave modulation
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  • 13
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    The Boulder Population of Asteroid 4 Vesta: Size‐Frequency Distribution and Survival Time (2021)
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    Publication Date: 2021-07-04
    Description: Dawn's framing camera observed boulders on the surface of Vesta when the spacecraftwas in its lowest orbit (Low Altitude Mapping Orbit, LAMO). We identified, measured, and mapped boulders in LAMO images, which have a scale of 20 m per pixel. We estimate that our sample is virtually complete down to a boulder size of 4 pixels (80 m). The largest boulder is a 400 m‐sized block on the Marcia crater floor. Relatively few boulders reside in a large area of relatively low albedo, surmised to be the carbon‐rich ejecta of the Veneneia basin, either because boulders form less easily here or live shorter. By comparing the density of boulders around craters with a known age, we find that the maximum boulder lifetime is about 300 Ma. The boulder size‐frequency distribution (SFD) is generally assumed to follow a power law. We fit power laws to the Vesta SFD by means of the maximum likelihood method, but they do not fit well. Our analysis of power law exponents for boulders on other small Solar System bodies suggests that the derived exponent is primarily a function of boulder size range. The Weibull distribution mimics this behavior and fits the Vesta boulder SFD well. The Weibull distribution is often encountered in rock grinding experiments and may result from the fractal nature of cracks propagating in the rock interior. We propose that, in general, the SFD of particles (including boulders) on the surface of small bodies follows a Weibull distribution rather than a power law.
    Description: Key Points: We mapped boulders larger than 60 m on asteroid Vesta and found all associated with impact craters. The maximum lifetime of these large Vesta boulders is about 300 Ma, similar to that of meter‐sized lunar boulders. Their cumulative size‐frequency distribution is best fit by a Weibull distribution rather than a power law.
    Keywords: 523 ; Vesta ; Asteroid
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  • 14
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    Facilitated crystal handling using a simple device for evaporation reduction in microtiter plates (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-03-30
    Description: In the past two decades, most of the steps in a macromolecular crystallography experiment have undergone tremendous development with respect to speed, feasibility and increase of throughput. The part of the experimental workflow that is still a bottleneck, despite significant efforts, involves the manipulation and harvesting of the crystals for the diffraction experiment. Here, a novel low‐cost device is presented that functions as a cover for 96‐well crystallization plates. This device enables access to the individual experiments one at a time by its movable parts, while minimizing evaporation of all other experiments of the plate. In initial tests, drops of many typically used crystallization cocktails could be successfully protected for up to 6 h. Therefore, the manipulation and harvesting of crystals is straightforward for the experimenter, enabling significantly higher throughput. This is useful for many macromolecular crystallography experiments, especially multi‐crystal screening campaigns.
    Description: A simple and low‐cost device has been developed to minimize evaporation in microtiter plates for easy crystal handling and harvesting. image
    Keywords: 548 ; evaporation reduction ; crystal handling ; crystal harvesting ; crystallographic fragment screening
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    Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability (2021)
    Details
    Publication Date: 2021-07-04
    Description: Geological evidence indicates large continental‐scale Antarctic ice volume variations during the early and mid‐Miocene. On million‐year timescales, these variations can largely be explained by equilibrium Antarctic ice sheet (AIS) simulations. In contrast, on shorter orbital timescales, the AIS needs not be in equilibrium with the forcing and ice volume variations may be substantially different. Here, we introduce a conceptual model, based on ice dynamical model results, to investigate the difference between transient variability and equilibrium differences of the Miocene AIS. In our model, an ice sheet will grow (shrink) by a specific rate when it is smaller (larger) than its equilibrium size. We show that phases of concurrent ice volume increase and rising CO2 levels are possible, even though the equilibrium ice volume decreases monotonically with CO2. When the AIS volume is out of equilibrium with the forcing climate, the ice sheet can still be adapting to a relatively large equilibrium size, although CO2 is rising after a phase of decrease. A delayed response of Antarctic ice volume to (covarying) solar insolation and CO2 concentrations can cause discrepancies between Miocene solar insolation and benthic δ18O variability. Increasing forcing frequency leads to a larger disequilibrium and consequently larger CO2‐ice volume phase differences. Furthermore, an amplified forcing amplitude causes larger amplitude ice volume variability, because the growth and decay rates depend on the forcing. It also leads to a reduced average ice volume, resulting from the growth rates generally being smaller than the decay rates.
    Description: Plain Language Summary: The early and mid‐Miocene (23–14 Myr ago) was the last period in Earth's history when the Antarctic ice sheet (AIS) size changed between being almost completely vanished and its current magnitude. So far, ice modelers have tried explaining this large‐scale AIS variability using steady‐state experiments, in which the final ice volume is in equilibrium with the forcing climate. In these simulations, phases of simultaneous ice sheet growth and CO2 increase have to be caused by increased precipitation outweighing increased melt in a warmer climate. Conversely, simultaneous ice sheet decay and CO2 decrease must be due to decreased precipitation exceeding decreased melt. Here, we provide an alternative explanation for these phases, based on the notion that the slowly evolving AIS is not in equilibrium with the forcing climate. In our model, an ice sheet will grow (shrink) by a specific rate when it is smaller (larger) than its equilibrium size. The AIS can then still be adapting to a relatively large equilibrium size, when CO2 is already increasing again after an initial drop. It can also continue decaying after a reversal from rising to sinking CO2 levels. Our results serve to aid the interpretation of Miocene geological oxygen isotope data.
    Description: Key Points: Concurrent Antarctic ice sheet growth and CO2 level rise can occur because of disequilibrium between ice volume and climate. The disequilibrium and CO2‐ice volume phase differences grow with increasing frequency of the forcing. Larger amplitude CO2 variability causes larger amplitude ice volume variability and a smaller average ice sheet.
    Keywords: 551 ; Miocene ; Antarctica ; ice sheet ; sea level ; carbon dioxide
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    Quartz and cristobalite ballen in impact melt rocks from the Ries impact structure, Germany, formed by dehydration of shock‐generated amorphous phases (2021)
    Details
    Publication Date: 2021-07-05
    Description: Quartz and cristobalite ballen aggregates surrounded by dendritic cristobalite in gneiss clasts of impact melt rocks from the Ries impact structure are analyzed by Raman spectroscopy, microscopy, and electron backscattered diffraction to elucidate the development of the characteristic polycrystalline ballen that are defined by curved interfaces between each other. We suggest that the investigated ballen aggregates represent former fluid inclusion‐rich quartz grains from the granitic gneiss protolith. Upon shock loading, they transformed into an amorphous phase that partly retained information on the precursor structure. Volatiles from inclusions dissolved into the amorphous phase. During decompression and cooling, dehydration takes place and causes fracturing of the amorphous phase and disintegration into small globular ballen, with the fluid being expelled along the fractures. A similar formation of small globules due to dehydration of silica‐rich glass is known for perlitic structures of volcanic rocks. Remnants of the precursor structure are present in the amorphous phase and enabled topotactic crystallization of quartz, leading to a crystallographic preferred orientation. Crystallization of more distorted parts of the amorphous phase led to random orientations of the quartz crystals. Ballen comprised of cristobalite formed from a dehydrated amorphous phase with no structural memory of the precursor. Dendritic cristobalite exclusively occurring at the rim of quartz ballen aggregate is interpreted to have crystallized directly from a melt enriched in fluids that were expelled during dehydration of the amorphous phase.
    Description: SNSB-Innovativ Projekt Ballenquarz
    Keywords: 549
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    Variscan ultra‐high‐pressure eclogite in the Upper Allochthon of the Rhodope Metamorphic Complex (Bulgaria) (2021)
    Details
    Publication Date: 2021-07-05
    Description: The Rhodope Metamorphic Complex (RMC) in Bulgaria has been established as a Mesozoic ultra‐high‐pressure metamorphic province by findings of microdiamond in gneisses. Additionally, Variscan ultra‐high‐pressure metamorphism has been proposed for the Ograzhden/Vertiskos Unit in the Upper Allochthon of the RMC, based on findings of coesite, graphite pseudomorphs after diamond and indirect age constraints. We confirm ultra‐high‐pressure metamorphism of eclogites in this unit using thermobarometry, phase‐equilibrium modelling and the Variscan age of metamorphism using Lu–Hf garnet–whole‐rock dating. In Belica (southern Rila Mountains), kyanite‐ and phengite‐bearing eclogite enclosed in high‐grade gneisses records P‐T conditions of 3.0–3.5 GPa and 700–750°C. Lu–Hf dating of eclogite samples from Belica and Gega (Ograzhden Mountain), where coesite was found, yielded ages of 334.1 ± 1.8 and 334.0 ± 2.2 Ma, respectively, interpreted as the age of garnet growth during post‐collisional subduction of continental crust after closure of the Rheic Ocean.
    Description: Slovak Research and Development Agency http://dx.doi.org/10.13039/501100005357
    Description: University of Bonn
    Description: VEGA http://dx.doi.org/10.13039/501100006109
    Keywords: 552.4 ; Rhodope Metamorphic Complex ; eclogite
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  • 18
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    Quartzite procurement in conglomerates and deposits: Geoarchaeological characterization of potential catchment areas in the central part of the Cantabrian Region, Spain (2021)
    Details
    Publication Date: 2021-07-20
    Description: Raw material characterization in Paleolithic archaeology has widened our knowledge of Middle Paleolithic societies. Procurement of raw material, specifically flint, has allowed the tracing of the mobility of both stones and people, as well as selective processes to obtain specific types or even extraction activities. The analysis of quartzite has also developed in recent years, providing an opportunity to better understand prehistoric societies. This study characterizes the procurement strategies implemented by Middle Paleolithic people in the mountainous region of the Picos de Europa. To this end, we present a comprehensive characterization of potential catchment areas: massive outcrops, conglomerates, and river deposits. The exploitation of quartzite at the sites of El Habario and El Arteu allows us to understand the territorial management of this mountainous area through the combination of selective processes and mobility mechanisms in lower and middle altitudes. These perspectives enable us to view the mountainous region not as a barrier but as an environmental mosaic managed by Middle Paleolithic groups. This study shows strategies that bring together direct and embedded procurement based on both intensive and extensive searches. These discourses are more closely related to the daily life of people than those only considering the mobility of people and objects.
    Description: A comprehensive geoarchaeological research project based on the integration of a geographic information system, field survey, stereomicroscopy, and thin‐section petrography, is presented to characterize potential procurement areas of quartzite. The application of this methodology in the Deva, Cares, and Güeña valleys and in three different geological contexts; massive outcrops, conglomerates, and secondary deposits, suggest potential acquisition processes of lithic resources. The analysis of the quartzite assemblages of El Habario and El Arteu unveils complex management of terrain based on a mobility mechanism that connects middle altitude plateaus with open and lower river valleys, as well as intensive and extensive procurement mechanisms of raw material.
    Description: Education Department of the Government of the Basque Country
    Description: The Spanish Ministry of Science Project
    Description: The Consolidated Research Group in Prehistory of the Basque Country University
    Keywords: 552.4 ; Cantabrian Region ; field survey ; Middle Paleolithic ; petrology ; quartzite ; raw material procurement
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    Extreme precipitation events in the Mediterranean: Spatiotemporal characteristics and connection to large‐scale atmospheric flow patterns (2021)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2021-07-01
    Description: The Mediterranean region is strongly affected by extreme precipitation events (EPEs), sometimes leading to severe negative impacts on society, economy, and the environment. Understanding such natural hazards and their drivers is essential to mitigate related risks. Here, EPEs over the Mediterranean between 1979 and 2019 are analysed, using ERA5, the latest reanalysis dataset from ECMWF. EPEs are determined based on the 99th percentile of their daily distribution (P99). The different EPE characteristics are assessed, based on seasonality and spatiotemporal dependencies. To better understand their connection to large‐scale atmospheric flow patterns, Empirical Orthogonal Function analysis and subsequent non‐hierarchical K‐means clustering are used to quantify the importance of weather regimes to EPE frequency. The analysis is performed for different variables, depicting atmospheric variability in the lower and middle troposphere. Results show a clear spatial division in EPE occurrence, with winter and autumn being the seasons of highest EPE frequency for the eastern and western Mediterranean, respectively. There is a high degree of temporal dependencies with 20% of the EPEs (median value based on all studied grid cells), occurring up to 1 week after a preceding P99 event at the same location. Local orography is a key modulator of the spatiotemporal connections and substantially enhances the probability of co‐occurrence of EPEs even for distant locations. The clustering clearly demonstrates the prevalence of distinct synoptic‐scale atmospheric conditions during the occurrence of EPEs for different locations within the region. Results indicate that clustering, based on a combination of sea level pressure (SLP) and geopotential height at 500 hPa (Z500), can increase the conditional probability of EPEs by more than three (3) times (median value for all grid cells) from the nominal probability of 1% for the P99 EPEs. Such strong spatiotemporal dependencies and connections to large‐scale patterns can support extended‐range forecasts.
    Description: This study analyses the spatiotemporal characteristics of extreme precipitation events over the Mediterranean, and their connection to large‐scale atmospheric flow patterns. It is shown that by conditioning the extremes based on the atmospheric variability in the low‐ and mid‐troposphere, their probability increases more than threefold, when using nine clusters to group all the synoptic daily patterns. This finding can support extended‐range forecasts, as for such lead times the NWP models are more skillful in predicting large‐scale patterns than localized extremes.
    Description: Marie Skłodowska‐Curie
    Description: European Union's Horizon 2020
    Keywords: 551.6 ; extreme precipitation ; large‐scale/circulation patterns ; Mediterranean ; weather regimes
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    Water temperature control on CO2 flux and evaporation over a subtropical seagrass meadow revealed by atmospheric eddy covariance (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-07-01
    Description: Subtropical seagrass meadows play a major role in the coastal carbon cycle, but the nature of air–water CO2 exchanges over these ecosystems is still poorly understood. The complex physical forcing of air–water exchange in coastal waters challenges our ability to quantify bulk exchanges of CO2 and water (evaporation), emphasizing the need for direct measurements. We describe the first direct measurements of evaporation and CO2 flux over a calcifying seagrass meadow near Bob Allen Keys, Florida. Over the 78‐d study, CO2 emissions were 36% greater during the day than at night, and the site was a net CO2 source to the atmosphere of 0.27 ± 0.17 μmol m−2 s−1 (x̅ ± standard deviation). A quarter (23%) of the diurnal variability in CO2 flux was caused by the effect of changing water temperature on gas solubility. Furthermore, evaporation rates were ~ 10 times greater than precipitation, causing a 14% increase in salinity, a potential precursor of seagrass die‐offs. Evaporation rates were not correlated with solar radiation, but instead with air–water temperature gradient and wind shear. We also confirm the role of convective forcing on night‐time enhancement and day‐time suppression of gas transfer. At this site, temperature trends are regulated by solar heating, combined with shallow water depth and relatively consistent air temperature. Our findings indicate that evaporation and air–water CO2 exchange over shallow, tropical, and subtropical seagrass ecosystems may be fundamentally different than in submerged vegetated environments elsewhere, in part due to the complex physical forcing of coastal air–sea gas transfer.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Keywords: 551.5 ; Florida ; Bob Allen Keys ; seagrass meadows ; air–water CO2 exchanges ; biometeorological measurements
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    Disentangling the Impact of Catchment Heterogeneity on Nitrate Export Dynamics From Event to Long‐Term Time Scales (2021)
    Details
    Publication Date: 2021-07-05
    Description: Defining effective measures to reduce nitrate pollution in heterogeneous mesoscale catchments remains challenging when based on concentration measurements at the outlet only. One reason for this is our limited understanding of the subcatchment contributions to nitrate export and their importance at different time scales. While upstream subcatchments often disproportionally contribute to runoff generation and in turn to nutrient export, agricultural areas (which are typically found in downstream lowlands) are known to be a major source of nitrate pollution. To examine the interplay of different subcatchments, we analyzed seasonal long‐term trends and event dynamics of nitrate concentrations, loads, and the concentration–discharge relationship in three nested catchments within the Selke catchment (456 km2), Germany. The upstream subcatchments (40.4% of total catchment area, 34.5% of N input) had short transit times and dynamic concentration–discharge relationships with elevated nitrate concentrations during wet seasons and events. Consequently, the upstream subcatchments dominated nitrate export during high flow and disproportionally contributed to overall annual nitrate loads at the outlet (64.2%). The downstream subcatchment was characterized by higher N input, longer transit times, and relatively constant nitrate concentrations between seasons, dominating nitrate export during low‐flow periods. Neglecting the disproportional role of upstream subcatchments for temporally elevated nitrate concentrations and net annual loads can lead to an overestimation of the role of agricultural lowlands. Nonetheless, constantly high concentrations from nitrate legacies pose a long‐term threat to water quality in agricultural lowlands. This knowledge is crucial for an effective and site‐specific water quality management.
    Description: Plain Language Summary: To efficiently remove nitrate pollution, we need to understand how it is transported, mobilized, and stored within large and heterogeneous catchments. Previous studies have shown that upstream catchments often have a disproportional impact on nutrient export, while agriculture (a major nitrate source) is often located in downstream lowlands. To understand which parts of a catchment contribute most to nitrate export and when, we analyzed long‐term (1983–2016) and high‐frequency (2010–2016) data in the Selke catchment (Germany) at three locations. The mountainous upstream part dominated nitrate transport during winter, spring, and rain events. It had a surprisingly high contribution to annual nitrate loads. The agricultural downstream part of the catchment dominated nitrate export during summer and autumn, with relatively constant concentrations between seasons. Here, nitrogen inputs needed more than a decade to travel through the subsurface of the catchment, which causes a time lag between measures to reduce nitrate pollution and their measurable effect. The resulting storage of nitrate in the groundwater threatens drinking water quality for decades to come. While the role of agricultural lowlands for nitrate export can be overestimated if neglecting the disproportional role of upstream subcatchments, their impact poses a long‐term threat to water quality.
    Description: Key Points: Analyzing the CQ relationship across time scales allows the disentanglement of the impact of catchment heterogeneity on nitrate export. Mountainous upstream subcatchments can dominate nitrate export during high flows and disproportionally contribute to nitrate loads. Agricultural downstream subcatchments can dominate nitrate export during low flow and pose a long‐term threat to water quality.
    Description: DFG collaborative research center (SFB) 1253 “CAMPOS”
    Description: Helmholtz Research Program, Integrated Project “Water and Matter Flux Dynamics in Catchments”
    Description: Initiative and Networking Fund of the Helmholtz Association through the project Advanced Earth System Modelling Capacity (ESM)
    Keywords: 551 ; concentration–discharge relationships ; event dynamics ; long‐term trends ; nitrate ; nutrient export ; water quality
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    Cation distribution in Cu2ZnSnSe4, Cu2FeSnS4 and Cu2ZnSiSe4 by multiple‐edge anomalous diffraction (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-03-30
    Description: Multiple‐Edge Anomalous Diffraction (MEAD) has been applied to various quaternary sulfosalts belonging to the adamantine compound family in order to validate the distribution of copper, zinc and iron cations in the structure. Semiconductors from this group of materials are promising candidates for photovoltaic applications. Their properties strongly depend on point defects, in particular related to cation order–disorder. However, Cu+, Zn2+ and Fe2+ have very similar scattering factors and are all but indistinguishable in usual X‐ray diffraction experiments. Anomalous diffraction utilizes the dependency of the atomic scattering factors f′ and f′′ of the energy of the radiation, especially close to the element‐specific absorption edges. In the MEAD technique, individual Bragg peaks are tracked over an absorption edge. The intensity changes depending on the structure factor can be highly characteristic for Miller indices selected for a specific structural problem, but require very exact measurements. Beamline KMC‐2 at synchrotron BESSY II, Berlin, has been recently upgraded for this technique. Anomalous X‐ray powder diffraction and XAFS compliment the data. Application of this technique confirmed established cation distribution in Cu2ZnSnSe4 (CZTSe) and Cu2FeSnS4 (CFTS). In contrast to the literature, cation distribution in Cu2ZnSiSe4 (CZSiSe) is shown to adopt a highly ordered wurtz‐kesterite structure type.
