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  • 2020-2024  (352)
  • 1990-1994  (102)
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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2667-2675 
    ISSN: 0009-2940
    Schlagwort(e): Alkene ligands ; 1,6-Dienes ; Nickel complex ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,6-Heptadiene Nickel(0) Complexes:rac/meso-(μ-η2,η2-C7{Ni(η 2,η2-C7H12)}2 und L-Ni(η2,η2-C7H12)Ni(CDT) dissolves in 1,6-heptadiene with displacement of the CDT to yield the dinuclear homoleptic product rac/meso-(μ- η2,η2-C7H12){Ni(η2, η2-C7H12)}2 (1) as a mixture of stereoisomers, in which the nickel atoms are trigonal-planar coordinated by a chelating 1,6-diene ligand and one C=C bond of a bridging diene ligand. The stereoisomers differ in the coordination mode of the bridging diene ligand.-The bridging diene ligand in 1 can be displaced by various donor/acceptor molecules. In pentane, 1 reacts with ethene to yield a solution of mononuclear (C2H4)Ni(η2,η2-C7H12) (2). With alkynes unstable complexes are formed of which the anticipated ethyne derivative (C2H2)Ni(η2,η2-C7H12) (3) decomposes explosively at - 100°C. With isocyanides, methylenephosphoranes, methyllithium, amines, pyridines, phosphanes, and phosphites (i.e. C, N, P donors) crystalline complexes of type L-Ni(η2.η2 C7H12) have been obtained, of which the derivatives with L=tBuN = C 4, Me3PCH2 5, LiCH3 6, C7H13N7, C5H5N 8, Me3P 9, iPr3P 10, Ph3P 11, (PhO)3P 12 are characterized here. For 11 the crystal structure has been determined.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 831-835 
    ISSN: 0170-2041
    Schlagwort(e): Boron neutron capture therapy ; 1-[1,7-Dicarba-closo-dodecaboran(12)-1-yl]aldoses ; 1-[m-Carboran-1-yl]aldoses ; Boranes ; Carbohydrates ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Monolithiated 1,7-dicarba-closo-dodecaborane(12) reacts with O-isopropylidene derivatives of D-erythrono-1,4-lactone (1), L-mannono-1,4-lactone (3) and with tetra-O-trimethylsilylated D-glucono-1,5-lactone (2) and D-gulono-1,4-lactone (4) to give the title compounds after deprotection. An X-ray structure analysis of the protected L-mannofuranose carborane derivative 9 reveals that the more stable anomer has the β-L configuration.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 3
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    Unbekannt
    In:  Protokoll über das 14. Kolloquium Elektromagnetische Tiefenforschung: Borkheide, 25.05.- 29.05.1992
    Publikationsdatum: 2022-07-24
    Sprache: Deutsch
    Materialart: info:eu-repo/semantics/conferenceObject
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  • 4
    Publikationsdatum: 2023-01-13
    Beschreibung: The region of West Bohemia and Upper Palatinate belongs to the West Bohemian Massif. The study area is situated at the junction of three different Variscan tectonic units and hosts the ENE-WSW trending Ohře Rift as well as many different fault systems. The entire region is characterized by ongoing magmatic processes in the intra-continental lithospheric mantle expressed by a series of phenomena, including e.g. the occurrence of repeated earthquake swarms and massive degassing of mantle derived CO2 in form of mineral springs and mofettes. Ongoing active tectonics is mainly manifested by Cenozoic volcanism represented by different Quaternary volcanic structures. All these phenomena make the Ohře Rift a unique target area for European intra-continental geo-scientific research. With magnetotelluric (MT) measurements we image the subsurface distribution of the electrical resistivity and map possible fluid pathways. Two-dimensional (2D) inversion results by Muñoz et al. (2018) reveal a conductive channel in the vicinity of the earthquake swarm region that extends from the lower crust to the surface forming a pathway for fluids into the region of the mofettes. A second conductive channel is present in the south of their model; however, their 2D inversions allow ambiguous interpretations of this feature. Therefore, we conducted a large 3D MT field experiment extending the study area towards the south. The 3D inversion result matches well with the known geology imaging different fluid/magma reservoirs at crust-mantle depth and mapping possible fluid pathways from the reservoirs to the surface feeding known mofettes and spas. A comparison of 3D and 2D inversion results suggests that the 2D inversion results are considerably characterized by 3D and off-profile structures. In this context, the new results advocate for the swarm earthquakes being located in the resistive host rock surrounding the conductive channels; a finding in line with observations e.g. at the San Andreas Fault, California.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/article
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  • 5
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    Unbekannt
    Zentralinstitut Physik der Erde
    In:  Veröffentlichungen des Zentralinstituts Physik der Erde