    Description: Multiple‐Edge Anomalous Diffraction (MEAD) has been applied to various quaternary sulfosalts belonging to the adamantine compound family in order to validate the distribution of copper, zinc and iron cations in the structure. Application of this technique confirms established cation distribution in Cu2ZnSnSe4 (CZTSe) and Cu2FeSnS4 (CFTS), but in Cu2ZnSiSe4 (CZSiSe) the cation distribution is shown to adopt a highly ordered wurtz‐kesterite structure type in contrast to the literature. image
    Keywords: 548 ; synchrotron ; anomalous diffraction ; semiconductor ; MEAD
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    Ethical consumerism: Veganism (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-06-28
    Description: In this article, we review an array of positions in the contemporary literature that concern the moral reasons for vegan consumerism. We situate veganism within the broader field of ethical consumerism, present a variety of motivations and justifications for veganism, and discuss criticisms of vegan consumerism. The arguments presented in the article ultimately pertain to the question of whether concerns for animals, human rights, or climate justice entail strong moral reasons to adopt a vegan lifestyle. Additionally, we address issues of particular relevance for political philosophy, such as whether organized vegan consumer campaigns are a politically legitimate means to strive for structural change. We hope to show that there are anthropocentric, as well as animal‐centered, reasons that speak in favor of radically reformed human–animal relations, including diets that are at least predominantly plant‐based. This article is categorized under: Climate, Nature, and Ethics 〉 Ethics and Climate Change
    Description: Alexander von Humboldt‐Stiftung (Feodor Lynen Research Scholarship) http://dx.doi.org/10.13039/100005156
    Keywords: 304.2 ; animal ethics ; climate ethics ; climate justice ; ethical consumption ; veganism
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    Impact of an 0.2 km3 Rock Avalanche on Lake Eibsee (Bavarian Alps, Germany) – Part II: Catchment Response to Consecutive Debris Avalanche and Debris Flow (2021)
    Details
    Publication Date: 2021-07-01
    Description: The ~0.2 km3 Eibsee rock avalanche impacted Paleolake Eibsee and completely displaced its waters. This study analyses the lake impact and the consequences, and the catchment response to the landslide. A quasi‐3D seismic reflection survey, four sediment cores from modern Lake Eibsee, reaching far down into the rock avalanche mass, nine radiocarbon ages, and geomorphic analysis allow us to distinguish the main rock avalanche event from a secondary debris avalanche and debris flow. The highly fluidized debris avalanche formed a megaturbidite and multiple swashes that are recorded in the lake sediments. The new calibrated age for the Eibsee rock avalanche of ~4080–3970 cal yr BP indicates a coincidence with rockslides in the Fernpass cluster and subaquatic landslides in Lake Piburg and Lake Plansee, and raises the possibility that a large regional earthquake triggered these events. We document a complex history of erosion and sedimentation in Lake Eibsee, and demonstrate how the catchment response and rebirth of the lake are revealed through the complementary application of geophysics, sedimentology, radiocarbon dating, and geomorphology. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Description: Sedimentological, geophysical and geomorphological investigation in and around Lake Eibsee allows to decipher three rock‐slope failures from Mount Zugspitze: (i) the Eibsee rock avalanche ~4000 cal yr BP; (ii) a debris avalanche in the aftermath; and (iii) a large debris flow ~3740 cal yr BP. The Eibsee rock avalanche was re‐dated to a refined age of 4089–3876 cal yr BP. The coincidence with major events in the Fernpass rockslide cluster increases the likelihood of a prehistoric earthquake trigger.
    Description: Studienstiftung des Deutschen Volkes e.V. (German National Academic Foundation): http://dx.doi.org/10.13039/501100004350
    Description: British Society for Geomorphology http://dx.doi.org/10.13039/100010165
    Keywords: 551 ; rock avalanche ; lake impact ; lake sediments ; catchment response ; progressive slope failure ; recurrence rates ; prehistoric earthquake ; Fernpass rockslide cluster
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    Strain migration during multiphase extension, Stord Basin, northern North Sea rift (2021)
    Details
    Publication Date: 2021-07-01
    Description: In regions experiencing multiple phases of extension, rift‐related strain can vary along and across the basin during and between each phase, and the location of maximum extension can differ between the rift phase. Despite having a general understanding of multiphase rift kinematics, it remains unclear why the rift axis migrates between extension episodes. The role pre‐existing structures play in influencing fault and basin geometries during later rifting events is also poorly understood. We study the Stord Basin, northern North Sea, a location characterised by strain migration between two rift episodes. To reveal and quantify the rift kinematics, we interpreted a dense grid of 2D seismic reflection profiles, produced time‐structure and isochore (thickness) maps, collected quantitative fault kinematic data and calculated the amount of extension (β‐factor). Our results show that the locations of basin‐bounding fault systems were controlled by pre‐existing crustal‐scale shear zones. Within the basin, Permo‐Triassic Rift Phase 1 (RP1) faults mainly developed orthogonal to the E‐W extension direction. Rift faults control the locus of syn‐RP1 deposition, whilst during the inter‐rift stage, areas of clastic wedge progradation are more important in controlling sediment thickness trends. The calculated amount of RP1 extension (β‐factor) for the Stord Basin is up to β = 1.55 (±10%, 55% extension). During the subsequent Middle Jurassic‐Early Cretaceous Rift Phase 2 (RP2), however, strain localised to the west along the present axis of the South Viking Graben, with the Stord Basin being almost completely abandoned. Rift axis migration during RP2 is interpreted to be related to changes in lithospheric strength profile, possibly related to the ultraslow extension (〈1 mm/year during RP1), the long period of tectonic quiescence (ca. 50 myr) between RP1 and RP2 and possible underplating. Our results highlight the very heterogeneous nature of temporal and lateral strain migration during and between extension phases within a single rift basin.
    Description: Norges Forskningsråd http://dx.doi.org/10.13039/501100005416
    Keywords: 551.8 ; crustal extension ; multirifted basin ; Northern North Sea ; seismic interpretation ; tectonics and sedimentation
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    The copper(II)‐binding tripeptide GHK, a valuable crystallization and phasing tag for macromolecular crystallography (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-03-27
    Description: The growth of diffraction‐quality crystals and experimental phasing remain two of the main bottlenecks in protein crystallography. Here, the high‐affinity copper(II)‐binding tripeptide GHK was fused to the N‐terminus of a GFP variant and an MBP‐FG peptide fusion. The GHK tag promoted crystallization, with various residues (His, Asp, His/Pro) from symmetry molecules completing the copper(II) square‐pyramidal coordination sphere. Rapid structure determination by copper SAD phasing could be achieved, even at a very low Bijvoet ratio or after significant radiation damage. When collecting highly redundant data at a wavelength close to the copper absorption edge, residual S‐atom positions could also be located in log‐likelihood‐gradient maps and used to improve the phases. The GHK copper SAD method provides a convenient way of both crystallizing and phasing macromolecular structures, and will complement the current trend towards native sulfur SAD and MR‐SAD phasing.
    Description: A novel three‐residue tag containing the residues GHK that can be used to promote crystallization and in SAD phasing experiments using its tightly bound copper ion is described. image
    Keywords: 548 ; phasing ; crystallization ; GHK ; SAD
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    Sustainable Cathodes for Lithium‐Ion Energy Storage Devices Based on Tannic Acid—Toward Ecofriendly Energy Storage (2021)
    Details
    Publication Date: 2021-07-01
    Description: The use of organic materials with reversible redox activity holds enormous potential for next‐generation Li‐ion energy storage devices. Yet, most candidates are not truly sustainable, i.e., not derived from renewable feedstock or made in benign reactions. Here an attempt is reported to resolve this issue by synthesizing an organic cathode material from tannic acid and microporous carbon derived from biomass. All constituents, including the redox‐active material and conductive carbon additive, are made from renewable resources. Using a simple, sustainable fabrication method, a hybrid material is formed. The low cost and ecofriendly material shows outstanding performance with a capacity of 108 mAh g−1 at 0.1 A g−1 and low capacity fading, retaining approximately 80% of the maximum capacity after 90 cycles. With approximately 3.4 V versus Li+/Li, the cells also feature one of the highest reversible redox potentials reported for biomolecular cathodes. Finally, the quinone‐catecholate redox mechanism responsible for the high capacity of tannic acid is confirmed by electrochemical characterization of a model compound similar to tannic acid but without catecholic groups.
    Description: Tannic acid and sucrose‐derived porous carbon are combined to create a hybrid material using ball milling. The sustainable hybrid material shows exceptional properties as a cathode material for lithium‐ion energy storage devices that combines energy storage using both a redox process, from tannic acid, and electric double‐layer capacitance, from the porous carbon.
    Description: DFG http://dx.doi.org/10.13039/100004807
    Description: German Federal Ministry of Education and Research
    Description: BMBF http://dx.doi.org/10.13039/501100002347
    Description: Fraunhofer‐Max Planck cooperation project
    Description: Max Planck Society http://dx.doi.org/10.13039/501100004189
    Description: Max Planck Institute of Colloids and Interfaces
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: 333.79 ; biomass ; electrochemistry ; energy storage ; redox chemistry ; sustainability ; tannic acid
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    A chronological and palaeoenvironmental re‐evaluation of two loess‐palaeosol records in the northern Harz foreland, Germany, based on innovative modelling tools (2021)
    Details
    Publication Date: 2021-04-14
    Description: The continuing development of analytical methods for investigating sedimentary records calls for iterative re‐examination of existing data sets obtained on loess‐palaeosol sequences (LPS) as archives of palaeoenvironmental change. Here, we re‐investigate two LPS (Hecklingen, Zilly) in the northern Harz foreland, Germany, being of interest due to their proximity to the Scandinavian Ice Sheet (SIS) and the position between oceanic climatic influence further west and continental influence towards the east. First, we established new quartz OSL and polymineral IRSL chronologies. Both methods show concordant ages in the upper part of the Hecklingen profile (~20–40 ka), but in the lower part IRSL underestimates OSL ages by up to ~15 ka for the period 40–60 ka. Interpretations hence refer to the OSL data set. Second, we applied Bayesian age‐depth modelling to data sets from Hecklingen to resolve inversions in the original ages, also reducing averaged 1σ uncertainty by ~19% (OSL) and ~12% (IRSL). Modelled chronologies point out phases of increased (MIS 2, early MIS 3) and reduced (middle and late MIS 3) sedimentation, but interpretation of numerical rates is problematic because of intense erosion and slope wash particularly during MIS 3. Finally, previously obtained grain‐size data were re‐investigated by end member modelling analyses. Three fundamental grain‐size distributions (loadings) explain the measured data sets and offer information on intensity and – combined with modelled OSL ages – timing of geomorphic processes. We interpret the loadings to represent (i) primary loess accumulation, (ii) postdepositional pedogenesis and/or input of aeolian fine fractions, and (iii) input of coarse aeolian material and/or slope wash. The applied modelling tools facilitate detailed understanding of site‐formation through time, allowing us to correlate a strong peak in mean grain size at ~26–24 ka to the maximum extent of the SIS and increased influence of easterly winds.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: 551 ; Harz foreland ; loess-palaeosol sequences ; luminescence ages ; Bayesian age-depth modelling ; sedimentation rates
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    Detectability of Artificial Ocean Alkalinization and Stratospheric Aerosol Injection in MPI‐ESM (2021)
    Details
    Publication Date: 2021-07-05
    Description: To monitor the success of carbon dioxide removal (CDR) or solar radiation management (SRM) that offset anthropogenic climate change, the forced response to any external forcing is required to be detectable against internal variability. Thus far, only the detectability of SRM has been examined using both a stationary and nonstationary detection and attribution method. Here, the spatiotemporal detectability of the forced response to artificial ocean alkalinization (AOA) and stratospheric aerosol injection (SAI) as exemplary methods for CDR and SRM, respectively, is compared in Max Planck Institute Earth System Model (MPI‐ESM) experiments using regularized optimal fingerprinting and single‐model estimates of internal variability, while working under a stationary or nonstationary null hypothesis. Although both experiments are forced by emissions according to the Representative Concentration Pathway 8.5 (RCP8.5) and target the climate of the RCP4.5 scenario using AOA or SAI, detection timescales reflect the fundamentally different forcing agents. Moreover, detectability timescales are sensitive to the choice of null hypothesis. Globally, changes in the CO2 system in seawater are detected earlier than the response in temperature to AOA but later in the case of SAI. Locally, the detection time scales depend on the physical, chemical, and radiative impacts of CDR and SRM forcing on the climate system, as well as patterns of internal variability, which is highlighted for oceanic heat and carbon storage.
    Description: Key Points: Detectability is robust using regularized optimal fingerprinting and single‐model estimates of internal variability. Changes in the CO2 system in seawater are detected earlier than the thermodynamic response to AOA but later in the case of SAI. Local detectability depends on patterns of internal variability and physical, chemical, and radiative impacts of external forcing.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: Open access funding enabled and organized by Projekt DEAL.
    Keywords: 551.9 ; detection and attribution ; ocean alkalinization ; stratospheric aerosol injection ; Earth system modeling
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    Direct‐Push Color Logging Images Spatial Heterogeneity of Organic Carbon in Floodplain Sediments (2021)
    Details
    Publication Date: 2021-07-05
    Description: In soils and sediments, large amounts of total organic carbon (TOC) mark reducing conditions. As dark sediment colors are good predictors for high‐TOC zones, they indicate hot spots of biogeochemical turnover and microbial activity. Traditionally, obtaining the sediment color or TOC at depth requires costly core sampling, resulting in poor horizontal resolution and related uncertainty caused by interpolation. We suggest using a direct‐push tool for optical screening of the sediment color to acquire multiple high‐resolution vertical color profiles and demonstrate its applicability to a biogeochemical transition zone in floodplain sediments, dominated by tufa. We use Gaussian mixture models for a cluster analysis of 35 color logs in the International Commission on Illumination (CIE) L*a*b* color space to identify three colorfacies that differ in lithology and TOC content: a dark colorfacies that agrees well with peat layers, a gray colorfacies associated with clay, and a creamy‐brown facies made of autochthonous carbonate precipitates. We test different approaches either to infer the TOC content from color metrics, namely, the lightness and chroma, across all facies, or to identify TOC ranges for each colorfacies. Given the high variability in TOC due to organic carbon specks in the tufa, the latter approach appears more realistic. In our application we map the 3‐D distribution of organic matter in a floodplain in distinct facies over 20,000 m2 down to 12 m depth. While we relate the sediment color only to the TOC content, direct‐push color logging may also be used for in situ mapping of other biogeochemically relevant properties, such as the ferric‐iron content or sedimentary structure.
    Description: Plain Language Summary: Geologists can say a lot about soils and loose materials in the ground by looking at their color. Dark materials normally contain dead plants, called organic carbon, which are food for bacteria and cause chemical reactions. To get the color of the soil, geologists normally need soil samples, but getting them from depth takes time and money. We test a method of pushing a camera into the ground and recording the color therein. From the recorded color we can say which type of geological material is at which depth and how much organic carbon is there without taking samples everywhere. This can be done very quickly, so that we can do it over a large area and down to the depth of the loose material in the ground, where most of the groundwater flows.
    Description: Key Points: Direct‐push methods allow vertical in situ profiling of sediment color at high resolution. Cluster analysis reproducibly delineates colorfacies indicative of sedimentary units. Site‐specific relationships between color and TOC in sediments permit identifying biogeochemical hot spots.
    Description: German Research Foundation (Deutsche Forschungsgemeinschaft, DFG)
    Keywords: 551.9 ; direct‐push ; color logging ; colorfacies ; peat ; total organic carbon (TOC)
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    Determining paracrystallinity in mixed‐tacticity polyhydroxybutyrates (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-03-30
    Description: Recently, the authors reported on the development of crystallinity in mixed‐tacticity polyhydroxybutyrates. Comparable values reported in the literature vary depending on the manner of determination, the discrepancies being partially attributable to scattering from paracrystalline portions of the material. These portions can be qualified by peak profile fitting or quantified by allocation of scattered X‐ray intensities. However, the latter requires a good quality of the former, which in turn must additionally account for peak broadening inherent in the measurement setup, and due to limited crystallite sizes and the possible presence of microstrain. Since broadening due to microstrain and paracrystalline order both scale with scattering vector, they are easily confounded. In this work, a method to directionally discern these two influences on the peak shape in a Rietveld refinement is presented. Allocating intensities to amorphous, bulk and paracrystalline portions with changing tactic disturbance provided internal validations of the obtained directional numbers. In addition, the correlation between obtained thermal factors and Young's moduli, determined in earlier work, is discussed.
    Description: A method to robustly determine paracrystalline contents from Rietveld‐refined powder X‐ray data is presented and discussed for the example of mixed‐tacticity polyhydroxybutyrates. image
    Keywords: 548 ; polyhydroxybutyrates ; mixed tacticity ; paracrystallinity ; Rietveld refinement ; thermal factors
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    Gravitationally Consistent Mean Barystatic Sea Level Rise From Leakage‐Corrected Monthly GRACE Data (2021)
    Details
    Publication Date: 2021-07-01
    Description: Gravitationally consistent solutions of the Sea Level Equation from leakage‐corrected monthly‐mean GFZ RL06 Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GRACE‐FO) Stokes coefficients reveal that barystatic sea level averaged over the whole global ocean was rising by 1.72 mm a−1 during the period April 2002 until August 2016. This rate refers to a truely global ocean averaging domain that includes all polar and semienclosed seas. The result corresponds to 2.02 mm a−1 mean barystatic sea level rise in the open ocean with a 1,000 km coastal buffer zone as obtained from a direct spatial integration of monthly GRACE data. The bias of +0.3 mm a−1 is caused by below‐average barystatic sea level rise in close proximity to coastal mass losses induced by the smaller gravitational attraction of the remaining continental ice and water masses. Alternative spherical harmonics solutions from CSR, JPL, and TU Graz reveal open‐ocean rates between 1.94 and 2.08 mm a−1, thereby demonstrating that systematic differences among the processing centers are much reduced in the latest release. We introduce in this paper a new method to approximate spatial leakage from the differences of two differently filtered global gravity fields. A globally constant and time‐invariant scale factor required to obtain full leakage from those filter differences is found to be 3.9 for GFZ RL06 when filtered with DDK3, and lies between 3.9 and 4.4 for other processing centers. Spatial leakage is estimated for every month in terms of global grids, thereby providing also valuable information of intrabasin leakage that is potentially relevant for hydrologic and hydrometeorological applications.
    Description: Plain Language Summary: Satellite gravimetry as realized with the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GRACE‐FO) missions is measuring tiny variations in the Earth's gravity field that are directly caused by divergent horizontal mass transports such as the melting of ice sheets and the corresponding discharge of melt water into the ocean basins. Between April 2002 and August 2016, this mass inflow caused sea level to rise by 1.72 mm each year as quantified from the latest GRACE reprocessing performed at our institute. The indirect observation principle of GRACE limits the spatial resolution so that highly localized mass loss signals are smeared out into the larger surrounding area, and possibly even from land into the ocean. We propose here a new method to quantify this so‐called spatial leakage from the difference of gravity fields smoothed with slightly different spatial filters. A scale factor is obtained from exploiting the availability of two independent methods to estimate the mass component of sea level rise: The first method spatially integrates over the global gravity fields in all regions away from the coasts, and the second method utilizes a (leakage‐corrected) mass distribution over the continents to calculate the gravitationally consistent distribution of water masses in all ocean basins. We estimate this scale factor as 3.9.
    Description: Key Points: Mean barystatic sea level rise is biased high by 0.3 mm a−1 when estimated with a 1,000 km coastal buffer zone. Fractional spatial leakage in monthly GRACE gravity fields is quantified with two differently strong DDK filters. Fractional leakage is scaled by a factor of 3.9 to make results from the Sea Level Equation consistent with open‐ocean integrations.
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: European Union http://dx.doi.org/10.13039/501100000780
    Description: German Research Foundation http://dx.doi.org/10.13039/501100001659
    Keywords: 526.7 ; time‐variable gravity ; barystatic sea level ; spatial leakage ; GRACE ; GRACE‐FO
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    Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu (2021)
    Details
    Publication Date: 2021-07-04
    Description: Rubble pile asteroids such as (162173) Ryugu have large bulk porosities, which are believed to result from void spaces in between the constituent boulders (macroporosity) as well as void spaces within the boulders themselves (microporosity). In general, both macroporosity and microporosity are estimated based on comparisons between the asteroid bulk density and both the bulk and grain density of meteorite analogs, and relatively large macroporosities are usually obtained. Here we use semiempirical models for the macroporosity of multicomponent mixtures to determine Ryugu's macroporosity based on the observed size‐frequency distribution (SFD) of boulders on the surface. We find that Ryugu's macroporosity can be significantly smaller than usually assumed, as the observed SFD allows for an efficient packing of boulders, resulting in a macroporosity of 16% ± 3%. Therefore, we confirm that Ryugu's high bulk porosity is a direct consequence of a very large boulder microporosity. Furthermore, using estimates of boulder microporosity of around 50% as derived from in situ measurements, the average grain density in boulders is 2,848 ± 152 kg m–3, similar to values obtained for CM and the Tagish lake meteorites. Ryugu's bulk porosity corresponding to the above values is 58%. Thus, the macroporosity of rubble pile asteroids may have been systematically overestimated in the past.
    Description: Plain Language Summary: The carbonaceous asteroid (162173) Ryugu formed from fragments which reaccreted after its parent body was disrupted by a catastrophic collision. Asteroids of this type are also known as rubble piles and the reaccumulation process is thought to be one of the causes for their large bulk porosity. We have applied mixing models to determine the amount of interboulder porosity taking the observed abundance of large and small boulders on the surface into account. We find that the relative abundances of differently sized boulders allow for a very efficient packing, such that interboulder porosity in Ryugu is rather small and only 16% ± 3%. This implies that a large part of Ryugu's total porosity must reside inside the boulders themselves. Using estimates of boulder intrinsic porosity, we furthermore constrain the average density of the boulder's constituent minerals to 2,848 ± 152 kg m−3, which is consistent with values measured for carbonaceous meteorites as collected on Earth. Thus, interboulder porosity of rubble pile asteroids may have been systematically overestimated in the past.
    Description: Key Points: Ryugu's large bulk porosity is distributed between intrinsic boulder microporosity and macroporosity due to void spaces in‐between boulders. We use the boulder size‐frequency distribution as observed on the surface together with mixing models to estimate Ryugu's macroporosity. We find that macroporosity is 16% ± 3%, indicating that Ryugu's large bulk porosity of close to 50% is governed by microporosity.
    Keywords: 523 ; Asteroids ; Ryugu ; Porosity ; Density
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    “GIS works!”—But why, how, and for whom? Findings from a systematic review (2021)
    Details
    Publication Date: 2021-06-27
    Description: This article presents the findings from systematically reviewing 26 empirical research studies published from 2005 to 2014 on the use of GIS for learning and teaching. By employing methods of narrative synthesis and qualitative content analysis, the study gives evidence about the state of knowledge of competence‐based GIS education. The results explain what factors and variables effect GIS learning in terms of technology use, major subject contents, learning contexts, and didactic and pedagogical aspects. They also show what facets of knowledge, process skills, and affect the research literature has investigated. The analysis of the type and quality of the methods used indicates that current GIS education research is a heterogeneous field that needs a systematic research framework for future efforts, according to empirical education research.
    Keywords: 526.0285 ; GIS
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    Diurnal Pumped‐Storage Operation Minimizes Methane Ebullition Fluxes From Hydropower Reservoirs (2021)
    Details
    Publication Date: 2021-06-28
    Description: Hydropower is considered green energy and promoted to reduce greenhouse warming. However, hydropower is typically generated using reservoirs and reservoirs are known to emit substantial amounts of the greenhouse gas methane (CH4) to the atmosphere. In many reservoirs ebullition is the dominant pathway of CH4 emission. We show that continuous diurnal pumped‐storage operation, which combines water pumping into the reservoir typically during the night and water drawdown during high demand of electricity, is beneficial for reducing CH4 ebullition associated with hydropower generation. This conclusion is based on ebullition fluxes and water levels measured over 3 months in Schwarzenbach reservoir located in Germany. The reservoir was managed using three modes of operation: (1) diurnal pumping and turbination, (2) no pumping and no turbination, and (3) diurnal turbination. Cross‐correlation analysis indicates that ebullition fluxes predominantly occur during diurnal water level decrease associated with turbination. Consistently, average ebullition fluxes of CH4 were negligible during Mode (2) and substantial during Modes (1) and (3). During Mode (3) the average CH4 ebullition flux was ~197 mg m−2day−1, ~12 times larger than during Mode (1) (16 mg m−2day−1). Our data indicate that overall CH4 ebullition is about 3 times larger during 51 days of operation consisting of 38 days of no turbination followed by 13 days of diurnal turbination than during 51 days of continuous diurnal pumped‐storage operation. This suggests that continuous diurnal pumped‐storage operation leads to reduced CH4 ebullition from reservoirs and is therefore advantageous compared to modes of operations involving long‐term, large‐amplitude turbination cycles.
    Description: Key Points: Draw down associated with turbination during pumped‐storage operation triggers ebullition in reservoirs Continuous pumped‐storage operation results in smaller ebullition than intensive pumping after long‐term storage Appropriate management strategies can contribute to a reduction of greenhouse gas emissions from reservoirs
    Description: Ministry of Science, Research and the Arts of the Federal State Baden‐Württemberg
    Keywords: 333.7 ; ebullition flux ; methane emissions ; reservoir
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    Simultaneous recording of filtration and respiration in marine organisms in response to short‐term environmental variability (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-06-16
    Description: Climate change imposes unusual long‐term trends in environmental conditions, plus some tremendous shifts in short‐term environmental variability, exerting additional stress on marine ecosystems. This paper describes an empirical method that aims to improve our understanding of the performance of benthic filter feeders experiencing changes in environmental conditions, such as temperature, on time scales of minutes to hours, especially during daily cycles or extreme events such as marine heatwaves or hypoxic upwelling. We describe the Fluorometer and Oximeter equipped Flow‐through Setup (FOFS), experimental design, and methodological protocols to evaluate the flood of data, enabling researchers to monitor important energy budget traits, including filtration and respiration of benthic filter‐feeders in response to fine‐tuned environmental variability. FOFS allows online recording of deviations in chlorophyll and dissolved oxygen concentrations induced by the study organism. Transparent data processing through Python scripts provides the possibility to adjust procedures to needs when working in different environmental contexts (e.g., temperature vs. pH, salinity, oxygen, biological cues) and with different filter‐feeding species. We successfully demonstrate the functionality of the method through recording responses of Baltic Sea blue mussels (Mytilus) during one‐day thermal cycles. This method practically provides a tool to help researchers exposing organisms to environmental variability for some weeks or months, to relate the observed long‐term performance responses to short‐term energy budget responses, and to explain their findings with the potential to generalize patterns. The method, therefore, allows a more detailed description of stress‐response relationships and the detection of species' tolerance limits.
    Description: Climate‐Biogeochemistry Interactions in the Tropical Ocean
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Exzellenzcluster Ozean der Zukunft http://dx.doi.org/10.13039/501100010783
    Description: GEOMAR Helmholtz‐Zentrum für Ozeanforschung Kiel http://dx.doi.org/10.13039/501100003153
    Description: Helmholtz‐Gemeinschaft http://dx.doi.org/10.13039/501100001656
    Description: Programme d’Investissements d’Avenir
    Description: Studienstiftung des Deutschen Volkes http://dx.doi.org/10.13039/501100004350
    Keywords: 578.77 ; benthic filter-feeders ; shallow-water marine habitats ; environmental changes ; monitoring energy budget responses
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    Transformation of Generation Processes From Small Runoff Events to Large Floods (2021)
    Details
    Publication Date: 2021-07-03
    Description: Mixture of runoff generation processes poses a challenge for predicting upper flood quantiles. We examined transformations of generation processes from all identifiable runoff events to frequent and upper tail floods for a large set of mesoscale catchments and observed a substantial change of the dominant processes. Two trajectories of transformation were detected. In regions where floods occur almost exclusively in winter the dominance of processes related to snowmelt consistently increases from small events to frequent and upper tail floods. In catchments characterized by frequent winter‐spring floods and occasional summer‐autumn flood events triggered by rare meteorological phenomena (e.g., Vb cyclones), processes that dominate upper tails are not adequately represented in the sample of frequent floods. Predictions of extremes and projections of flood changes might remain highly uncertain in the latter cases.
    Description: Plain Language Summary: Prediction of floods remains a challenging task for the engineering practice. Floods triggered by different physical mechanisms have contrasting statistical attributes. Mixture of these processes hinders reliable prediction of the largest floods. In this study we classified a large number of streamflow events observed in a wide range of German river basins according to their generation processes. We analyzed changes in the frequency of occurrence of different generation processes, from the smallest identifiable runoff events to annual floods to rarer events corresponding to larger river flows. Interestingly, for some river basins certain processes tend to consistently increase their frequency from small streamflow events to common and larger floods. In other cases, we observed an opposite tendency. Certain processes become less important for the generation of annual floods compared to small streamflow events but then dominate generation of the largest floods. This has important implications for our ability to predict extreme floods and their possible changes.
    Description: Key Points: We analyzed transformation of processes from small runoff events to larger floods using a process‐based framework for event characterization. A substantial transformation of the frequency of processes from small runoff events to frequent and upper tail floods is observed. Differences in trajectories of process transformation among catchments suggest regionally variable predictability of extremes.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: Helmholtz‐Zentrum für Umweltforschung (UFZ)
    Keywords: 551.489 ; flood origins ; event classification ; ordinary events ; annual floods ; upper tail floods ; process transformation
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    SAD: Verifying the scale, anisotropy and direction of precipitation forecasts (2021)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2021-07-20
    Description: One important attribute of meteorological forecasts is their representation of spatial structures. While several existing verification methods explicitly measure a structure error, they mostly produce a single value with no simple interpretation. Extending a recently developed wavelet‐based verification method, this study separately evaluates the predicted spatial scale, orientation and degree of anisotropy. The scale component has been rigorously tested in previous work and is known to assess the quality of a forecast similar to other, established methods. However, directional aspects of spatial structure are less frequently considered in the verification literature. Since important weather phenomena related to fronts, coastlines and orography have distinctly anisotropic signatures, their representation in meteorological models is clearly of interest. The ability of the new wavelet approach to accurately evaluate directional properties is demonstrated using idealized and realistic test cases from the MesoVICT project. A comparison of precipitation forecasts from several forecasting systems reveals that errors in scale and direction can occur independently and should be treated as separate aspects of forecast quality. In a final step, we use the inverse wavelet transform to define a simple post‐processing algorithm that corrects the structural errors. The procedure improves visual similarity with the observations, as well as the objective scores.
    Description: Forecasts of precipitation fields are difficult to evaluate due to their complex, intermittent spatial structure. The SAD forecast verification method uses wavelets to compare the scale (colours in the top row), anisotropy (bottom, arrow length) and preferred direction (bottom, arrow angles) of simulated and observed fields. The new approach is successfully tested using data from the MesoVICT community project.
    Description: German Research Foundation (DFG)
    Keywords: 551.5 ; MesoVICT ; precipitation forecasts ; structure error ; verification ; wavelets
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    Effect of waste landfill site on surface and ground water drinking quality (2021)
    Details
    Publication Date: 2021-06-28
    Description: Drinking water quality of surface and underground water within 1.34 km from a waste landfill site in Kumasi, Ghana was investigated. Physico‐chemical properties and heavy metal concentrations were analysed to determine water quality and pollution indices. It was found that turbidity of 83% of hand dug wells, 50% of the streams and 33% of boreholes were higher than World Health Organisation (WHO) standards for drinking water. Water quality index (WQI) showed that 25% of the water sources are of excellent quality, while 50%, 15% and 5% are good quality, poor quality, very poor quality and unsuitable for drinking, respectively. Heavy metal pollution index (HPI) indicated that the water sources were above the critical limit for drinking water (HPI 〉 100). Principal component analysis (PCA) revealed 75.30% and 70.88% of the total variance for the physico‐chemical parameters and heavy metals, respectively. The findings concluded that cadmium concentrations in all the water sources were extremely higher (0.0122–0.1090 mg/L) than WHO limit (0.003 mg/L), rendering them unwholesome for consumption.
    Keywords: 333.7 ; drinking water quality ; heavy metals pollution index ; landfill ; municipal solid waste ; principal component analysis ; water quality index
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    Spatiotemporal Variability of the Southern Annular Mode and its Influence on Antarctic Surface Temperatures (2021)
    Details
    Publication Date: 2021-07-03
    Description: The Southern Annular Mode (SAM) is the predominant atmospheric variability mode in the Southern Hemisphere. In this paper, we present the spatial variability results of the SAM pattern for the period 1979–2018. The SAM‐intrinsic pattern variability analysis is based on the principal component analysis (PCA), which is carried out for the ERA‐Interim 500 hPa geopotential height (GPH) data set. A spatiotemporally resolved data set of SAM pattern maps (PCA loadings) is derived by projecting monthly shifted sub‐sequences of SAM index values (PCA scores) on the corresponding GPH anomalies. The dominant SAM structure within single pattern fields is mapped automatically and can be interpreted as the Southern Hemisphere polar front. This data set allows an analysis of the geographical positions of the characteristic circumpolar SAM structure over four decades and shows considerable variability over space and time. Five different states of SAM patterns, which are associated with characteristic circulation anomalies during different phases of the study period, are identified. Station‐based Antarctic temperature anomalies can be synoptically explained by these circulation anomalies. The overall latitudinal trend of the SAM pattern indicates an intensification of the meridional structure, especially over the East Antarctic Southern Ocean. Furthermore, we show that the SAM pattern variability is significantly correlated with the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. Composites of 500 hPa GPH anomalies during the positive and negative phases of the respective indices indicate teleconnections with Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation, and this can explain latitudinal trends of the SAM pattern.
    Description: Key Points: We present a new approach to examine the spatiotemporal Southern Annular Mode pattern variability. Station‐based Antarctic temperature anomalies are related to different structures of the Southern Annular Mode. The trend pattern shows an increasing meridional structure and correlations with Pacific and Atlantic multidecadal oscillations.
    Description: DLR Management Board: Young Investigator Group Leader Program
    Keywords: 551.5 ; Southern Annular Mode ; SAM pattern variability ; Antarctic circulation variability ; Antarctic station temperature ; PDO ; AMO
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    Vegetation Trajectories and Shortwave Radiative Forcing Following Boreal Forest Disturbance in Eastern Siberia (2021)
    Details
    Publication Date: 2021-06-28
    Description: Major boreal forest disturbance and associated carbon emissions have been reported in the coldest region of the Northern Hemisphere. Related biophysical feedbacks to climate remain highly uncertain but might reduce warming effects expected from carbon emissions. This study quantifies albedo change after disturbance, primarily fires, in larch‐dominated forests around Yakutsk as compared to undisturbed areas with natural albedo variability, using satellite‐based time series. The related annual mean shortwave radiative forcing was −6.015 W/m2 for the 13 years following forest disturbance. It was highly negative during snow‐covered months (−3.738 to −13.638 W/m2), but positive (+5.441 W/m2) for the summer months in the first year after disturbance, decreasing afterward and also turning into a negative forcing after 5 years. Forcing by surface shortwave radiation must be considered to assess the impact of boreal forest disturbance on climate and additional feedbacks, such as increased permafrost thaw or transition to alternative ecosystem states.
    Description: Plain Language Summary: Boreal forests of northeastern Siberia are experiencing disturbances such as fires and permafrost degradation. These disturbances can trigger changes in biomass and heating dynamics resulting in major feedbacks to the local and regional climate. This study quantifies albedo, the ratio of reflected sunlight to incoming sunlight, in a larch‐dominated forest area in Siberia over a time span of 13 years after fire disturbance. Land surface albedo showed significant changes due to larch forest disturbance, which often recovered to a birch‐dominated forest. During summer months of the first 4 years after the forest fire, the decrease in albedo caused a local warming. For snow‐covered seasons, forest disturbance and the corresponding albedo change caused low local cooling directly after disturbance, and this cooling effect increased during the following decade.
    Description: Key Points: Major boreal forest cover disturbance in the coldest region of the Northern Hemisphere (Yakutsk, Siberia) during 2001–2014 resulted in a significant change in surface albedo Surface albedo change‐related mean annual surface shortwave radiative forcing was −6.015 W/m2 but varied with season and strongly decreased during the 13 years following disturbance Shortwave radiative forcing can be directly linked to a vegetation trajectory from deciduous needleleaf to broadleaf dominated forest
    Keywords: 333.7 ; albedo ; climate change ; wildfire ; vegetation trajectory ; larch ; radiative forcing
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    Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard (2021)
    Details
    Publication Date: 2021-07-01
    Description: The Svalbard margin represents one of the northernmost gas hydrate provinces worldwide. Vestnesa Ridge (VR) and Svyatogor Ridge (SR) west of Svalbard are two prominent sediment drifts showing abundant pockmarks and sites of seismic chimney structures. Some of these sites at VR are associated with active gas venting and were the focus of drilling and coring with the seafloor‐deployed MARUM‐MeBo70 rig. Understanding the nature of fluid migration and gas hydrate distribution requires (among other parameters) knowledge of the thermal regime and in situ gas and pore fluid composition. In situ temperature data were obtained downhole at a reference site at VR defining a geothermal gradient of ~78 mK m−1 (heat flow ~95 mW m−2). Additional heat probe data were obtained to describe the thermal regime of the pockmarks. The highest heat flow values were systematically seen within pockmark depressions and were uncorrelated to gas venting occurrences. Heat flow within pockmarks is typically ~20 mW m−2 higher than outside pockmarks. Using the downhole temperature data and gas compositions from drilling we model the regional base of the gas hydrate stability zone (BGHSZ). Thermal modeling including topographic effects suggest a BGHSZ up to 40 m deeper than estimated from seismic data. Uncertainties in sediment properties (velocity and thermal conductivity) are only partially explaining the mismatch. Capillary effects due to small sediment grain sizes may shift the free gas occurrence above the equilibrium BGHSZ. Changes in gas composition or pore fluid salinity at greater depth may also explain the discrepancy in observed and modeled BGHSZ.
    Description: Key Points: Heat flow variations across the Vestnesa and Svyatogor Ridges off Svalbard are correlated with seismic data showing gas hydrate BSRs. In situ temperatures were measured with the MARUM MeBo70 rig up to ~60 mbsf indicating a background thermal gradient of ~78°C/km. Heat flow is significantly higher within the pockmarks but is not correlated to the occurrence of gas venting.
    Description: Statoil http://dx.doi.org/10.13039/501100004342
    Description: CAGE
    Description: German Research Foundation (DFG)
    Keywords: 622.15 ; Svalbard margin ; heat flow ; gas hydrate ; pockmark ; MeBo drilling
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    Influence of Radiation on Evaporation Rates: A Numerical Analysis (2021)
    Details
    Publication Date: 2021-07-03
    Description: We present a fully coupled soil‐atmosphere model that includes radiation in the energy balance of the coupling conditions between the two domains. The model is able to describe evaporation processes under the influence of turbulence, surface roughness, and soil heterogeneities and focuses specifically on the influence of radiation on the mass and energy transport across the soil‐atmosphere interface. It is shown that evaporation rates are clearly dominated by the diurnal cycle of solar irradiance. During Stage‐I evaporation maximum temperatures are regulated due to evaporative cooling, but after a transition into Stage‐II evaporation, temperatures rise tremendously. We compare two different soil types, a coarser, sandy soil and a finer, silty soil, and analyze evaporation rates, surface temperatures, and net radiation for three different wind conditions. The influence of surface undulations on radiation and evaporation is analyzed and shows that radiation can lead to different local drying patterns in the hills and the valleys of the porous medium, depending on the height of the undulations and on the direction of the Sun. At last a comparison of lysimeter measurement data to the numerical examples shows a good match for measured and calculated radiation values but evaporation rates are still overestimated in the model. Possible reasons for the discrepancy between measurement and model data are analyzed and are found to be uncertainties about the parameters close to the interface, which are decisive for determining evaporation rates.
    Description: Key Points: We demonstrate the influence of radiation on evaporation rates. The influence of surface undulations on radiation and evaporation is analyzed. Comparison with experimental data shows the importance of interface processes.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: 551.5 ; fully coupled soil‐atmosphere model ; evaporation and radiation ; turbulence
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    Atmospheric and Oceanographic Signatures in the Ice Shelf Channel Morphology of Roi Baudouin Ice Shelf, East Antarctica, Inferred From Radar Data (2021)
    Details
    Publication Date: 2021-04-21
    Description: Ice shelves around Antarctica can provide back stress for outlet glaciers and control ice sheet mass loss. They often contain narrow bands of thin ice termed ice shelf channels. Ice shelf channel morphology can be interpreted through surface depressions and exhibits junctions and deflections from flowlines. Using ice flow modeling and radar, we investigate ice shelf channels in the Roi Baudouin Ice Shelf. These are aligned obliquely to the prevailing easterly winds. In the shallow radar stratigraphy, syncline and anticline stacks occur beneath the upwind and downwind side, respectively. The structures are horizontally and vertically coherent, except near an ice shelf channel junction where patterns change structurally with depth. Deeper layers truncate near basal incisions. Using ice flow modeling, we show that the stratigraphy is ∼9 times more sensitive to atmospheric variability than to oceanic variability. This is due to the continual adjustment toward flotation. We propose that syncline‐anticline pairs in the shallow stratigraphy are caused by preferential snow deposition on the windward side and wind erosion at the downwind side. This drives downwind deflection of ice shelf channels of several meters per year. The depth variable structures indicate formation of an ice shelf channel junction by basal melting. We conclude that many ice shelf channels are seeded at the grounding line. Their morphology farther seaward is shaped on different length scales by ice dynamics, the ocean, and the atmosphere. These processes act on finer (subkilometer) scales than are captured by most ice, atmosphere, and ocean models, yet the dynamics of ice shelf channels may have broader implications for ice shelf stability.
    Description: Plain Language Summary Ice flows from Antarctica's interior toward the coast. At the contact point between ice and ocean, the ice becomes afloat and forms fast‐flowing ice shelves. Snowfall continuously accumulates at the ice shelf surface, and at the ice shelf bottom the relatively warm ocean water can melt ice from below. Ice shelves sometimes exhibit a network of surface depressions resembling a river network. At the base, the depressions are accompanied by large incisions termed ice shelf channels. Using radar as a tool for echolocation, we investigate how the shape of this network is formed. We find that snow preferentially collects in the upwind side of the surface depressions. This makes ice shelf channels move to the downwind side. We also find that ice shelf channels can form junctions through localized ocean melting. This is important because it helps us to better understand how the Antarctic ice sheet interacts with the surrounding ocean.