    Publikationsdatum: 2021-01-25
    Sprache: Deutsch
    Materialart: info:eu-repo/semantics/book
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  • 6
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    Unbekannt
    Zentralinstitut Physik der Erde
    In:  Veröffentlichungen des Zentralinstituts Physik der Erde
    Publikationsdatum: 2021-01-25
    Sprache: Deutsch
    Materialart: info:eu-repo/semantics/book
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  • 7
    Publikationsdatum: 2023-04-26
    Materialart: info:eu-repo/semantics/article
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  • 8
    Publikationsdatum: 2024-02-07
    Beschreibung: Machine learning (ML) and in particular deep learning (DL) methods push state-of-the-art solutions for many hard problems, for example, image classification, speech recognition, or time series forecasting. In the domain of climate science, ML and DL are known to be effective for identifying causally linked modes of climate variability as key to understand the climate system and to improve the predictive skills of forecast systems. To attribute climate events in a data-driven way, we need sufficient training data, which is often limited for real-world measurements. The data science community provides standard data sets for many applications. As a new data set, we introduce a consistent and comprehensive collection of climate indices typically used to describe Earth System dynamics. Therefore, we use 1000-year control simulations from Earth System Models. The data set is provided as an open-source framework that can be extended and customized to individual needs. It allows users to develop new ML methodologies and to compare results to existing methods and models as benchmark. For example, we use the data set to predict rainfall in the African Sahel region and El Niño Southern Oscillation with various ML models. Our aim is to build a bridge between the data science community and researchers and practitioners from the domain of climate science to jointly improve our understanding of the climate system.
    Materialart: Article , PeerReviewed
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  • 9
    Publikationsdatum: 2024-02-07
    Beschreibung: Background: Syngnathids are a highly derived and diverse fish clade comprising the pipefishes, pipe-horses, and seahorses. They are characterized by a plethora of iconic traits that increasingly capture the attention of biologists, including geneticists, ecologists, and developmental biologists. The current understanding of the origins of their derived body plan is, however, hampered by incomplete and limited descriptions of the early syngnathid ontogeny. Results: We provide a comprehensive description of the development of Nerophis ophidion, Syngnathus typhle, and Hippocampus erectus from early cleavage stages to release from the male brooding organ and beyond, including juvenile development. We comparatively describe skeletogenesis with a particular focus on dermal bony plates, the snout-like jaw morphology, and appendages. Conclusions: This most comprehensive and detailed account of syngnathid development to date suggests that convergent phenotypes (e.g., reduction and loss of the caudal fins), likely arose by distinct ontogenetic means in pipefishes and seahorses. Comparison of the ontogenetic trajectories of S. typhle and H. erectus provides indications that characteristic features of the seahorse body plan result from developmental truncation. Altogether, this work provides a valuable resource and framework for future research to understand the evolution of the outlandish syngnathid morphology from a developmental perspective.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 10
    Publikationsdatum: 2024-02-07
    Beschreibung: Dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethyl sulfoxide (DMSO) were measured at the Boknis Eck Time Series Station (BE, Eckernförde Bay, SW Baltic Sea) during the period February 2009–December 2018. Our results show considerable interannual and seasonal variabilities in the mixed-layer concentrations of DMS, total DMSP (DMSPt) and total DMSO (DMSOt). Positive correlations were found between particulate DMSP (DMSPp) and particulate DMSO (DMSOp) as well as DMSPt and DMSOt in the mixed layer, suggesting a similar source for both compounds. The decreasing long-term trends, observed for DMSPt and DMS in the mixed layer, were linked to the concurrent trend of the sum of 19′-hexanoyloxyfucoxanthin and 19′-butanoyloxy-fucoxanthin, which are the marker pigments of prymnesiophytes and chrysophytes, respectively. Major Baltic inflow (MBI) events influenced the distribution of sulfur compounds due to phytoplankton community changes, and sediment might be a potential source for DMS in the bottom layer during seasonal hypoxia/anoxia at BE. A modified algorithm based on the phytoplankton pigments reproduces the DMSPp : Chl a ratios well during this study and could be used to estimate future surface (5 m) DMSPp concentrations at BE.