    Description: Key Points The radar stratigraphy in ice shelves is 9 times more sensitive to variability in snow deposition than to variability in basal melting Some ice shelf channels at Roi Baudouin Ice Shelf deflect from flowlines; the radar stratigraphy reflects related processes Variable snow deposition causes slow deflection, and basal melting can form ice shelf channel junctions far from the grounding line
    Description: InBev Baillet Latour Antarctica Fellowship
    Description: Belgian Science Policy Office http://dx.doi.org/10.13039/501100002749
    Description: DFG Emmy Noether
    Description: Academy of Finland http://dx.doi.org/10.13039/501100002341
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: “Antarctic Research with comparative investigations in Arctic ice areas”
    Description: Academy of Finnland
    Description: Belgium Science Policy Office
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: InBev Baillet Latour Antarctica Fellowship
    Keywords: 551 ; glaciology ; geophysics ; Antarctica ; ice shelves ; ice‐ocean interaction ; ice shelf channels
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    Influence of Emission Sources and Tributaries on the Spatial and Temporal Patterns of Micropollutant Mixtures and Associated Effects in a Small River (2021)
    Details
    Publication Date: 2021-07-05
    Description: Organic micropollutants of anthropogenic origin in river waters may impair aquatic ecosystem health and drinking water quality. To evaluate micropollutant fate and turnover on a catchment scale, information on input source characteristics as well as spatial and temporal variability is required. The influence of tributaries from agricultural and urban areas and the input of wastewater were investigated by grab and Lagrangian sampling under base flow conditions within a 7.7‐km‐long stretch of the Ammer River (southwest Germany) using target screening for 83 organic micropollutants and 4 in vitro bioassays with environmentally relevant modes of action. In total, 9 pesticides and transformation products, 13 pharmaceuticals, and 6 industrial and household chemicals were detected. Further, aryl hydrocarbon receptor induction, peroxisome proliferator–activated receptor activity, estrogenicity, and oxidative stress response were measured in the river. The vast majority of the compounds and mixture effects were introduced by the effluent of a wastewater‐treatment plant, which contributed 50% of the total flow rate of the river on the sampling day. The tributaries contributed little to the overall load of organic micropollutants and mixture effects because of their relatively low discharge but showed a different chemical and toxicological pattern from the Ammer River, though a comparison to effect‐based trigger values pointed toward unacceptable surface water quality in the main stem and in some of the tributaries. Chemical analysis and in vitro bioassays covered different windows of analyte properties but reflected the same picture. Environ Toxicol Chem 2020;39:1382–1391. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: 551.9 ; Chemical analysis ; Bioassays ; Catchment scale ; Micropollutant mixtures ; Lagrangian sampling
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    Concepts for nondestructive and depth‐resolved X‐ray residual stress analysis in the near‐surface region of nearly single crystalline materials with mosaic structure (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-03-27
    Description: Two evaluation concepts for nondestructive depth‐resolved X‐ray residual stress analysis in the near‐surface region of materials with cubic symmetry and nearly single crystalline structure are introduced by simulated examples. Both concepts are based on the same data acquisition strategy, which consists in the determination of lattice‐spacing depth profiles along the ⟨hkl⟩ poles by stepwise sample rotation around the scattering vector. Segmentation of these profiles parallel to the sample surface provides the lattice strain state as a function of depth. The first evaluation concept extends the crystallite group method developed for materials with pronounced crystallographic texture by the feature of depth resolution and can be applied to samples with arbitrary orientation. The second evaluation concept, which adapts the linear regression approach of the sin2ψ method for the case of single crystalline materials, is restricted to samples with (001) orientation. The influence of the strain‐free lattice parameter a0 on residual stress analysis using both evaluation concepts is discussed on the basis of explicitly derived relations.
    Description: Two data evaluation concepts are proposed for nondestructive and depth‐resolved X‐ray residual stress analysis by means of energy‐dispersive diffraction on materials featuring cubic symmetry and a nearly single crystalline structure. image
    Keywords: 548 ; residual stress ; X‐ray diffraction ; depth‐resolved analysis ; mosaic crystals
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    X‐ray dichroism in polyimide caused by non‐resonant scattering (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-03-30
    Description: Dichroism is one of the most important optical effects in both the visible and the X‐ray range. Besides absorption, scattering can also contribute to dichroism. This paper demonstrates that, based on the example of polyimide, materials can show tiny dichroism even far from electronic resonances due to scattering. Although the effect is small, it can lead to a measurable polarization change and might have influence on highly sensitive polarimetric experiments.
    Description: Aligned molecules, for example in polyimide foils, lead to small dichroism even far from resonances, which can be revealed by high‐precision X‐ray polarimetry. image
    Keywords: 548 ; polyimide ; polarization ; X‐ray polarimetry ; wide‐angle scattering ; X‐ray dichroism
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    Elastic stiffness coefficients of thiourea from thermal diffuse scattering (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-03-27
    Description: The complete elastic stiffness tensor of thiourea has been determined from thermal diffuse scattering (TDS) using high‐energy photons (100 keV). Comparison with earlier data confirms a very good agreement of the tensor coefficients. In contrast with established methods to obtain elastic stiffness coefficients (e.g. Brillouin spectroscopy, inelastic X‐ray or neutron scattering, ultrasound spectroscopy), their determination from TDS is faster, does not require large samples or intricate sample preparation, and is applicable to opaque crystals. Using high‐energy photons extends the applicability of the TDS‐based approach to organic compounds which would suffer from radiation damage at lower photon energies.
    Description: The elastic stiffness coefficients of thiourea are determined from thermal diffuse scattering. image
    Keywords: 548 ; thermal diffuse scattering ; elastic stiffness ; thiourea
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    Increase in Population Exposure Due to Dry and Wet Extremes in India Under a Warming Climate (2021)
    Details
    Publication Date: 2021-06-30
    Description: Dry and wet extremes affect agricultural production, infrastructure, and socioeconomic well‐being of about 1.4 billion people in India. Despite the profound implications of dry and wet extremes, their changes in the observed and projected climate in India are not well quantified. Here, using the observations from multiple sources, we show that the area affected by dry extremes during the monsoon season (June–September) and water‐year (June–May) has significantly increased (~1% per decade; p value 〈 0.05) over the last six decades (1951–2015) in India. On the other hand, the area affected by wet extremes does not exhibit any significant trend over the same time period. Dry and wet extremes in the monsoon season are corroborated with the positive phase and negative phase of the sea surface temperature (SST) anomalies in the tropical Pacific Ocean (Niño 3.4 region). Global climate models (GCMs) project an increase of more than 25–30% (±3–6%) in the combined area affected by the dry and wet extremes in India by the end of the 21st century. The frequency of both dry and wet extreme years is also projected to increase in the majority of India (〉80%) under a warmer world if the global mean temperature rises above 1.5°C (or 2°C) from a preindustrial level. Moreover, the population exposed to the dry and wet extremes is likely to increase threefold under the projected 2°C warmer world. Therefore, limiting global mean temperature rise below 2°C can substantially reduce the area and population exposure due to dry and wet extremes in India.
    Description: Key Points: The area affected by dry extremes has significantly increased (~1% per decade) during 1951–2015 in India Climate models project increase in the combined area affected by the dry and wet extremes in India (25–30%) by the end of the 21st century The population exposed to the dry and wet extremes is likely to increase threefold under a (2°C) warmer world climate
    Description: Ministry of Earth Sciences (MoES) http://dx.doi.org/10.13039/501100001851
    Keywords: 551.6 ; dry extremes ; wet extremes ; CMIP5 ; population exposure ; SPEI ; India
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    Clouds, radiation, and atmospheric circulation in the present‐day climate and under climate change (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-07-03
    Description: By interacting with radiation, clouds modulate the flow of energy through the Earth system, the circulation of the atmosphere, and regional climate. We review the impact of cloud‐radiation interactions for the atmospheric circulation in the present‐day climate, its internal variability and its response to climate change. After summarizing cloud‐controlling factors and cloud‐radiative effects, we clarify the scope and limits of the Clouds On‐Off Klimate Model Intercomparison Experiment (COOKIE) and cloud‐locking modeling methods. COOKIE showed that the presence of cloud‐radiative effects shapes the circulation in the present‐day climate in many important ways, including the width of the tropical rain belts and the position of the extratropical storm tracks. Cloud locking, in contrast, identified how clouds affect internal variability and the circulation response to global warming. This includes strong, but model‐dependent, shortwave and longwave cloud impacts on the El‐Nino Southern Oscillation, and the finding that most of the poleward circulation expansion in response to global warming can be attributed to radiative changes in clouds. We highlight the circulation impact of shortwave changes from low‐level clouds and longwave changes from rising high‐level clouds, and the contribution of these cloud changes to model differences in the circulation response to global warming. The review in particular draws attention to the role of cloud‐radiative heating within the atmosphere. We close by raising some open questions which, among others, concern the need for studying the cloud impact on regional scales and opportunities created by the next generation of global storm‐resolving models. This article is categorized under: Climate Models and Modeling 〉 Knowledge Generation with Models
    Description: Clouds interact with radiation. We review the role of cloud‐radiation interactions in shaping the atmospheric circulation and thus regional climate and climate change. Figure from Blue Marble Collection of NASA Visible Earth.
    Description: U.S. Department of Energy's Office of Biological & Environmental Research
    Description: U.S. National Science Foundation
    Description: NERC CIRCULATES project
    Description: FONA: Research for Sustainable Development
    Description: German Ministry of Education and Research (BMBF) http://dx.doi.org/10.13039/501100002347
    Keywords: 551.5 ; circulation ; climate and climate change ; clouds ; global models ; radiation
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    Impact of Volcanic Aerosols on the Hydrology of the Asian Monsoon and Westerlies‐Dominated Subregions: Comparison of Proxy and Multimodel Ensemble Means (2021)
    Details
    Publication Date: 2021-07-03
    Description: Proxy‐model comparisons show large discrepancies in the impact of volcanic aerosols on the hydrology of the Asian monsoon region (AMR). This was mostly imputed to uncertainties arising from the use of a single model in previous studies. Here we compare two groups of CMIP5 multimodel ensemble mean (MMEM) with the tree‐ring‐based reconstruction Monsoon Asia Drought Atlas (MADA PDSI), to examine their reliability in reproducing the hydrological effects of the volcanic eruptions in 1300–1850 CE. Time series plots indicate that the MADA PDSI and the MMEMs agree on the significant drying effect of volcanic perturbation over the monsoon‐dominated subregion, while disparities exist over the westerlies‐dominated subregion. Comparisons of the spatial patterns suggest that the MADA PDSI and the MMEMs show better agreement 1 year after the volcanic eruption than in the eruption year and in subregions where more tree‐ring chronologies are available. The MADA PDSI and the CMIP5 MMEMs agree on the drying effect of volcanic eruptions in western‐East Asia, South Asian summer monsoon, and northern East Asian summer monsoon (EASM) regions. Model results suggest significant wetting effect in southern EASM and western‐South Asia, which agrees with the observed hydrological response to the 1991 Mount Pinatubo eruption. Analysis on model output from the Last Millennium Ensemble project shows similar hydrological responses. These results suggest that the CMIP5 MMEM is able to reproduce the impact of volcanic eruptions on the hydrology of the southern AMR.
    Description: Key Points: Proxy and multimodel ensemble means agree (disagree) on post volcanic hydro‐responses over the Asian monsoon (westerlies)‐dominated subregion. Better agreement of spatial hydrological patterns is suggested 1 year after the eruption and in subregions with more tree‐ring data. Multimodel ensemble means can reproduce the hydrological response to volcanic perturbations in the southern Asian monsoon region.
    Keywords: 551.5 ; volcanic aerosol ; monsoon‐dominated subregion ; westerlies‐dominated subregion ; proxy data ; multimodel ensemble mean ; hydrological index
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    The Combined Algae Test for the Evaluation of Mixture Toxicity in Environmental Samples (2021)
    Details
    Publication Date: 2021-07-05
    Description: The combined algae test is a 96‐well plate‐based algal toxicity assay with the green algae Raphidocelis subcapitata that combines inhibition of 24‐h population growth rate with inhibition of photosynthesis detected after 2 and 24 h with pulse‐amplitude modulated (PAM) fluorometry using a Maxi‐Imaging PAM. The combined algae test has been in use for more than a decade but has had limitations due to incompatibilities of the measurements of the 2 biological endpoints on the same microtiter plates. These limitations could be overcome by increasing growth rates and doubling times on black, clear‐bottom 96‐well plates by application of dichromatic red/blue light‐emitting diode illumination. Different robotic dosing approaches and additional data evaluation methods helped to further expand the applicability domain of the assay. The combined algae test differentiates between nonspecifically acting compounds and photosynthesis inhibitors, such as photosystem II (PSII) herbicides. The PSII herbicides acted immediately on photosynthesis and showed growth rate inhibition at higher concentrations. If growth was a similar or more sensitive endpoint than photosynthesis inhibition, this was an indication that the tested chemical acted nonspecifically or that a mixture or a water sample was dominated by chemicals other than PSII herbicides acting on algal growth. We fingerprinted the effects of 45 chemicals on photosynthesis inhibition and growth rate and related the effects of the single compounds to designed mixtures of these chemicals detected in water samples and to the effects directly measured in water samples. Most of the observed effects in the water samples could be explained by known photosystem II inhibitors such as triazines and phenylurea herbicides. The improved setup of the combined algae test gave results consistent with those of the previous method but has lower costs, higher throughput, and higher precision. Environ Toxicol Chem 2020;39:2496–2508. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Description: The combined algae test (CAT) allows cost‐efficient high‐throughput monitoring of chemicals and water samples for their algae toxicity with a diagnostic component to differentiate between the mixture effects of photosynthesis inhibitors and other chemicals.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: 551.9 ; Algae ; Aquatic toxicology ; Effects‐based monitoring ; Herbicide ; Mixture toxicology ; Photosynthesis inhibition
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    Sediment budgeting of short‐term backfilling processes: The erosional collapse of a Carolingian canal construction (2021)
    Details
    Publication Date: 2021-07-04
    Description: Sediment budgeting concepts serve as quantification tools to decipher the erosion and accumulation processes within a catchment and help to understand these relocation processes through time. While sediment budgets are widely used in geomorphological catchment‐based studies, such quantification approaches are rarely applied in geoarchaeological studies. The case of Charlemagne's summit canal (also known as Fossa Carolina) and its erosional collapse provides an example for which we can use this geomorphological concept and understand the abandonment of the Carolingian construction site. The Fossa Carolina is one of the largest hydro‐engineering projects in Medieval Europe. It is situated in Southern Franconia (48.9876°N, 10.9267°E; Bavaria, southern Germany) between the Altmühl and Swabian Rezat rivers. It should have bridged the Central European watershed and connected the Rhine–Main and Danube river systems. According to our dendrochronological analyses and historical sources, the excavation and construction of the Carolingian canal took place in AD 792 and 793. Contemporary written sources describe an intense backfill of excavated sediment in autumn AD 793. This short‐term erosion event has been proposed as the principal reason for the collapse and abandonment of the hydro‐engineering project. We use subsurface data (drillings, archaeological excavations, and direct‐push sensing) and geospatial data (a LiDAR digital terrain model (DTM), a pre‐modern DTM, and a 3D model of the Fossa Carolina] for the identification and sediment budgeting of the backfills. Dendrochronological findings and radiocarbon ages of macro remains within the backfills give clear evidence for the erosional collapse of the canal project during or directly after the construction period. Moreover, our quantification approach allows the detection of the major sedimentary collapse zone. The exceedance of the manpower tipping point may have caused the abandonment of the entire construction site. The spatial distribution of the dendrochronological results indicates a north–south direction of the early medieval construction progress. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Description: The sediment budgeting concept as erosion and accumulation quantification tool helps in understanding the abrupt backfilling of excavated material in the construction pit, which may have forced the abandonment of the Carolingian canal in southern Germany at the end of the year AD 793. The backfill sediments could be dated precisely through radiocarbon dating of macro remains and dendrochronology of excavated timbers. These timbers recovered in three different archaeological excavation trenches reveal a Carolingian construction progress from North to South.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: 551 ; Sediment budgeting ; Geomorphological modelling ; Backfill processes ; Geoarchaeology ; Fossa Carolina ; Early Middle Ages ; South Germany
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    Evidence for local carbon‐cycle perturbations superimposed on the Toarcian carbon isotope excursion (2021)
    Details
    Publication Date: 2021-07-05
    Description: A Jurassic negative carbon isotope excursion (CIE), co‐evolved with Toarcian Oceanic Anoxic Event (OAE) at ~183 Ma, is suggested to be linked to a global carbon‐cycle perturbation and is well documented for Toarcian terrestrial fossil woods and marine sediments around the globe. A theoretically coupled δ13Ccarb‐δ13Corg pattern due to such dubbed global carbon‐cycle event from the negative CIE in Dotternhausen Toarcian stratigraphic profile (southwest Germany) is unexpectedly disturbed by two‐step δ13Ccarb‐δ13Corg decoupling in which the last step, upper in the stratigraphic order, is of higher magnitude. However, the trigger(s) for these sudden decoupling disturbances are still poorly constrained. Here, connecting new carbon and oxygen isotope data with documentary lipid biomarkers shows that the global carbon cycle during the Toarcian OAE was disturbed by enhanced green sulfur bacteria (GSB) metabolisms and early diagenesis at local scales. The first step δ13Ccarb‐δ13Corg decoupling was induced in the initial stage of the GSB bloom. The second step of much larger δ13Ccarb‐δ13Corg decoupling arising from a GSB prosperity was, however, exaggerated by early diagenesis through the respiration of sulfate‐reducing bacteria (SRB). Paleo‐geographically distinct localities of the Tethys region show contrasting decoupled δ13Ccarb‐δ13Corg patterns, which implies that the second‐order carbon‐cycle perturbations have pervasively and independently impacted the global carbon event during the Toarcian OAE.
    Description: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Keywords: 551.9 ; carbon isotope excursion ; green sulfur bacteria ; local carbon cycling ; Toarcian ; δ13Ccarb‐δ13Corg decoupling
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    High spatio‐temporal resolution measurements of cohesive sediment erosion (2021)
    Details
    Publication Date: 2021-07-01
    Description: In this study, we present a novel approach to measure fundamental processes of cohesive sediment erosion. The experimental setup consists of a laboratory erosion flume (SETEG) and a photogrammetric method to detect sediment erosion (PHOTOSED). Detailed data are presented for three erosion experiments, which were conducted with a natural non‐cohesive/cohesive sediment mixture at increasing sediment depths (4, 8, 16 cm). In each experiment, the sediment was exposed to a set of incrementally increasing shear stresses and the erosion was measured dynamically, pixel‐based, and approximate to the process scale given the resolution of PHOTOSED. This enables us to distinguish between (i) individual emerging erosion spots caused by surface erosion and (ii) large holes torn open by detached aggregate chunks. Moreover, interrelated processes were observed, such as (iii) propagation of the erosion in the longitudinal and lateral direction leading to merging of disconnected erosion areas and (iv) progressive vertical erosion of already affected areas. By complementing the (bulk) erosion volume profiles with additional quantitative variables, which contain spatial information (erosion area, specific deepening, number of disconnected erosion areas), conclusions on the erosion behaviour (and the dominant processes) can be drawn without requiring qualitative information (such as visual observations). In addition, we provide figures indicating the spatio‐temporal erosion variability and the (bulk) erosion rates for selected time periods. We evaluate the variability by statistical quantities and show that significant erosion is mainly confined to only a few events during temporal progression, but then considerably exceeds the time‐averaged median of the erosion (factors between 7.0 and 16.0). Further, we point to uncertainties in using (bulk) erosion rates to assess cohesive sediment erosion and particularly the underlying processes. As a whole, the results emphasise the need to measure cohesive sediment erosion with high spatio‐temporal resolution to obtain reliable and robust information. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Description: The highly dynamic erosion progress is investigated for three experiments, which were conducted with a natural non‐cohesive/cohesive sediment mixture, using a photogrammetric method to detect sediment erosion (PHOTOSED). Given the high spatio‐temporal resolution of the measurements, fundamental and interrelated erosion processes are identified and the spatio‐temporal erosion variability over the surface is evaluated.
    Description: Ministry of Science, Research and Arts of the federal state of Baden‐Württemberg
    Keywords: 551.3 ; PHOTOSED ; SETEG ; cohesive sediments ; non‐cohesive/cohesive sediment mixtures ; photogrammetric measurements ; spatio‐temporal erosion variability
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    Bayesian Calibration and Validation of a Large‐Scale and Time‐Demanding Sediment Transport Model (2021)
    Details
    Publication Date: 2021-07-04
    Description: This study suggests a stochastic Bayesian approach for calibrating and validating morphodynamic sediment transport models and for quantifying parametric uncertainties in order to alleviate limitations of conventional (manual, deterministic) calibration procedures. The applicability of our method is shown for a large‐scale (11.0 km) and time‐demanding (9.14 hr for the period 2002–2013) 2‐D morphodynamic sediment transport model of the Lower River Salzach and for three most sensitive input parameters (critical Shields parameter, grain roughness, and grain size distribution). Since Bayesian methods require a significant number of simulation runs, this work proposes to construct a surrogate model, here with the arbitrary polynomial chaos technique. The surrogate model is constructed from a limited set of runs (n=20) of the full complex sediment transport model. Then, Monte Carlo‐based techniques for Bayesian calibration are used with the surrogate model (105 realizations in 4 hr). The results demonstrate that following Bayesian principles and iterative Bayesian updating of the surrogate model (10 iterations) enables to identify the most probable ranges of the three calibration parameters. Model verification based on the maximum a posteriori parameter combination indicates that the surrogate model accurately replicates the morphodynamic behavior of the sediment transport model for both calibration (RMSE = 0.31 m) and validation (RMSE = 0.42 m). Furthermore, it is shown that the surrogate model is highly effective in lowering the total computational time for Bayesian calibration, validation, and uncertainty analysis. As a whole, this provides more realistic calibration and validation of morphodynamic sediment transport models with quantified uncertainty in less time compared to conventional calibration procedures.
    Description: Key Points: We reduce a time‐demanding sediment transport model with a surrogate technique based on the arbitrary polynomial chaos expansion (aPC). Bayesian model calibration and validation in a fraction of computational time compared to conventional (manual, deterministic) methods. We achieve a more realistic calibration, a more successful validation, and valuable information in the form of uncertainty intervals.
    Description: German Research Foundation (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: 551 ; sediment transport modeling ; Lower River Salzach ; surrogate model ; arbitrary polynomial chaos expansion ; uncertainty analysis ; Bayesian updating
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    Machine Learning‐Based Prediction of Spatiotemporal Uncertainties in Global Wind Velocity Reanalyses (2021)
    Details
    Publication Date: 2021-07-03
    Description: The characterization of uncertainties in geophysical quantities is an important task with widespread applications for time series prediction, numerical modeling, and data assimilation. In this context, machine learning is a powerful tool for estimating complex patterns and their evolution through time. Here, we utilize a supervised machine learning approach to dynamically predict the spatiotemporal uncertainty of near‐surface wind velocities over the ocean. A recurrent neural network (RNN) is trained with reanalyzed 10 m wind velocities and corresponding precalculated uncertainty estimates during the 2012–2016 time period. Afterward, the neural network's performance is examined by analyzing its prediction for the subsequent year 2017. Our experiments show that a recurrent neural network can capture the globally prevalent wind regimes without prior knowledge about underlying physics and learn to derive wind velocity uncertainty estimates that are only based on wind velocity trajectories. At single training locations, the RNN‐based wind uncertainties closely match with the true reference values, and the corresponding intra‐annual variations are reproduced with high accuracy. Moreover, the neural network can predict global lateral distribution of uncertainties with small mismatch values after being trained only at a few isolated locations in different dynamic regimes. The presented approach can be combined with numerical models for a cost‐efficient generation of ensemble simulations or with ensemble‐based data assimilation to sample and predict dynamically consistent error covariance information of atmospheric boundary forcings.
    Description: Plain Language Summary: Machine learning is increasingly used for a wide range of applications in geosciences. In this study, we use an artificial neural network in the context of time series prediction. In particular, the goal is to use a neural network for learning spatial and temporal uncertainties that are associated with globally estimated wind velocities. Three well‐known wind velocity products are used for the time period 2012–2016 in different training, validation, and prediction scenarios. Our experiments show that a neural network can learn the prevailing global wind regimes and associate these with corresponding uncertainty estimates. Such a trained neural network can be used for different applications, for example, a cost‐efficient generation of ensemble simulations or for improving traditional data assimilation schemes.
    Description: Key Points: A recurrent neural network is set up to predict spatiotemporal uncertainties in wind velocity reanalyses. Global uncertainty maps can be derived from only few individual training locations. This method has benefits for time series prediction, ensemble simulations, and data assimilation.
    Keywords: 551.5 ; machine learning ; artificial neural network ; wind velocity ; atmospheric reanalysis ; ensemble simulation ; data assimilation
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    Sedimentological Evidence for Pronounced Glacial‐Interglacial Climate Fluctuations in NE Tibet in the Latest Pliocene to Early Pleistocene (2021)
    Details
    Publication Date: 2021-07-04
    Description: The intensification of Northern Hemisphere glaciation (iNHG) and uplift of the Tibetan Plateau have been argued to be among the main drivers of climate change in midlatitude Central Asia during the Pliocene/Pleistocene. While most proxy records that support this hypothesis are from regions outside the Tibetan Plateau (such as from the Chinese Loess Plateau), detailed paleoclimatic information for the plateau itself during that time has yet remained elusive. Here we present a temporally highly resolved (~500 years) sedimentological record from the Qaidam Basin situated on the northeastern Tibetan Plateau that shows pronounced glacial‐interglacial climate variability during the interval from 2.7 to 2.1 Ma. Glacial (interglacial) intervals are generally characterized by coarser (finer) grain size, minima (maxima) in organic matter content, and maxima (minima) in carbonate content. Comparison of our results with Earth's orbital parameters and proxy records from the Chinese Loess Plateau suggests that the observed climate fluctuations were mainly driven by changes in the Siberian High/East Asian winter monsoon system as a response to the iNHG. They are further proposed to be enhanced by the topography of the Tibetan Plateau and its impact on the position and intensity of the westerlies.
    Description: Key Points: Pronounced glacial‐interglacial climate fluctuations on the NE Tibetan Plateau during the latest Pliocene and early Pleistocene. Changes in East Asian Winter Monsoon and the position of the westerlies influenced sediment transport on the NE Tibetan Plateau. Intensification of Northern Hemisphere glaciation amplified climate fluctuations on the NE Tibetan Plateau.
    Description: German Research Foundation (DFG
    Keywords: 551.7 ; loss on ignition ; EMMA ; SEM ; dust ; Asian monsoon ; Westerlies
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    Fast fitting of reflectivity data of growing thin films using neural networks (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-07-03
    Description: X‐ray reflectivity (XRR) is a powerful and popular scattering technique that can give valuable insight into the growth behavior of thin films. This study shows how a simple artificial neural network model can be used to determine the thickness, roughness and density of thin films of different organic semiconductors [diindenoperylene, copper(II) phthalocyanine and α‐sexithiophene] on silica from their XRR data with millisecond computation time and with minimal user input or a priori knowledge. For a large experimental data set of 372 XRR curves, it is shown that a simple fully connected model can provide good results with a mean absolute percentage error of 8–18% when compared with the results obtained by a genetic least mean squares fit using the classical Parratt formalism. Furthermore, current drawbacks and prospects for improvement are discussed.
    Description: Artificial neural networks trained with simulated data are shown to correctly and quickly determine film parameters from experimental X‐ray reflectivity curves.
    Keywords: 548 ; X‐ray reflectivity ; machine learning ; organic semi‐conductors ; neural networks
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    Self‐Validating Deep Learning for Recovering Terrestrial Water Storage From Gravity and Altimetry Measurements (2021)
    Details
    Publication Date: 2021-07-03
    Description: Quantifying and monitoring terrestrial water storage (TWS) is an essential task for understanding the Earth's hydrosphere cycle, its susceptibility to climate change, and concurrent impacts for ecosystems, agriculture, and water management. Changes in TWS manifest as anomalies in the Earth's gravity field, which are routinely observed from space. However, the complex underlying distribution of water masses in rivers, lakes, or groundwater basins remains elusive. We combine machine learning, numerical modeling, and satellite altimetry to build a downscaling neural network that recovers simulated TWS from synthetic space‐borne gravity observations. A novel constrained training is introduced, allowing the neural network to validate its training progress with independent satellite altimetry records. We show that the neural network can accurately derive the TWS in 2019 after being trained over the years 2003 to 2018. Further, we demonstrate that the constrained neural network can outperform the numerical model in validated regions.
    Description: Plain Language Summary: Continuous monitoring of the distribution and movement of continental water masses is essential for understanding the Earth's global water cycle, its susceptibility to climate change, and for risk assessments of ecosystems, agriculture, and water management. Changes of continental water masses are encoded as coarse blob‐like patterns in satellite observations of the Earth's gravity field. Focusing on the South American continent, we introduce a self‐validating artificial neural network to recover detailed and accurate spatiotemporal information of continental water masses from such gravity field observations.
    Description: Key Points: South American terrestrial water storage (TWS) is derived from satellite gravity observations with deep learning. A neural network accurately predicts multiscale monthly TWS anomalies in 2019 based on training data from 2003 to 2018. A data assimilation‐like training is introduced, allowing the neural network to validate itself with independent altimetry records.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100001656
    Description: Initiative and Networking Fund of the Helmholtz Association
    Keywords: 550.28 ; terrestrial water storage ; hydrology modeling ; hydrosphere ; deep learning ; downscaling ; artificial intelligence
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    Evolving temperature field in a fossil subduction channel during the transition from subduction to collision (Tauern Window, Eastern Alps) (2021)
    Details
    Publication Date: 2021-07-05
    Description: We investigate the evolution of the three‐dimensional thermal structure of a palaeo‐subduction channel exposed in the Penninic units of the central Tauern Window (Eastern Alps). Structural and petrological observations reveal a sheath fold with an amplitude of some 20 km that formed under high‐P conditions (~2 GPa). The fold is a composite structure that isoclinally folded the thrust of an ophiolitic nappe derived from Alpine Tethys Ocean onto a unit of the distal European continental margin, also affected by the high‐P conditions. This structural assemblage is preserved between two younger domes at either end of the Tauern Window. The domes deform isograds of the T‐dominated Barrovian metamorphism that itself overprints the high‐P metamorphism partly preserved in the sheath fold. Using Raman spectroscopy on carbonaceous material (RSCM), we are able to distinguish peak‐temperature domains related to the original subduction metamorphism from domains associated with the later temperature‐dominated (Barrovian) metamorphism. The distribution of RSCM temperatures in the Barrovian domain indicates a lateral and vertical decrease of peak temperature with increasing distance from the centres of the thermal domes. This represents a downward increase of palaeo‐temperature, in line with previous studies. However, we observe the opposite palaeo‐temperature trend in the lower limb of the sheath fold, namely an upward increase. We interpret this inverted palaeo‐temperature domain as the relic of a subduction‐related temperature field. Towards the central part of the sheath fold's upper limb, RSCM temperatures increase to a maximum of ~520°C. Further upsection in the hangingwall of the sheath fold, palaeo‐peak temperatures decrease to where they are indistinguishable from the peak temperatures of the overprinting Barrovian metamorphism. Peak‐temperature contours of the subduction‐related metamorphism are oriented roughly parallel to the folded nappe contacts and lithological layering. The contours close towards the northern, western and eastern parts of the fold, resulting in an eye‐shaped, concentric pattern in cross‐section. The temperature contour geometry therefore mimics the fold geometry itself, indicating that these contours were also folded in a sheath‐like manner. We propose that this sheath‐like pattern is the result of a two‐stage process that reflects a change of the mode of nappe formation in the subduction zone from thrusting to fold nappe formation. First, thrusting of a hot oceanic nappe onto a colder continental nappe created an inverted peak‐thermal gradient. Second, sheath folding of this composite nappe structure together with the previously established peak‐temperature pattern during exhumation. This pattern was preserved because temperatures decreased during retrograde exhumation metamorphism and remained less than the subduction‐related peak temperatures during the later Barrovian overprint. The fold ascended with diapir‐like kinematics in the subduction channel.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: 552.4 ; RSCM ; sheath fold ; subduction metamorphism ; subduction‐exhumation channel ; temperature field
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    Turritelline mass accumulations from the Lower Miocene of southern Germany: implications for tidal currents and nutrient transport within the North Alpine Foreland Basin (2021)
    Details
    Publication Date: 2021-03-30
    Description: The mass occurrence of turritelline gastropod shells from the Lower Miocene of southern Germany allows for detailed studies of their palaeoecology, transport mechanisms, preservation potentials and the reconstruction of nutrient regimes. Changes in the fabric of the gastropod‐dominated beds are used to reconstruct a generally deepening environment corresponding to the Lower Miocene transgression within the Upper Molasse Sea of the North Alpine Foreland Basin. The sedimentary succession ranges from chaotically arranged, densely packed and near‐shore transported; wave‐influenced deposits showing bimodal shell orientations; more widely dispersed shells showing a uni‐directional orientation; and dispersed shells showing diverse orientations. The shells often show damage to the apex and aperture though it is not clear whether this is due to predation events, pagurisation or abrasion due to transport. An outstanding feature is the replacement of aragonite shells by calcite leading to internal vugs as well as modulating the outer shell surface morphology. The high density of turritelline gastropods indicates a nutrient‐rich palaeoenvironment at the northern edge of the Molasse Sea.
    Description: Gesellschaft zur Förderung des Naturkundemuseums Stuttgart
    Keywords: 560 ; Molasse ; orientation data ; palaeoecology ; taphonomy ; turritelline gastropods
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    Testing the preservation potential of early diagenetic dolomites as geochemical archives (2021)
    Details
    Publication Date: 2021-07-05
    Description: Early marine diagenetic dolomite is a rather thermodynamically‐stable carbonate phase and has potential to act as an archive of marine porewater properties. However, the variety of early to late diagenetic dolomite phases that can coexist within a single sample can result in extensive complexity. Here, the archive potential of early marine dolomites exposed to extreme post‐depositional processes is tested using various types of analyses, including: petrography, fluid inclusion data, stable δ13C and δ18O isotopes, 87Sr/86Sr ratios, and U‐Pb age dating of various dolomite phases. In this example, a Triassic carbonate platform was dissected and overprinted (diagenetic temperatures of 50 to 430°C) in a strike‐slip zone in Southern Spain. Eight episodes of dolomitization, a dolostone cataclasite and late stage meteoric/vadose cementation were recognized. The following processes were found to be diagenetically relevant: (i) protolith deposition and fabric‐preservation, and marine dolomitization of precursor aragonite and calcite during the Middle–Late Triassic; (ii) intermediate burial and formation of zebra saddle dolomite and precipitation of various dolomite cements in a Proto‐Atlantic opening stress regime (T ca 250°C) during the Early–Middle Jurassic; (iii) dolomite cement precipitation during early Alpine tectonism, rapid burial to ca 15 km, and high‐grade anchizone overprint during Alpine tectonic evolution in the Early Eocene to Early Miocene; (iv) brecciation of dolostones to cataclasite during the onset of the Carboneras Fault Zone activity during the Middle Miocene; and (v) late‐stage regression and subsequent meteoric overprint. Data shown here document that, under favourable conditions, early diagenetic marine dolomites and their archive data may resist petrographic and geochemical resetting over time intervals of 108 or more years. Evidence for this preservation includes preserved Late Triassic seawater δ13CDIC values and primary fluid inclusion data. Data also indicate that oversimplified statements based on bulk data from other petrographically‐complex dolomite archives must be considered with caution.
    Description: DFG http://dx.doi.org/10.13039/501100001659
    Keywords: 551.9 ; Diagenesis ; dolomite ; dolomitization ; fluid inclusions ; geochemistry ; petrography ; tectonic overprint ; U‐Pb dating
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    Magmatic and Sedimentary Structure beneath the Klyuchevskoy Volcanic Group, Kamchatka, From Ambient Noise Tomography (2021)
    Details
    Publication Date: 2021-07-03
    Description: The Klyuchevskoy Volcanic Group is a cluster of the world's most active subduction volcanoes, situated on the Kamchatka Peninsula, Russia. The volcanoes lie in an unusual off‐arc position within the Central Kamchatka Depression (CKD), a large sedimentary basin whose origin is not fully understood. Many gaps also remain in the knowledge of the crustal magmatic plumbing system of these volcanoes. We conducted an ambient noise surface wave tomography, to image the 3‐D shear wave velocity structure of the Klyuchevskoy Volcanic Group and CKD within the surrounding region. Vertical component cross correlations of the continuous seismic noise are used to measure interstation Rayleigh wave group and phase traveltimes. We perform a two‐step surface wave tomography to model the 3‐D Vsv velocity structure. For each inversion stage we use a transdimensional Bayesian Monte Carlo approach, with coupled uncertainty propagation. This ensures that our model provides a reliable 3‐D velocity image of the upper 15 km of the crust, as well as a robust assessment of the uncertainty in the observed structure. Beneath the active volcanoes, we image small slow velocity anomalies at depths of 2–5 km but find no evidence for magma storage regions deeper than 5 km—noting the 15 km depth limit of the model. We also map two clearly defined sedimentary layers within the CKD, revealing an extensive 8 km deep sedimentary accumulation. This volume of sediments is consistent with the possibility that the CKD was formed as an Eocene‐Pliocene fore‐arc regime, rather than by recent (〈2 Ma) back‐arc extension.
    Description: Plain Language Summary: The Klyuchevskoy Volcanic Group is a cluster of 13 volcanoes on the Kamchatkan corner of the Pacific ring of fire. The volcanoes regularly produce large eruptions, but good knowledge of the magma plumbing system beneath the surface is still lacking. Why the Klyuchevskoy Volcanic Group volcanoes lie in the location they do, in a large low‐lying depression, is also unexplained. We undertook a seismic experiment and used the data to produce a 3‐D velocity image of the subsurface beneath the volcanoes and the depression. We found that small regions of slow seismic velocity are located beneath the active volcanoes, at 2–5 km depth below sea level. This slower velocity is probably caused by magma lying within the porous fracture spaces in this rock. The seismic velocities are much faster beneath the dormant volcanoes, suggesting they have no magma beneath them. With our velocity image, we also find that the Central Kamchatka Depression is very deep, filled with over 8 km of sediments. This supports an idea that the sediments accumulated as a fore‐arc basin over many millions of years, since 40 Ma, when the active line of volcanoes was found 100 km to the west.
    Description: Key Points: Three‐dimensional shear velocity structure of the Klyuchevskoy area was determined using coupled transdimensional Monte Carlo inversions. Slow velocity anomalies suggest magma storage beneath active volcanoes at 2–5 km depth (below sea level) but not in the midcrust. Sediments filling the Central Kamchatka Depression are 8 km deep, consistent with an origin of the depression as a fore‐arc basin.
    Description: European Union Horizon 2020 Research and Innovation Programme http://dx.doi.org/10.13039/501100007601
    Description: Russian Ministry of Education and Science http://dx.doi.org/10.13039/501100003443
    Description: Alexander von Humboldt Foundation http://dx.doi.org/10.13039/100005156
    Keywords: 551.1 ; tomography ; Central Kamchatka Depression ; transdimensional ; Bayesian ; ambient noise ; Klyuchevskoy Volcanic Group
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    Probabilistic Models Significantly Reduce Uncertainty in Hurricane Harvey Pluvial Flood Loss Estimates (2021)
    Details
    Publication Date: 2021-04-22
    Description: Pluvial flood risk is mostly excluded in urban flood risk assessment. However, the risk of pluvial flooding is a growing challenge with a projected increase of extreme rainstorms compounding with an ongoing global urbanization. Considered as a flood type with minimal impacts when rainfall rates exceed the capacity of urban drainage systems, the aftermath of rainfall‐triggered flooding during Hurricane Harvey and other events show the urgent need to assess the risk of pluvial flooding. Due to the local extent and small‐scale variations, the quantification of pluvial flood risk requires risk assessments on high spatial resolutions. While flood hazard and exposure information is becoming increasingly accurate, the estimation of losses is still a poorly understood component of pluvial flood risk quantification. We use a new probabilistic multivariable modeling approach to estimate pluvial flood losses of individual buildings, explicitly accounting for the associated uncertainties. Except for the water depth as the common most important predictor, we identified the drivers for having loss or not and for the degree of loss to be different. Applying this approach to estimate and validate building structure losses during Hurricane Harvey using a property level data set, we find that the reliability and dispersion of predictive loss distributions vary widely depending on the model and aggregation level of property level loss estimates. Our results show that the use of multivariable zero‐inflated beta models reduce the 90% prediction intervalsfor Hurricane Harvey building structure loss estimates on average by 78% (totalling U.S.$3.8 billion) compared to commonly used models.
    Description: Key Points Recent severe pluvial flood events highlight the need to integrate pluvial flooding in urban flood risk assessment Probabilistic models provide reliable estimation of pluvial flood loss across spatial scales Beta distribution model reduces the 90% prediction interval for Hurricane Harvey building loss by U.S.$3.8 billion or 78%
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: NSF GRFP
    Description: Fulbright Doctoral Program
    Keywords: 551.5 ; pluvial flooding ; loss modeling ; urban flooding ; probabilistic ; Hurricane Harvey ; climate change adaptation
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    How dark is a river? Artificial light at night in aquatic systems and the need for comprehensive night‐time light measurements (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-06-27
    Description: Freshwater ecosystems are hotspots of biodiversity. They are of major importance for humans because they provide vital ecosystem services. However, as humans tend to settle near freshwaters and coastal areas, these ecosystems are also over‐proportionally affected by anthropogenic stressors. Artificial light at night can occur as a form of environmental pollution, light pollution. Light pollution affects large areas on a worldwide scale, is growing exponentially in radiance and extent and can have diverse negative effects on flora, fauna and on human health. While the majority of ecological studies on artificial light at night covered terrestrial systems, the studies on aquatic light pollution have unraveled impact on aquatic organisms, ecosystem functions as well as land‐water‐interactions. Although monitoring of light pollution is routinely performed from space and supported by ground‐based measurements, the extent and the amount of artificial light at night affecting water bodies is still largely unknown. This information, however, is essential for the design of future laboratory and field experiments, to guide light planners and to give recommendations for light pollution regulations. We analyze this knowledge gap by reviewing night‐time light measurement techniques and discuss their current obstacles in the context of water bodies. We also provide an overview of light pollution studies in the aquatic context. Finally, we give recommendations on how comprehensive night‐time light measurements in aquatic systems, specifically in freshwater systems, should be designed in the future. This article is categorized under: Water and Life 〉 Stresses and Pressures on Ecosystems Water and Life 〉 Conservation, Management, and Awareness Water and Life 〉 Methods
    Description: Artificial light at night can occur as a form of environmental pollution, light pollution, which also affects aquatic systems. We identify a knowledge gap of insufficient data regarding the status quo of aquatic light pollution and provide a route to fill this gap with in‐situ measurements. image
    Description: European Cooperation in Science and Technology http://dx.doi.org/10.13039/501100000921
    Description: Leibniz Association http://dx.doi.org/10.13039/501100001664
    Description: Leibniz‐Institute of Freshwater Ecology and Inland Fisheries
    Keywords: 333.91 ; ALAN ; artificial light at night ; light measurement ; light pollution
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    Global Response Patterns of Major Rainfed Crops to Adaptation by Maintaining Current Growing Periods and Irrigation (2021)
    Details
    Publication Date: 2021-07-03
    Description: Increasing temperature trends are expected to impact yields of major field crops by affecting various plant processes, such as phenology, growth, and evapotranspiration. However, future projections typically do not consider the effects of agronomic adaptation in farming practices. We use an ensemble of seven Global Gridded Crop Models to quantify the impacts and adaptation potential of field crops under increasing temperature up to 6 K, accounting for model uncertainty. We find that without adaptation, the dominant effect of temperature increase is to shorten the growing period and to reduce grain yields and production. We then test the potential of two agronomic measures to combat warming‐induced yield reduction: (i) use of cultivars with adjusted phenology to regain the reference growing period duration and (ii) conversion of rainfed systems to irrigated ones in order to alleviate the negative temperature effects that are mediated by crop evapotranspiration. We find that cultivar adaptation can fully compensate global production losses up to 2 K of temperature increase, with larger potentials in continental and temperate regions. Irrigation could also compensate production losses, but its potential is highest in arid regions, where irrigation expansion would be constrained by water scarcity. Moreover, we discuss that irrigation is not a true adaptation measure but rather an intensification strategy, as it equally increases production under any temperature level. In the tropics, even when introducing both adapted cultivars and irrigation, crop production declines already at moderate warming, making adaptation particularly challenging in these areas.
    Description: Plain Language Summary: Global warming affects yields of grain crops, which are at the base of human diets. We use crop models to quantify its impacts on global crop production and to assess how adaptation could compensate for the adverse effects. We find that up to 2 K of increased temperature production can be maintained at the current level by using new cultivars, selected to maintain current growing period length under warming. Irrigation, as another management strategy, is shown to have the potential to increase yields in dry regions if water is available. However, models do not indicate that irrigation reduces the crops' sensitivity to warming. We find large differences in the yield response to warming and adaptation across climatic regions. While continental and temperate regions may benefit from higher temperatures but also show sizable adaptation potentials, tropical and arid regions show largest temperature impacts and smaller adaptation potentials. After all, these two crop management options appear effective to balance the effects of moderate warming but cannot fully compensate impacts above 2 K of warming.
    Description: Key Points: Without agronomic adaptation, the dominant effect of temperature increase is to shorten growing periods and to reduce yields and production. Adaptation via cultivars that maintain current growing periods under warming can compensate global production losses up to 2 K. Irrigation would act as intensification rather than true adaptation, as it hardly affects the sensitivity of crop yields to warming.
    Description: Early Postdoctoral Mobility Fellowship http://dx.doi.org/10.13039/501100001711
    Description: 7th Framework Programme Early http://dx.doi.org/10.13039/100013273
    Description: MACMIT project
    Description: BioNex Project
    Description: University of Chicago Center for Robust Decision‐making on Climate and Energy Policy http://dx.doi.org/10.13039/100006445
    Keywords: 631.5 ; 333.913 ; temperature increase ; crop yield ; adaptation ; growing period ; irrigation ; crop model
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    Improved understanding of dynamic water and mass budgets of high‐alpine karst systems obtained from studying a well‐defined catchment area (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-06-16
    Description: Large areas of Europe, especially in the Alps, are covered by carbonate rocks and in many alpine regions, karst springs are important sources for drinking water supply. Because of their high variability and heterogeneity, the understanding of the hydrogeological functioning of karst aquifers is of particular importance for their protection and utilisation. Climate change and heavy rainfall events are major challenges in managing alpine karst aquifers which possess an enormous potential for future drinking water supply. In this study, we present research from a high‐alpine karst system in the UNESCO Biosphere Reserve Großes Walsertal in Austria, which has a clearly defined catchment and is drained by only one spring system. Results show that (a) the investigated system is a highly dynamic karst aquifer with distinct reactions to rainfall events in discharge and electrical conductivity; (b) the estimated transient atmospheric CO2 sink is about 270 t/a; (c) the calculated carbonate rock denudation rate is between 23 and 47 mm/1000a and (d) the rainfall‐discharge behaviour and the internal flow dynamics can be successfully simulated using the modelling package KarstMod. The modelling results indicate the relevance of matrix storage in determining the discharge behaviour of the spring, particularly during low‐flow periods. This research and the consequent results can contribute and initiate a better understanding and management of alpine karst aquifers considering climate change with more heavy rainfall events and also longer dry periods.
    Description: The investigated karst system contributes to the transient atmospheric CO2 sink with about 270 t/a. Carbonate denudation rates vary between 23 and 47 mm/1000a. Rainfall‐discharge modelling results indicate the importance of matrix storage particularly during low‐flow periods. image
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: FP7 People: Marie‐Curie Actions http://dx.doi.org/10.13039/100011264
    Keywords: 551.49 ; CO2 sink ; denudation rate ; groundwater ; hydrochemical variability ; karst spring ; rainfall‐discharge model
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    Laufzeiten und Amplituden der Phasen SKS und SKKS und die Struktur des äußeren Erdkerns (2021)
    Selbstverlag
    In:  Autorenexemplar
    Details
    Publication Date: 2021-03-29
    Description: Die Laufzeitdifferenz zwischen den beiden Kernphasen SKS und SKKS wird hauptsächlich durch die unterschiedlichen Laufwege im äußeren Kern bestimmt; bis zur Kern-Mantel-Grenze laufen sie durch gleiche bzw. ähnliche Bereiche im Mantel. Laufzeitdifferenzen zwischen SKS und SKKS wurden in zwei Arbeiten zur Bestimmung der radialsymmetrischen Geschwindigkeitsstruktur des äußeren Kerns benutzt (HaIes & Roberts 1971, Kind & Müller 1977). In der Arbeit von Kind & Müller (1977) wurden aber vor allem die Amplitudenverhältnisse SKS/SKKS interpretiert und aus Abweichungen gegenüber bekannten Erdmodellen das Modell N20A für den äußeren Kern hergeleitet, das für den Tiefenbereich von 3600 - 4100 km eine Zone mit einer anomalen Geschwindigkeitsstruktur vorschlägt. lm Rahmen dieser Diplomarbeit werden die damaligen Ergebnisse der Untersuchung der Struktur des äußeren Kerns mit Differenzlaufzeiten SKKS-SKS und Amplitudenverhältnissen SKS/SKKS an Hand von 10 neu zur Verfügung stehenden Beben überprüft. Dafür wurden die LP-Seismogramme von WWSSN-Registrierungen digitalisiert und in Radial- und Transversal-Komponenten rotiert.Mit diesen neuen Daten konnte ein radialsymmetrischer Aufbau des äußeren Erdkerns mit einer glatten Geschwindigkeitsstruktur, wie von Dziewonski & Anderson (1981) mit dem Modell PREM vorgeschlagen, bestätigt werden. Das radialsymmetrische Modell N20A konnte mit den neuen Daten nicht bestätigt werden. Lediglich für den Laufweg der SKSund SKKS-Strahlen von Tonga-Fidschi nach Amerika wurden anomale Differenzlaufzeiten und anomale Amplitudenverhältnisse gefunden. Die hier nur regional anomalen Daten können weder mit PREM noch mit anderen radialsymmetrischen Erdkernmodellen wie N20A erklärt werden, sondern sind als Effekte von lateralen Inhomogenitäten zu interpretieren. Einige überlegungen sprechen dafür, diese lateralen Inhomogenitäten im Mantel als Zonen mit einer erniedrigten seismischen Geschwindigkeit zu suchen. Neben diesen Untersuchungen mit S-Wellen wird gezeigt, daß N20A im Gegensatz zu PREM auch beobachtete P4KPab-Laufzeiten nicht bestätigen kann.
    Description: research
    Keywords: e-docs::Geophysik ; Seismologie ; seismische Geschwindigkeiten ; Erdkern ; Erdmantel ; laterale Inhomogenitäten ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
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    Geologische Specialkarte des Grossherzogthums Hessen und der angrenzenden Landesgebiete im Maassstabe von 1: 50000 / Mittelrheinischer Geologischer Verein: Section Alsfeld (2021)
    Jonghaus, Darmstadt
    In:  SUB Göttingen | 8 MIN II, 3080:1,2
    Details
    Publication Date: 2021-06-15
    Description: Geologische Karte 1: 50 000 mit Erläuterungen. Section Alsfeld der topographischen Karte des Kurfürstenthum Hessen. Digitalisat des FID GEO (Fachinformationsdienst Geowissenschaften der festen Erde), erstellt durch das GDZ (Göttinger Digitalisierungszentrum), Karte aus dem Bestand der SUB Göttingen. Koordinaten Vorlage: Nullmeridian Ferro E 27 40 - E 27 60 N 50 48 - N 36
    Description: map
    Description: DFG, SUB Göttingen
    Keywords: 554.3 ; 912 ; Geologische Karte ; Alsfeld ; FID-GEO-DE-7
    Language: German
    Type: map_digi
    Format: 41
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    A High‐Resolution Paleosecular Variation Record for Marine Isotope Stage 6 From Southeastern Black Sea Sediments (2021)
    Details
    Publication Date: 2021-07-21
    Description: A full‐vector paleosecular variation (PSV) record (inclination, declination, and relative paleointensity) from the pen‐ultimate glacial (130–180 ka) could be constructed from a total of 12 sediment cores recovered from the Arkhangelsky Ridge in the SE Black Sea. Stacking of the individual partly fragmented records was achieved by a detailed correlation using high‐resolution data records from X‐ray fluorescence scanning, Ca/Ti and K/Ti log‐ratios, as well as magnetic susceptibility. Age constraints are provided by a detailed composite oxygen isotope stratigraphy from three of the cores, correlated to U‐Th‐dated speleothem oxygen isotope records from Hungary and Turkey. The temporal resolution of the stacked paleomagnetic data records is 200 years. Practically, this data set is the first high‐resolution PSV record for SE Europe/SW Asia from marine isotope stage 6, comprising inclination, declination and relative paleointensity. Besides an easterly swing in declination at ∼159 ka and a pronounced intensity low together with low inclinations at ∼148 ka, both not reaching an excursional PSV index of 〉0.5, the obtained directional variations reflect only normal PSVs, with a PSV index of 〈0.3.
    Description: Key Points: Reconstructed geomagnetic field variation record between 180 and 130 ka from Black Sea sediments. First full‐vector paleosecular variation record from marine isotope stage 6 for Southeast Europe/Southwest Asia. Intensity maxima occur at 166.5 ka and at 141.0 ka.
    Description: Chinese Scholarship Council
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: 538.7 ; Black Sea ; geomagnetism ; magnetostratigraphy ; paleomagnetism ; paleosecular variation
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    Tackling the Challenge of Extracting Microplastics from Soils: A Protocol to Purify Soil Samples for Spectroscopic Analysis (2021)
    Details
    Publication Date: 2021-07-21
    Description: Microplastic pollution in soils is an emerging topic in the scientific community, with researchers striving to determine the occurrence and the impact of microplastics on soil health, ecology, and functionality. However, information on the microplastic contamination of soils is limited because of a lack of suitable analytical methods. Because micro‐Fourier‐transform infrared spectroscopy (µ‐FTIR), next to Raman spectroscopy, is one of the few methods that allows the determination of the number, polymer type, shape, and size of microplastic particles, the present study addresses the challenge of purifying soil samples sufficiently to allow a subsequent µ‐FTIR analysis. A combination of freeze‐drying, sieving, density separation, and a sequential enzymatic‐oxidative digestion protocol enables removal of the mineral mass (〉99.9% dry wt) and an average reduction of 77% dry weight of the remaining organic fraction. In addition to visual integrity, attenuated total reflectance FTIR, gel permeation chromatography, and differential scanning calorimetry showed that polyamide, polyethylene, polyethylene terephthalate, and polyvinyl chloride in the size range of 100 to 400 µm were not affected by the approach. However, biodegradable polylactic acid showed visible signs of degradation and reduced molecular weight distribution after protease treatment. Nevertheless, the presented purification protocol is a reliable and robust method to purify relatively large soil samples of approximately 250 g dry weight for spectroscopic analysis in microplastic research and has been shown to recover various microplastic fibers and fragments down to a size of 10 µm from natural soil samples. Environ Toxicol Chem 2021;00:1–14. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Description: A novel purification sequence for natural soil samples undergoing microplastic analysis. image
    Description: Ministry for Environment, Climate Protection and Energy of Baden Württemberg
    Description: German Federal Ministry of Education and Research (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: German Research Foundation (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: 363.7 ; Microplastics ; Soil contamination ; Analytical chemistry ; Purification protocol ; Enzymatic‐oxidative digestion ; µ‐FTIR
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    Late Pleistocene to Holocene vegetation and climate changes in northwestern Chukotka (Far East Russia) deduced from lakes Ilirney and Rauchuagytgyn pollen records (2021)
    Details
    Publication Date: 2021-07-21
    Description: This paper presents two new pollen records and quantitative climate reconstructions from northern Chukotka documenting environmental changes over the last 27.9 ka. Open tundra‐ and steppe‐like habitats dominated between 27.9 and 18.7 cal. ka BP. Betula and Alnus shrubs might have grown in sheltered microhabitats but disappeared after 18.7 cal. ka BP. Although the climate was rather harsh, local herb‐dominated communities supported herbivores as is evident by the presence of coprophilous spores in the sediments. The increase in Salix and Cyperaceae ~16.1 cal. ka BP suggests climate amelioration. Shrub Betula appeared ~15.9 cal. ka BP, and became dominant after ~15.52 cal. ka BP, whilst typical steppe communities drastically reduced. Very high presence of Botryococcus in the Lateglacial sediments reflects widespread shallow habitats, probably due to lake level increase. Shrub Alnus became common after ~13 cal. ka BP reflecting further climate amelioration. Simultaneously, herb communities gradually decreased in the vegetation reaching a minimum ~11.8 cal. ka BP. A gradual decrease of algae remains suggests a reduction of shallow‐water habitats. Shrubby and graminoid tundra was dominant ~11.8–11.1 cal. ka BP, later Salix stands significantly decreased. The forest‐tundra ecotone established in the Early Holocene, shortly after 11.1 cal. ka BP. Low contents of green algae in the Early Holocene sediments likely reflect deeper aquatic conditions. The most favourable climate conditions were between ~10.6 and 7 cal. ka BP. Vegetation became similar to the modern after ~7 cal. ka BP but Pinus pumila came to the Ilirney area at about 1.2 cal. ka BP. It is important to emphasize that the study area provided refugia for Betula and Alnus during MIS 2. It is also notable that our records do not reflect evidence of Younger Dryas cooling, which is inconsistent with some regional environmental records but in good accordance with some others.
    Description: European Research Council
    Keywords: 561 ; arctic Chukotka ; Late Pleistocene ; Holocene ; lacustrine sediments ; pollen stratigraphy ; climate change
    Type: article
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    Bayesian Hierarchical Modeling of Nitrate Concentration in a Forest Stream Affected by Large‐Scale Forest Dieback (2021)
    Details
    Publication Date: 2021-07-21
    Description: The ecosystem function of vegetation to attenuate export of nutrients is of substantial importance for securing water quality. This ecosystem function is at risk of deterioration due to an increasing risk of large‐scale forest dieback under climate change. The present study explores the response of the nitrogen (N) cycle of a forest catchment in the Bavarian Forest National Park, Germany, in the face of a severe bark beetle (Ips typographus Linnaeus) outbreak and resulting large‐scale forest dieback using top‐down statistical‐mechanistic modeling. Outbreaks of bark beetle killed the dominant tree species Norway spruce (Picea abies (L.) H.Karst.) in stands accounting for 55% of the catchment area. A Bayesian hierarchical model that predicts daily stream NO3 concentration (C) over three decades with discharge (Q) and temperature (T) (C‐Q‐T relationship) outperformed alternative statistical models. A catchment model was subsequently developed to explain the C‐Q‐T relationship in top‐down fashion. Annually varying parameter estimates provide mechanistic interpretations of the catchment processes. Release of NO3 from decaying litter after the dieback was tracked by an increase of the nutrient input parameter cs0. The slope of C‐T relation was near zero during this period, suggesting that the nutrient release was beyond the regulating capacity of the vegetation and soils. Within a decade after the dieback, the released N was flushed out and nutrient retention capacity was restored with the regrowth of the vegetation.
    Description: Key Points: Pulse of nitrate export from a forest catchment in response to bark beetle infestation followed by recovery of nutrient retention capacity Top‐down, data‐driven Bayesian hierarchical model assists mechanistic interpretation of hydrochemical processes Concentration‐discharge‐temperature relationship is shaped by spatial heterogeneity of nutrient and seasonality of biogeochemical reactions
    Keywords: 551.48 ; Bark beetle ; Bayesian hierarchical modeling ; forest dieback ; nitrate
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    Macrofauna as a major driver of bentho‐pelagic exchange in the southern North Sea (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-06-22
    Description: The contribution of sediments to nutrient cycling of the coastal North Sea is strongly controlled by the intensity of fluxes across the sediment water interface. Pore‐water advection is one major exchange mechanism that is well described by models, as it is determined by physical parameters. In contrast, biotransport (i.e., bioirrigation, bioturbation) as the other major transport mechanism is much more complex. Observational data reflecting biotransport, from the German Bight for example, is scarce. We sampled the major sediment provinces of the German Bight repeatedly over the years from 2013 to 2019. By employing ex situ whole core incubations, we established the seasonal and spatial variability of macrofauna‐sustained benthic fluxes of oxygen and nutrients. A multivariate, partial least squares analysis identified faunal activity, in specifically bioturbation and bioirrigation, alongside temperature, as the most important drivers of oxygen and nutrient fluxes. Their combined effect explained 63% of the observed variability in oxygen fluxes, and 36–48% of variability in nutrient fluxes. Additional 10% of the observed variability of fluxes were explained by sediment type and the availability of plankton biomass. Based on our extrapolation by sediment provinces, we conclude that pore‐water advection and macrofaunal activity contributed equally to the total benthic oxygen uptake in the German Bight.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: 551 ; southern North Sea ; coastal sediments ; macrofauna ; bioturbation ; bioirrigation ; organic matter turnover
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    Numerically stable form factor of any polygon and polyhedron (2021)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-06-05
    Description: Coordinate‐free expressions for the form factors of arbitrary polygons and polyhedra are derived using the divergence theorem and Stokes's theorem. Apparent singularities, all removable, are discussed in detail. Cancellation near the singularities causes a loss of precision that can be avoided by using series expansions. An important application domain is small‐angle scattering by nanocrystals.
    Description: Coordinate‐free expressions for the form factors of arbitrary polygons and polyhedra are derived using the divergence theorem and Stokes's theorem. Series expansions are used to ensure numeric precision close to apparent singularities. image
    Keywords: 548 ; form factors ; polyhedra ; Fourier shape transform
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    Modeling of Planetary Wave Influences on the Pre‐reversal Enhancement of the Equatorial F Region Vertical Plasma Drift (2021)
    Details
    Publication Date: 2021-07-21
    Description: Temporal and longitudinal variations of the pre‐reversal enhancement (PRE) in the equatorial F region vertical plasma drift are examined based on idealized simulations by the thermosphere‐ionosphere‐electrodynamics general circulation model performed under geomagnetically quiet (Kp = 1) and high solar‐flux (F10.7 = 200) conditions. The model takes into account forcing by large‐scale waves from the middle and lower atmosphere, which leads to day‐to‐day variations of PRE. Simulations are performed under different wave forcing in order to separate contributions of various types of waves. It is shown that the simulated day‐to‐day variability of the PRE intensity is predominantly due to forcing by waves with periods less than 2 days, that is, tides and their modulation. Planetary‐wave forcing (periods of 2–20 days) makes contributions to periodic oscillations in the PRE intensity. Especially, the westward‐propagating quasi‐6‐day wave (Q6DW) with zonal wavenumber 1 is found to be an important source of ∼6‐day oscillations of PRE. Not only the Q6DW from below but also the Q6DW generated within the thermosphere, as well as the secondary waves due to the nonlinear interaction between the Q6DW and migrating tides, is at play. The zonal wavenumber 1 nature of the ∼6‐day oscillations could contribute to longitudinal differences in the appearance of equatorial spread F and plasma bubbles, which are strongly controlled by PRE.
    Description: Key Points: Quiet‐time day‐to‐day and longitudinal variability of the pre‐reversal enhancement (PRE) in the equatorial vertical plasma drift is examined. Planetary‐wave influences on PRE are evaluated for the first time using global simulations. Quasi‐6‐day wave can lead to ∼6‐day oscillations in the PRE intensity with zonal wavenumber 1.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: 538.7 ; equatorial ionosphere ; F‐region dynamo ; planetary wave ; pre‐reversal enhancement ; quasi‐6‐day wave ; vertical plasma drift
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    Multistatic Specular Meteor Radar Network in Peru: System Description and Initial Results (2021)
    Details
    Publication Date: 2021-07-21
    Description: The mesosphere and lower thermosphere (MLT) region is dominated globally by dynamics at various scales: planetary waves, tides, gravity waves, and stratified turbulence. The latter two can coexist and be significant at horizontal scales less than 500 km, scales that are difficult to measure. This study presents a recently deployed multistatic specular meteor radar system, SIMONe Peru, which can be used to observe these scales. The radars are positioned at and around the Jicamarca Radio Observatory, which is located at the magnetic equator. Besides presenting preliminary results of typically reported large‐scale features, like the dominant diurnal tide at low latitudes, we show results on selected days of spatially and temporally resolved winds obtained with two methods based on: (a) estimation of mean wind and their gradients (gradient method), and (b) an inverse theory with Tikhonov regularization (regularized wind field inversion method). The gradient method allows improved MLT vertical velocities and, for the first time, low‐latitude wind field parameters such as horizontal divergence and relative vorticity. The regularized wind field inversion method allows the estimation of spatial structure within the observed area and has the potential to outperform the gradient method, in particular when more detections are available or when fine adaptive tuning of the regularization factor is done. SIMONe Peru adds important information at low latitudes to currently scarce MLT continuous observing capabilities. Results contribute to studies of the MLT dynamics at different scales inherently connected to lower atmospheric forcing and E‐region dynamo related ionospheric variability.
    Description: Plain Language Summary: The mesosphere and lower thermosphere (MLT) region is dominated by neutral wind dynamics with structure scales ranging from a few thousands of kilometers down to a few kilometers. In this work, we present a new state‐of‐the‐art ground‐based radar system using multistatic meteor scattering that allows tomographic studies of MLT wind dynamics at scales not possible before. Given the location of the radar network at the magnetic equator, its focus is on wind dynamics peculiar to equatorial latitudes. Two methods for estimating the mesospheric neutral wind field are used. One takes into account wind gradients in addition to mean wind (gradient method). The other estimates a spatially resolved wind vector field and uses an additional mathematical constraint that produces smooth wind field solutions (regularized wind field inversion method). Using the gradient method, the vertical wind estimate is improved. For the first time at MLT equatorial latitudes, parameters familiar to meteorologists, such as horizontal divergence and relative vorticity are obtained. Measurements from this new system have the potential to contribute to coupling studies of the atmosphere and the ionosphere at low latitudes.
    Description: Key Points: Measurements of horizontal wind gradients at low‐latitude mesosphere and lower thermosphere altitudes. These gradients of the horizontal winds show strong temporal and altitude variability that are not observed at high latitudes. Improved vertical winds are obtained using a gradient wind field method inherently free from horizontal divergence contamination.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: NSF, Directorate for Geosciences (GEO) http://dx.doi.org/10.13039/100000085
    Keywords: 551.5 ; low latitude mesosphere ; MLT dynamics ; MLT horizontal divergence ; MLT vorticity ; multistatic radar observations ; vertical velocity
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    Cable reverberations during wireline distributed acoustic sensing measurements: their nature and methods for elimination (2021)
    Details
    Publication Date: 2021-07-21
    Description: The application of distributed acoustic sensing in borehole measurements allows for the use of fibre optic cables to measure strain. This is more efficient in terms of time and costs compared with the deploying of conventional borehole seismometers. Nevertheless, one known drawback for temporary deployment is represented by the freely hanging wireline cable slapping and ringing inside the casing, which introduces additional coherent coupling noise to the data. The present study proposes an explanation for the mechanism of noise generation and draws an analogy with similar wave propagation processes and phenomena, such as ghost waves in marine seismics. This observation allows to derive a ringing noise filter function, to study its behaviour and to consider known effects of the gauge length filter. After examining existing methods aimed at eliminating ringing noise and results of their application, we propose a two‐step approach: (1) developing a denoising method based on a matching pursuit decomposition with Gabor atoms and (2) subtracting the noise model for imaging improvement. The matching pursuit method focuses on decomposing the original input signal into a weighted sum of Gabor functions. Analysing Gabor atoms properties for frequency, amplitude and position in time provides the opportunity to distinguish parts of the original signal denoting noise caused by the vibrating cable. The matching pursuit decomposition applied to the distributed acoustic sensing‐vertical seismic profiling data at the geothermal test site Groß Schönebeck provides a versatile processing instrument for noise suppression.
    Description: German Federal Ministry of Economic Affairs and Energy
    Keywords: 550 ; Borehole geophysics ; Distributed acoustic sensing ; Noise ; Signal processing ; Vertical seismic profiling
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    Segment‐Scale Seismicity of the Ultraslow Spreading Knipovich Ridge (2021)
    Details
    Publication Date: 2021-07-21
    Description: Ultraslow spreading ridges form the slowest divergent plate boundaries and exhibit distinct spreading processes in volcanically active magmatic sections and intervening amagmatic sections. Local seismicity studies of ultraslow spreading ridges until now cover only parts of segments and give insight into spreading processes at confined locations. Here, we present a microseismicity data set that allows to study spreading processes on the scale of entire segments. Our network of 26 ocean bottom seismometers covered around 160 km along axis of the ultraslow spreading Knipovich Ridge in the Greenland Sea and recorded earthquakes for a period of about 1 year. We find seismicity varying distinctly along‐axis. The maximum earthquake depths shallow over distances of 70 km toward the Logachev volcanic center. Here, swarm activity occurs in an otherwise aseismic zone. Melts may thus be guided along the subparallel topography of the lithosphere‐asthenosphere boundary toward major volcanic centers explaining the uneven along‐axis melt distribution typical for ultraslow ridges. Absence of shallow seismicity in the upper 8 km of the lithosphere with a band of deep seismicity underneath offsets presumably melt‐poor regions from magma richer sections. Aseismic deformation in these regions may indicate weakening of mantle rocks by alteration. We do not find obvious indications for major detachment faulting that characterizes magma‐poor spreading at some ultraslow spreading segments. The highly oblique spreading of Knipovich Ridge may be the reason for a fine‐scale segmentation of the seismic activity with zones of weak seismicity possibly indicating transform motion on short obliquely oriented faults.
    Description: Plain Language Summary: At mid‐ocean spreading ridges, tectonic plates drift apart and new seafloor is built by upwelling magma. The slowest spreading ridges do not receive enough magma to build new seafloor along the entire ridge. Rather, they show widely spaced volcanic centers with magma‐poor areas in‐between. The study of small earthquakes with seismometers placed on the seafloor has greatly helped to understand how new seafloor forms. Since such studies require substantial logistic effort, only confined ridge sections have been studied and spreading processes operating at segment‐scale remain poorly understood. In this study, we present for the first time observations of earthquakes covering several segments and one major volcanic center along the Knipovich Ridge in the Greenland Sea. Underneath the volcano, earthquake swarms and a gap in seismicity indicate recent magmatic activity. The maximum depth of earthquakes marks the thickness of the mechanically strong lithosphere. It shallows over 70 km toward the volcano such that melts can be channeled over large distances to the prominent volcanoes. Magma‐poor regions have deep earthquakes but do not show earthquake activity in the upper 8 km. We suppose that water reacts with the mantle rocks that become too weak to break in earthquakes.
    Description: Key Points: Magma‐poor sections are distinguished from magma‐rich sections by deeper hypocenters and an absence of shallow seismicity. Shallowing maximum earthquake depths over distances of 70 km suggest along‐axis melt focusing toward major volcanic centers. Major detachment faults on the highly oblique spreading Knipovich Ridge were not obvious in the observed seismicity.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: Helmholtz Excellence Network POSY at the Alfred Wegener Institute
    Description: Ministry of Science and Higher Education of Poland
    Keywords: 551 ; amagmatic ; Knipovich Ridge ; mid‐ocean ridge ; segmentation ; seismicity ; ultraslow spreading
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    A cold pool perturbation scheme to improve convective initiation in convection‐permitting models (2021)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2021-07-20
    Description: Cold pools originate from evaporation in precipitating downdraughts and spread as density currents at the surface. Vertical motion at the leading edge of the cold pool is an important trigger for new convective cells in organised convective storms. However, these motions are poorly resolved at the grid lengths of a kilometre or more used in convection‐permitting models. Consequently, the simulated gust fronts do not trigger enough new convection, leading to precipitation deficits and a lack of convective organization. To address these deficits, we introduce a cold pool perturbation (CPP) scheme that strengthens vertical velocity at the simulated cold pool gust fronts. This is achieved by relaxing the vertical velocity in the gust front region towards a target value derived from similarity theory. Applying the CPP scheme for simulations of a highly convective 10‐day period, we find increased precipitation amplitudes during the afternoon. There is also evidence for improvements in the location of precipitation and for stronger organization of convection, although substantial errors remain. The cold pools themselves become more frequent, larger and more intense. An additional potentially beneficial influence was found for convective initiation at sea breeze fronts.
    Description: We develop a cold pool perturbation scheme which strengthens the too weak vertical velocities at cold pool gust fronts in convection‐permitting models. In so doing, cold‐pool‐driven convective initiation is enhanced and simulated precipitation improved.
    Keywords: 551.5 ; cold pools ; convective organization ; deep convection ; density currents ; gust fronts
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    Influence of Volatiles on Mass Wasting Processes on Vesta and Ceres (2021)
    Details
    Publication Date: 2021-07-21
    Description: We have analyzed mass wasting features, their distribution and deposit geometry on the two largest main asteroid belt objects—protoplanet Vesta and dwarf planet Ceres—and compared their geomorphology and mobility. Both asteroids have similar surface accelerations, but different surface compositions. Based on our observations and previous studies, we categorized three distinct morphological mass wasting classes: slumps, slides, and flow‐like movements. We conclude that Ceres has abundant features of flow‐like mass movements. Further, sliding and flow‐like characteristics are identified in craters within mid‐latitudes which supports the possibility of the presence of water ice in the near subsurface of Ceres. Vesta predominantly shows characteristics of dry granular‐like slide features which are distributed homogenously across the surface. By plotting the ratio between fall height (H) and run‐out length (L) (effective coefficient of friction, H/L) against the run‐out length and spreading width (W), we demonstrate that deposits on Vesta terminate on shorter distances, whereas on Ceres they travel longer distances. The deposit geometry and the similar surface gravity on both asteroids suggest that the material composition and volatile component have a significant effect on deposit emplacement. However, both bodies’ mass movements have similar effective coefficients of friction, even though Vesta's regolith is comparatively dry, whereas Ceres is rich in water ice. This leads to the conclusion that volatile content alone cannot be responsible for low effective coefficients of friction, and that more than one geological process is needed to explain the mass motion behavior and morphology.
    Description: Plain Language Summary: Landslides are one of the most studied geological events on planetary bodies. Many scientists have contributed to a diverse database of knowledge with the aim to better understand these processes. They have been observed for various environmental conditions and are affected by gravity and the physical and chemical composition of the hosting body. However, it is challenging to delineate which specific type or morphology of landslide is sensitive to which parameter. On airless asteroids Vesta and Ceres, landslides have been well preserved, allowing for in‐depth analysis using remote sensing data. Interestingly, Vesta and Ceres’ substantially different surface compositions have a major effect on landslides, despite their similar gravity. In our study, we have examined and updated the landslide inventory on both bodies, and performed an analysis of deposit mobility which will further enhance our understanding related to the material conditions, their mobility, and surface evolution.
    Description: Key Points: We classified and estimated the H/L of mass movements to investigate the mechanisms of deposition on Vesta and Ceres Vesta has dry, granular‐like slides as dominant mass wasting feature, whereas Ceres has abundant features of flow‐like mass movements The mass wasting deposit mobility is influenced by the material composition and volatile content on Vesta and Ceres
    Keywords: 523 ; Ceres ; friction‐coefficient ; mass wasting ; Vesta
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    Räumliche ingenieurgeologische Modellierung im Stadtgebiet von Göttingen (2021)
    Details
    Publication Date: 2021-05-27
    Description: In städtischen Räumen erhobene geologische, hydrogeologische und ingenieurgeologische Punkt- und Flächendaten werden meist dezentral verwaltet. Erst durch das Überführen der unterschiedlichen Punkt- und Flächendaten in ein Raummodell wird eine integrierende Auswertung möglich. Ein solches Raummodell des städtischen Untergrundes kann als Datenbasis für umfassende geowissenschaftliche Planungsunterlagen dienen, die ein Themenspektrum von der Baugrunderschließung, Grundwasser- und Altlastenerkundung bis hin zur flachen Geothermie abdecken. In einem Kooperationsprojekt zwischen dem Geowissenschaftlichen Zentrum der Universität Göttingen (GZG) und dem Landesamt für Bergbau, Energie und Geologie (LBEG) werden am Beispiel des mitteltiefen Untergrundes im Göttinger Stadtgebiet neue Methoden zum Aufbau geologisch/ingenieurgeologischer Raummodelle untersucht. Die bisher entwickelten Konzepte umfassen das einheitliche Aufbereiten von Punkt- und Flächendaten sowie die Definition ingenieurgeologischer Modellierungseinheiten. Aufbereitete Daten und 2D-Schnittdarstellungen dieser Modellierungseinheiten wurden in einem Pilotgebiet mit der Software Gocad in das eigentliche geologische Raummodell und modelltechnisch beschreibbare Basisflächen der Modellierungseinheiten überführt.
    Description: conference
    Keywords: FID-GEO-DE-7
    Language: German
    Type: conferencePaper
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    Teeth of Past and Present Elephants: Microstructure and Composition of Enamel in Fossilized Proboscidean Molars and Implications for Diagenesis (2021)
    Details
    Publication Date: 2021-07-21
    Description: Enamel as hardest biological tissue remains unaltered for millions of years and is therefore an excellent archive for studies on paleodiet, paleoecology, paleoclimate, paleoenvironment, biomechanical, and evolutionary studies. However, diagenetic alterations can influence such interpretations and therefore we analyzed the microstructure and composition (elemental and stable isotopic) of fossil and extant proboscidean teeth to study the extent of diagenesis in them. We report for the first time on the enamel microstructure data of the Indian elephantiformes Anancus, Stegodon, Elephas, and Palaeoloxodon besides analyzing Gomphotherium and Deinotherium from new formations. Furthermore, we compare their microstructure with those of the primitive African taxa of Moeritherium and Palaeomastodon. Our results from depth‐related elemental composition and oxygen isotope ratios of enamel phosphate and carbonate indicate no or only negligible modification. There is also a lack of age‐dependency of these minor alterations within the fossils collected from Siwaliks of the Himalayan Foreland Basin. Overall, our study indicates that diagenesis has not played any significant role on the samples studied here and are therefore well suited for chemical and paleontological studies and proxy for paleoclimate and paleoenvironment reconstruction.
    Description: Key Points: Enamel of fossil elephants is well‐preserved from diagenesis. Electron microscopy, X‐ray diffraction, isotope analysis and elemental analysis give the composition and ultrastructure of enamel.
    Description: Deutscher Akademischer Austauschdienst (DAAD) http://dx.doi.org/10.13039/501100001655
    Description: Department of Science and Technology, Ministry of Science and Technology, India (DST) http://dx.doi.org/10.13039/501100001409
    Description: Ministry of Earth Sciences (MoES) http://dx.doi.org/10.13039/501100001851
    Description: DST, Science and Engineering Research Board (SERB) http://dx.doi.org/10.13039/501100001843
    Keywords: 560.4 ; diagenesis ; enamel ; microstructure ; oxygen isotopes ; Proboscidean ; teeth
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    Mega‐scale glacial lineations formed by ice shelf grounding in the Canadian Beaufort Sea during multiple glaciations (2021)
    Details
    Publication Date: 2021-07-21
    Description: Mega‐scale glacial lineations formed by the raking of ice shelves across the seafloor have been reported from multiple polar regions. Here, we present the first evidence of continental slope situated buried lineations in the southern Canadian Beaufort Sea in present‐day water depths of 220 to 800 m. Three separate surfaces with lineations are defined at sub‐seafloor depths of 40 m to 390 m. All lineations are mostly parallel to the general trend of slope contours. The uppermost surface is recognized over a distance of 56 km. In water depths 〉 500 m the lineations are parallel to each other at a consistent direction (43°–44°). The second lineated surface is a regionally occurring erosional unconformity. This event has two sub‐sets of lineations: mid‐slope situated lineations oriented at 42°–48°, and lineations closer to the continental shelf break at 55°–59°. The third lineated surface is an unconformable horizon buried up to 390 m below seafloor with lineaments oriented between 30° and 55°. All three sets of lineations are interpreted to have been produced by ice‐ploughing on the paleo‐seafloor through the grounding of an ice shelf. Our observations are similar to those documented along the slope off northern Alaska, Chukchi Rise, and Lomonosov Ridge. Collectively, these observations support the concept of an extensive ice shelf across the Arctic Ocean that grounded locally along its margins during multiple glaciations, including during the penultimate (or an earlier) glaciation. The youngest set of lineations indicates ice movement to the southwest with a suggested source in Amundsen Gulf and/or M'Clure Strait. Tentative age considerations for these youngest lineations indicate the first evidence for an analogous extensive ice shelf configuration for the Last Glacial Maximum.
    Description: We present the first evidence of continental slope situated buried lineations in the southern Canadian Beaufort Sea in present‐day water depths of 220 to 800 m. Three stratigraphically separate surfaces with lineations have been defined from three‐dimensional seismic data. All three sets of lineations are interpreted to have originated from interactions of an ice‐shelf that locally grounded with soft sediments at the paleo‐seafloor.
    Description: Ministry of Oceans and Fisheries, Korea http://dx.doi.org/10.13039/501100003566
    Description: Geological Survey of Canada‐Pacific
    Description: British Petroleum Canada
    Description: Imperial Oil Resources Canada Ltd
    Keywords: 551.3 ; 3D seismic data ; Canadian Beaufort Sea ; ice shelf grounding ; Last Glacial Maximum ; mega‐scale glacial lineations
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    Wechselbeziehungen zwischen Mensch und Umwelt – Vergangenheit, Gegenwart und Zukunft im Braunschweiger Land und seinem Umfeld (2021)
    Details
    Publication Date: 2021-06-10
    Description: Die einzelnen Arbeiten in diesem Heft resultieren aus den Beiträgen zu einem wissenschaftlichen Workshop, der am 14. und 15. September 2017 in Schöningen und Helmstedt stattgefunden hat. Er stand unter dem Thema „Wechselbeziehungen zwischen Mensch und Umwelt – Vergangenheit, Gegenwart und Zukunft im Braunschweiger Land und seinem Umfeld“. Die einzelnen Beiträge diskutieren Forschungsergebnisse und -potentiale aus den Themengebieten Geologie, Archäologie und Mensch und Natur. Es wird eine große Vielfalt von spannenden Themen vorgestellt, zu denen aktuell im Braunschweiger Land und seiner unmittelbaren Umgebung geforscht wird, und aus denen sich weitergehende Perspektiven entwickeln lassen.
    Description: conference
    Keywords: 508.43 ; 554.3 ; Braunschweiger Land ; Harz ; Geologie ; Archäologie ; Mensch und Natur ; FID-GEO-DE-7
    Language: German
    Type: anthology_first
    Format: 180
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    Ionospheric Signatures of Secondary Waves From Quasi‐6‐Day Wave and Tide Interactions (2021)
    Details
    Publication Date: 2021-07-21
    Description: A sudden stratospheric waring occurred in the southern hemisphere during September 2019, accompanied by an exceptionally strong quasi‐6‐day wave (Q6DW). We examine the ionospheric response using global total electron content (TEC) maps, with a focus on the short‐period variability (5–48 h). A Fourier analysis of the TEC data reveals ionospheric variations associated with the secondary waves due to the non‐linear interaction between the Q6DW and atmospheric tides. The largest signatures among them are related to the ∼29‐h standing oscillation, which is attributable to the Q6DW interaction with the migrating diurnal tide, with the maximum amplitude ∼8% of the zonal mean. Also detected are the signatures associated with the westward‐propagating ∼13‐h oscillation with the zonal wavenumber 1 (∼4%) and westward‐propagating ∼11‐h oscillation with the zonal wavenumber 3 (∼3%), both of which can be attributed to the Q6DW interaction with the migrating semidiurnal tide. The signatures related to the Q6DW interaction with the migrating terdiurnal tide and some non‐migrating tides are also observed. This is the first time that secondary wave signatures of the Q6DW‐tidal interaction are identified in ionospheric observations with predicted zonal wavenumbers and periods. The oscillations are symmetric about the magnetic equator with amplitude peaks at ±20° magnetic latitudes, suggesting that the oscillations are generated by the modulation of the equatorial plasma fountain.
    Description: Key Points: Spectrum analysis is performed on total electron content during the quasi‐6‐day wave event in September 2019. Signatures of secondary waves from the non‐linear interaction of the quasi‐6‐day wave with tides are detected. The wave signatures result from the modulation of the equatorial plasma fountain.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: MEXT, Japan Society for the Promotion of Science (JSPS) http://dx.doi.org/10.13039/501100001691
    Description: European Space Agency (ESA) http://dx.doi.org/10.13039/501100000844
    Keywords: 538.7 ; atmospheric tides ; non‐linear interaction ; quasi‐6‐day wave ; secondary waves ; sudden stratospheric warming ; total electron content
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    Intratest Variations in Trace Element Composition of Amphistegina lessonii Using Femtosecond‐Laser Ablation‐ICP‐Mass Spectrometry: A Field Study From Akajima, Okinawa Prefecture, Japan (2021)
    Details
    Publication Date: 2021-07-21
    Description: Amphistegina are common larger benthic foraminifer in coral reefs, with a nearly circumtropical distribution, and are major contributors to the CaCO3 budget of shallow marine environments. The family Amphisteginidae is dominant in Cenozoic carbonates. However, its potential as a proxy for paleoclimate reconstruction has not been completely explored. The intratest variability in trace elements of Amphistegina lessonii has been investigated using femtosecond‐laser ablation‐inductively coupled plasma‐mass spectrometry (fs‐LA‐ICP‐MS). We collected and analyzed adult specimens of A. lessonii in September 2003, November 2003, January 2004, and March 2004, from ∼2 m water depth in the coral reefs of Akajima, Okinawa, Japan. Tests of A. lessonii from these four collections were analyzed for Mg/Ca of the septa to observe Test Size‐Lifespan relationships. The lifespan of a specimen of A. lessonii of 1,200 µm in diameter is estimated at ∼3 and ∼2 months for specimens 900 µm in size. Over the estimated lifespans, Mg/Ca of individual specimens of A. lessonii is highly variable and displays co‐variation with temperature and tidal heights. Future projects may apply and further test this approach for the reconstruction of the tropical shallow marine paleoenvironments.
    Description: Plain Language Summary: Larger Benthic Foraminifera (LBF) have slow growth rates and can be used as a proxy to reconstruct seasonal variations in temperature. Amphistegina, a common genus of LBF found within the Cenozoic era including the past 55 million years, was sampled across four seasons from a modern coral reef of Okinawa, Japan. The trace element concentrations in nine specimens of A. lessonii were measured using femtosecond LA‐ICP‐MS. The intratest variation in Mg/Ca covaried with tidal heights and seawater temperature, assuming the ages of the specimens to be 2–3 months. We provide a temperature calibration equation for A. lessonii for reconstructing paleotemperatures of shallow marine environments of the Cenozoic.
    Description: Key Points: Specimens of Amphistegina lessonii sampled across 4 months from Akajima are used for calibration for Mg/Ca temperature using femtosecond‐laser ablation‐inductively coupled plasma‐mass spectrometry. The Mg/Ca along the septa of A. lessonii covaries with seawater temperature and tidal heights while Na/Ca and Sr/Ca show no correlation. Intratest variations in Mg/Ca of A. lessonii are affected by light intensity attenuation by sediment re‐suspension caused by tidal currents.
    Keywords: 551.9 ; Amphistegina lessonii ; fs‐LA‐ICP‐MS ; sea‐surface temperature ; tidal heights ; trace elements
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    Zircon and Melt Extraction From a Long‐Lived and Vertically Extensive Magma System Underneath Ilopango Caldera (El Salvador) (2021)
    Details
    Publication Date: 2021-07-21
    Description: The Tierra Blanca (TB) eruptive suite comprises the last four major eruptions of Ilopango caldera in El Salvador (≤45 ka), including the youngest Tierra Blanca Joven eruption (TBJ; ∼106 km3): the most voluminous event during the Holocene in Central America. Despite the protracted and productive history of explosive silicic eruptions at Ilopango caldera, many aspects regarding the longevity and the prevailing physicochemical conditions of the underlying magmatic system remain unknown. Zircon 238U‐230Th geochronology of the TB suite (TBJ, TB2, TB3, and TB4) reveals a continuous and overlapping crystallization history among individual eruptions, suggesting persistent melt presence in thermally and compositionally distinct magma reservoirs over the last ca. 80 kyr. The longevity of zircon is in contrast to previously determined crystallization timescales of 〈10 kyr for major mineral phases in TBJ. This dichotomy is explained by a process of rhyolitic melt segregation from a crystal‐rich refractory residue that incorporates zircon, whereas a new generation of major mineral phases crystallized shortly before eruption. Ti‐in‐zircon temperatures and amphibole geothermobarometry suggest that rhyolitic melt was extracted from different storage zones of the magma reservoir as indicated by distinct but synchronous thermochemical zircon histories among the TB suite eruptions. Zircon from TBJ and TB2 suggests magma differentiation within deeper and hotter parts of the reservoir, whereas zircon from TB3 and TB4 instead hints at crystallization in comparatively shallower and cooler domains. The assembly of the voluminous TBJ magma reservoir was also likely enhanced by cannibalization of hydrothermally altered components as suggested by low‐δ18O values in zircon (+4.5 ± 0.3‰).
    Description: Plain Language Summary: The collapse of a volcano edifice into its shallow magma chamber can produce one of the most dangerous single events in nature, known as a caldera‐forming eruption. The TBJ eruption in El Salvador is of this kind and occurred around 1,500 years ago, having a profound impact on Maya societies. Because of this, it is crucial to understand the inner workings of caldera‐forming eruptions to assess volcanic risks and their mitigation. Beneath Ilopango caldera, the micrometer‐sized radioisotopically datable mineral zircon grew within different storage levels of a silica‐rich magma reservoir suggesting continuous melt presence for up to ca. 80,000 years prior to eruption. The time information given by zircon contrasts with that extracted from other, more abundant minerals from the same rocks (〈10,000 years). We explain this time difference between coexisting minerals by the ability of melt to carry along small zircon crystals, whereas coeval, larger, and more abundant minerals are left behind in the partially solidified portion of the magma reservoir. Once the segregated melt coalesced in a shallower and dominantly liquid magma chamber, major minerals resumed crystallization shortly before eruption. In addition, this new magma incorporated parts of older magmatic rocks from preceding volcanic cycles, thus generating even larger magma volumes.
    Description: Key Points: U‐Th zircon ages for the last four explosive eruptions of Ilopango caldera reveal a long‐lived magma reservoir (〉80 kyr). Contrasting residence times for major minerals and zircon suggest extraction of zircon along with evolved melt from crystal residue. Melt extraction from vertically extensive, thermally zoned magma reservoir.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: 549 ; 551.701 ; Central America ; Geochemistry ; Oxygen isotopes ; SIMS ; U‐series ; Zircon
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    Toward Constraining Mars' Thermal Evolution Using Machine Learning (2021)
    Details
    Publication Date: 2021-07-21
    Description: The thermal and convective evolution of terrestrial planets like Mars is governed by a number of initial conditions and parameters, which are poorly constrained. We use Mixture Density Networks (MDN) to invert various sets of synthetic present‐day observables and infer five parameters: reference viscosity, activation energy and activation volume of the diffusion creep rheology, an enrichment factor for radiogenic elements in the crust, and initial mantle temperature. The data set comes from 6,130 two‐dimensional simulations of the thermal evolution of Mars' interior. We quantify the possibility of constraining a parameter using the log‐likelihood value from the MDN. Reference viscosity can be constrained to within 32% of its entire range (1019 − 1022 Pa s), when all the observables are available: core‐mantle‐boundary heat flux, surface heat flux, radial contraction, melt produced, and duration of volcanism. Furthermore, crustal enrichment factor (1–50) can be constrained, at best, to within 15%, and the activation energy (105 − 5 × 105 J mol−1) to within 80%. Initial mantle temperature can be constrained to within 39% of its range (1,600–1,800 K). Using the full present‐day temperature profile or parts of it as an observable tightens the constraints further. The activation volume (4 × 10−6 − 10 × 10−6 m3 mol−1) cannot be constrained. We also tested different levels of uncertainty in the observables and found that constraints on different parameters loosen differently, with initial temperature being the most sensitive. Finally, we present how a joint probability model for all parameters can be obtained from the MDN.
    Description: Plain Language Summary: The mantle of rocky planets like Mars behaves like a highly viscous fluid over geological time scales. Key parameters and initial conditions for the non‐linear partial differential equations governing mantle flow are poorly known. Machine Learning (ML) can help us avoid running several thousand computationally expensive fluid dynamic simulations each time to determine if an observable can constrain a parameter. Using an ML approach, we invert a set of synthetic observables such as present‐day surface heat flux, duration of volcanism and radial contraction to constrain important parameters controlling the long‐term evolution of the planet's interior, such as the reference mantle viscosity or the partitioning of radiogenic heat sources between mantle and crust. We demonstrate that by training a probabilistic ML algorithm on the data and applying it, we can quantify the constraints on parameters. This provides a high‐dimensional framework for analyzing inverse problems in geodynamics.
    Description: Key Points: Mixture Density Networks provide a probabilistic framework for inverting observables to infer parameters of Mars' interior evolution Reference viscosity, crustal enrichment in heat‐producing elements and initial mantle temperature can be well constrained Activation energy of diffusion creep can be weakly constrained; constraining activation volume requires new observational signatures
    Description: Helmholtz Einstein International Berlin Research School in Data Science (HEIBRiDS)
    Description: Berlin Institute for the Foundations of Learning and Data (BIFOLD)
    Description: Deutsche Forschungsgemeinschaft (DFG) Research Unit FOR 2440
    Keywords: 523 ; inverse problem ; mantle convection ; Mars ; mixture density networks
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    Moving Toward Standardized Toxicity Testing Procedures with Particulates by Dietary Exposure of Gammarids (2021)
    Details
    Publication Date: 2021-07-21
    Description: Ecotoxicological effect assessment of particulate materials and sparingly soluble substances is an emerging field. Current standard toxicity tests of aquatic organisms are based on soluble substances which are added to the aqueous phase. Although soluble substances distribute homogeneously, particles can form aggregates, resulting in inhomogeneous distribution and unpredictable exposure. Therefore, test scenarios need to be adapted to overcome these uncertainties. We present a dietary particle exposure tool for the toxicity testing of sparingly soluble substances or particles in combination with a standardizable food source for gammarids based on decomposition and consumption tablets (DECOTABs). Four food supplements in the DEOCOTAB formulation were compared to test their influence on the energy reserves of gammarids. Although feeding rate was constant for most supplements, mortality and energy reserves revealed clear differences. Tabs supplemented with algae‐based phyll or animal protein–based trout food best met all of the requirements. Fluorescent plastic microparticles (10–65 µm) were homogenously distributed and stable in the DECOTABs. Constant feeding was observed, and the number of ingested microparticles by Gammarus roeseli was quantified in relation to the consumed food. The developed method provides a realistic and methodologically reliable uptake from the oral pathway and allows the quantification of inner exposition via feeding rate, providing a promising tool for standardized dietary exposure scenarios with particles. Environ Toxicol Chem 2021;40:1463–1476. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Description: Bayerische Forschungsstiftung http://dx.doi.org/10.13039/501100002745
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: 571.95 ; Ingestion ; Particle ; Toxicity testing ; Oral pathway ; Feeding rate ; Dietary exposure
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    3D Local Earthquake Tomography of the Ecuadorian Margin in the Source Area of the 2016 Mw 7.8 Pedernales Earthquake (2021)
    Details
    Publication Date: 2021-07-21
    Description: Based on manually analyzed waveforms recorded by the permanent Ecuadorian network and our large aftershock deployment installed after the Pedernales earthquake, we derive three‐dimensional Vp and Vp/Vs structures and earthquake locations for central coastal Ecuador using local earthquake tomography. Images highlight the features in the subducting and overriding plates down to 35 km depth. Vp anomalies (∼4.5–7.5 km/s) show the roughness of the incoming oceanic crust (OC). Vp/Vs varies from ∼1.75 to ∼1.94, averaging a value of 1.82 consistent with terranes of oceanic nature. We identify a low Vp (∼5.5 km/s) region extending along strike, in the marine forearc. To the North, we relate this low Vp and Vp/Vs (〈1.80) region to a subducted seamount that might be part of the Carnegie Ridge (CR). To the South, the low Vp region is associated with high Vp/Vs (〉1.85) which we interpret as deeply fractured, probably hydrated OC caused by the CR being subducted. These features play an important role in controlling the seismic behavior of the margin. While subducted seamounts might contribute to the nucleation of intermediate megathrust earthquakes in the northern segment, the CR seems to be the main feature controlling the seismicity in the region by promoting creeping and slow slip events offshore that can be linked to the updip limit of large megathrust earthquakes in the northern segment and the absence of them in the southern region over the instrumental period.
    Description: Plain Language Summary: Using seismic data recorded by the permanent Ecuadorian network and the large emergency installation after the 2016 Pedernales earthquake, we obtained the seismic velocity structure together with precise earthquake locations for the coastal Ecuadorian margin. Our images highlight the heterogeneities of the subduction zone affected by seamounts and ridges comprising the oceanic crust. These features play an important role in controlling the seismic behavior of the margin. While seamounts can contribute to the occurrence of intermediate (M ∼ 7–7.5) megathrust earthquakes in the north, the Carnegie Ridge seems to be the main feature controlling the seismicity in the region by promoting creeping and slow slip events offshore that can be linked to the updip limit of large megathrust earthquakes in the northern segment and the absence of them in the southern region.
    Description: Key Points: 3D Vp and Vp/Vs models were calculated using local earthquake tomography in the region affected by the 2016 Pedernales, Ecuador earthquake Tomographic images highlight the heterogeneities of the margin affected by seamounts and ridges comprising the oceanic crust Carnegie Ridge seems the main feature controlling the seismic activity and the offshore extent of large megathrust earthquakes in the region
    Description: IGEPN
    Description: IRD
    Description: INSU‐CNRS
    Description: ANR
    Description: NERC
    Description: IRIS PASSCAL and NSF RAPID Program Award
    Description: ANID under Programa Formación de Capital Humano Avanzado, Becas Chile
    Description: UCA/JEDI project
    Keywords: 551.22 ; aftershocks ; Ecuador ; megathrust earthquake ; seismic tomography ; subduction zone ; velocity structure
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    Unraveling the Global Warming Mitigation Potential from Recycling Subway‐Related Excavated Soil and Rock in China Via Life Cycle Assessment (2021)
    Details
    Publication Date: 2021-07-21
    Description: Many cities across China are investing in subway projects, resulting in much subway construction activity, which has experienced a surge over the past decade. The construction activities inevitably cause a dramatic quantity of subway‐related excavated soil and rock (ESR). How to manage it with minimal environmental impact on our urban ecosystem remains an open question. The present study evaluates global warming potential (GWP, expressed by CO2 eq) from different ESR recycling and landfilling scenarios via a life cycle assessment (LCA) model based on primary field investigation combined with the LCA software database. The study results illustrate that recycling ESR can significantly reduce greenhouse gas emissions. In comparison with traditional construction materials, the scenarios found that a cumulative amount of 1.1 to 1.5 million tonnes (Mt) of CO2 eq emissions could have been mitigated by using ESR generated between 2010 and 2018 to produce baking‐free bricks and recycled baked brick. Using cost–benefit analysis, potential economic benefits from recycled sand and baking‐free bricks are found to reach US$9 million annually. The findings of this study could provide better recycling options for ESR‐related stakeholders. It is important to mention that there still is much work to be done before this recycling work can be popularized in China. Integr Environ Assess Manag 2021;17:639–650. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC)
    Description: KEY POINTS: This study focuses on the global warming potential (GWP) assessment of excavated soil and rock (ESR). Cumulative CO2 mitigation potential by recycling ESR was calculated. More than US$8 million profit could have been reached annually between 2006 and 2018. Cumulative CO2 mitigation potential could have been as high as 1.5 Mt from 2010 to 2018.
    Keywords: 333.7 ; Excavated soil and rock (ESR) ; Recycling ; CO2 mitigation ; Life cycle assessment ; Cost–benefit analysis
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    Geowissenschaftliche Mitteilungen - GMIT 73 (2021)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2021-03-29
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2018 enthält die Themenblöcke: GEOfokus: (Diskussionspapier | „Zum Stand der Geogesellschaften“), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Personalia, Nachrufe).
    Description: DFG, SUB Göttingen
    Description: journal
    Keywords: 550 ; Wissenschaftsorganisation und -pflege {Geologische Wissenschaften} ; Geowissenschaftliche Mitteilungen ; GMIT ; FID-GEO-DE-7
    Language: German
    Type: anthology , publishedVersion
    Format: 104
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    Geowissenschaftliche Mitteilungen - GMIT 76 (2021)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2021-03-29
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom Juni 2019 enthält die Themenblöcke: GEOfokus: (Sie brennen noch immer! Spontane unkontrollierte unterirdische Kohleflözbrände als gesellschaftlich relevante Aufgabe und wissenschaftliche Herausforderung für die Angewandte Geophysik), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Personalia, Nachrufe).
    Description: DFG, SUB Göttingen
    Description: journal
    Keywords: 550 ; Wissenschaftsorganisation und -pflege {Geologische Wissenschaften} ; GMIT ; Geowissenschaftliche Mitteilungen ; FID-GEO-DE-7
    Language: German
    Type: anthology , publishedVersion
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    Geowissenschaftliche Mitteilungen - GMIT 81 (2021)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2021-03-29
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2020 enthält die Themenblöcke: GEOfokus: (Herausforderungen der universitären Ausbildung in den Erdsystemwissenschaften in Deutschland – Ein Diskussionspapier), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Personalia, Nachrufe).
    Description: DFG, SUB Göttingen
    Description: journal
    Keywords: 550 ; Wissenschaftsorganisation und -pflege {Geologische Wissenschaften} ; GMIT ; Geowissenschaftliche Mitteilungen ; FID-GEO-DE-7
    Language: German
    Type: anthology , publishedVersion
    Format: 88
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  • 97
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    Assessing the Potential for Mobilization of Old Soil Carbon After Permafrost Thaw: A Synthesis of 14C Measurements From the Northern Permafrost Region (2021)
    Details
    Publication Date: 2021-07-05
    Description: The magnitude of future emissions of greenhouse gases from the northern permafrost region depends crucially on the mineralization of soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon (14C) to quantify the release of this “old” SOC as CO2 or CH4 to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 14C measurements from 51 sites in the northern permafrost region to assess the vulnerability of thawing SOC in tundra, forest, peatland, lake, and river ecosystems. We found that growing season soil 14C‐CO2 emissions generally had a modern (post‐1950s) signature, but that well‐drained, oxic soils had increased CO2 emissions derived from older sources following recent thaw. The age of CO2 and CH4 emitted from lakes depended primarily on the age and quantity of SOC in sediments and on the mode of emission, and indicated substantial losses of previously frozen SOC from actively expanding thermokarst lakes. Increased fluvial export of aged DOC and POC occurred from sites where permafrost thaw caused soil thermal erosion. There was limited evidence supporting release of previously frozen SOC as CO2, CH4, and DOC from thawing peatlands with anoxic soils. This synthesis thus suggests widespread but not universal release of permafrost SOC following thaw. We show that different definitions of “old” sources among studies hamper the comparison of vulnerability of permafrost SOC across ecosystems and disturbances. We also highlight opportunities for future 14C studies in the permafrost region.
    Description: Key Points: We compiled ~1,900 14C measurements of CO2, CH4, DOC, and POC from the northern permafrost region. Old carbon release increases in thawed oxic soils (CO2), thermokarst lakes (CH4 and CO2), and headwaters with thermal erosion (DOC and POC). Simultaneous and year‐long 14C analyses of CO2, CH4, DOC, and POC are needed to assess the vulnerability of permafrost carbon across ecosystems.
    Description: EC | H2020 | H2020 Priority Excellent Science | H2020 European Research Council (ERC) http://dx.doi.org/10.13039/100010663
    Description: Gouvernement du Canada | Natural Sciences and Engineering Research Council of Canada (NSERC) http://dx.doi.org/10.13039/501100000038
    Description: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Keywords: 551.9 ; permafrost thaw ; radiocarbon ; carbon dioxide ; methane ; dissolved organic carbon ; particulate organic carbon
    Type: article
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  • 98
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    Crystal structure of a calcium(II)–pyrroloquinoline quinone (PQQ) complex outside a protein environment (2021)
    5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2021-04-14
    Description: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases, and has been known for over 30 years. Crystal structures of Ca–MDH enzymes (MDH is methanol dehydrogenase) have been known for some time; however, crystal structures of PQQ with biorelevant metal ions have been lacking in the literature for decades. We report here the first crystal structure analysis of a Ca–PQQ complex outside the protein environment, namely, poly[[undecaaquabis(μ‐4,5‐dioxo‐4,5‐dihydro‐1H‐pyrrolo[2,3‐f]quinoline‐2,7,9‐tricarboxylato)tricalcium(II)] dihydrate], {[Ca3(C14H3N2O8)2(H2O)11]·2H2O}n. The complex crystallized as Ca3PQQ2·13H2O with Ca2+ in three different positions and PQQ3−, including an extensive hydrogen‐bond network. Similarities and differences to the recently reported structure with biorelevant europium (Eu2PQQ2) are discussed.
    Description: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases. The crystal structure of a Ca–PQQ complex (Ca3PQQ2·13H2O) is reported for the first time outside a protein environment. image
    Description: research
    Keywords: 548 ; pyrroloquinoline quinone ; calcium ; PQQ ; methanol dehydrogenase ; crystal structure ; FID-GEO-DE-7
    Language: English
    Type: article , publishedVersion
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  • 99
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    Mantle and Crustal Sources of Magmatic Activity of Klyuchevskoy and Surrounding Volcanoes in Kamchatka Inferred From Earthquake Tomography (2021)
    Details
    Publication Date: 2021-07-01
    Description: Klyuchevskoy and surrounding volcanoes in central Kamchatka form the Northern Group of Volcanoes (NGV), which is an area of particularly diverse and intensive Pleistocene‐Holocene volcanism. In this study, we present a new seismic tomographic model of the crust and uppermost mantle beneath NGV based on local earthquake data recorded by several permanent and temporary seismic networks including a large‐scale experiment that was conducted in 2015–2016 by an international scientific consortium. Having an unprecedented resolution for this part of Kamchatka, the new model reveals many features associated with the present and past volcanic activity within the NGV. In the upper crust, we found several prominent high‐velocity anomalies interpreted as traces of large basaltic shield volcanoes, which were hidden by more recent volcanic structures and sediments. We interpret the mantle structure to reflect asthenospheric flow up through a slab window below the Kamchatka‐Aleutian junction that feeds the entire NGV. The interaction of the hot asthenospheric material with fluids released from the slab determines the particular volcanic activity within the NGV. We argue that the eastern branch of the Central Kamchatka Depression, which is associated with a prominent low‐velocity anomaly in the uppermost mantle, was formed as a recent rift zone separating the NGV from the Kamchatka Eastern Ranges.
    Description: Key Points: We present a new high‐resolution seismic model of the crust and upper mantle beneath the Northern Group of Volcanoes in Kamchatka. The volcanoes of the Northern group are fed by an asthenosphere flow ascending from a slab window below the Kamchatka‐Aleutian junction. Eastern branch of the Central Kamchatka Depression is a rift separating the Northern Group of Volcanoes from the Eastern Ranges.
    Description: Russian Ministry of Science and Education http://dx.doi.org/10.13039/501100012190
    Description: Russian Science Foundation http://dx.doi.org/10.13039/100004111
    Description: RFBR http://dx.doi.org/10.13039/501100002261
    Description: European Union Horizon 2020 Research and Innovation Programme http://dx.doi.org/10.13039/501100012190
    Keywords: 551.2 ; seismic tomography ; subduction ; Klyuchevskoy Group of Volcanoes ; Shiveluch ; Kizimen ; Central Kamchatka Depression
    Type: article
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  • 100
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    Geowissenschaftliche Mitteilungen - GMIT 47 (2021)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2021-03-29
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom März 2012 enthält die Themenblöcke: GEOfokus: (Rohstoffe, die Basis unseres Wohlstandes ), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Personalia, Nachrufe).
    Description: DFG, SUB Göttingen
    Description: journal
    Keywords: 550 ; Wissenschaftsorganisation und -pflege {Geologische Wissenschaften} ; GMIT ; Geowissenschaftliche Mitteilungen ; FID-GEO-DE-7
    Language: German
    Type: anthology , publishedVersion
    Format: 79
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