    Materialart: Article , PeerReviewed
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  • 11
    Publikationsdatum: 2023-02-08
    Beschreibung: Coastal areas contribute significantly to the emissions of methane (CH4) from the ocean. In order to decipher its temporal variability in the whole water column, dissolved CH4 was measured on a monthly basis at the Boknis Eck Time-series Station (BE) located in the Eckernförde Bay (SW Baltic Sea) from 2006 to 2017. BE has a water depth of about 28 m and dissolved CH4 was measured at six water depths ranging from 0 to 25 m. In general CH4 concentrations increased with depth, indicating a sedimentary release of CH4. Pronounced enhancement of the CH4 concentrations in the bottom layer (15–25 m) was found during February, May–June and October. CH4 was not correlated with Chlorophyll a or O2 over the measurement period. Unusually high CH4 concentrations (of up to 696 nM) were sporadically observed in the upper layer (0–10 m) (e.g. in November 2013 and December 2014) and were coinciding with Major Baltic Inflow (MBI) events. Surface CH4 concentrations were always supersaturated throughout the monitoring period, indicating that the Eckernförde Bay is an intense but highly variable source of atmospheric CH4. We did not detect significant temporal trends in CH4 concentrations or emissions, despite of ongoing environmental changes such as warming and deoxygenation in the Eckernförde Bay. Overall, the CH4 variability at BE is driven by a complex interplay of various biological and physical processes.
    Materialart: Article , PeerReviewed
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  • 12
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    Unbekannt
    In:  Journal of Geophysical Research: Solid Earth
    Publikationsdatum: 2024-02-05
    Beschreibung: Teleseismic back-projection imaging has emerged as a powerful tool for understanding the rupture propagation of large earthquakes. However, its application often suffers from artifacts related to the receiver array geometry. We developed a teleseismic back-projection technique that can accommodate data from multiple arrays. Combined processing of P and pP waveforms may further improve the resolution. The method is suitable for defining arrays ad-hoc to achieve a good azimuthal distribution for most earthquakes. We present a catalog of short-period rupture histories (0.5–2.0 Hz) for all earthquakes from 2010 to 2022 with MW ≥ 7.5 and depth less than 200 km (56 events). The method provides automatic estimates of rupture length, directivity, speed, and aspect ratio, a proxy for rupture complexity. We obtained short-period rupture length scaling relations that are in good agreement with previously published relations based on estimates of total slip. Rupture speeds were consistently in the sub-Rayleigh regime for thrust and normal earthquakes, whereas a tenth of strike-slip events propagated at supershear speeds. Many rupture histories exhibited complex behaviors, for example, rupture on conjugate faults, bilateral propagation, and dynamic triggering by a P wave. For megathrust earthquakes, ruptures encircling asperities were frequently observed, with downdip, updip, and balanced patterns. Although there is a preference for short-period emissions to emanate from central and downdip parts of the megathrust, emissions updip of the main asperity are more frequent than suggested by earlier results.
    Materialart: info:eu-repo/semantics/article
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  • 13
    Publikationsdatum: 2024-02-07
    Beschreibung: Eutrophication is accelerating the recent expansion of oxygen-depleted coastal marine environments. Several bolivinid foraminifera are abundant in these oxygen-depleted settings, and take up nitrate through the pores in their shells for denitrification. This makes their pore density a possible nitrate proxy. This study documents three aspects related to the porosity of bolivinids. 1. A new automated image analysis technique to determine the number of pores in bolivinids is tested. 2. The pore patterns of Bolivina spissa from five different ocean settings are analysed. The relationship between porosity, pore density and mean pore size significantly differs between the studied locations. Their porosity is mainly controlled by the size of the pores at the Gulf of Guayaquil (Peru), but by the number of pores at other studied locations. This might be related to the presence of a different cryptic Bolivina species in the Gulf of Guayaquil. 3. The pore densities of closely related bolivinids in core-top samples are calibrated as a bottom-water nitrate proxy. Bolivina spissa and Bolivina subadvena showed the same correlation between pore density and bottom-water nitrate concentrations, while the pore density of Bolivina argentea and Bolivina subadvena accumeata is much higher.
    Materialart: Article , PeerReviewed
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  • 14
    Publikationsdatum: 2024-02-07
    Beschreibung: Sponges underpin the productivity of coral reefs, yet few of their microbial symbionts have been functionally characterised. Here we present an analysis of ~1200 metagenome-assembled genomes (MAGs) spanning seven sponge species and 25 microbial phyla. Compared to MAGs derived from reef seawater, sponge-associated MAGs were enriched in glycosyl hydrolases targeting components of sponge tissue, coral mucus and macroalgae, revealing a critical role for sponge symbionts in cycling reef organic matter. Further, visualisation of the distribution of these genes amongst symbiont taxa uncovered functional guilds for reef organic matter degradation. Genes for the utilisation of sialic acids and glycosaminoglycans present in sponge tissue were found in specific microbial lineages that also encoded genes for attachment to sponge-derived fibronectins and cadherins, suggesting these lineages can utilise specific structural elements of sponge tissue. Further, genes encoding CRISPR and restriction-modification systems used in defence against mobile genetic elements were enriched in sponge symbionts, along with eukaryote-like gene motifs thought to be involved in maintaining host association. Finally, we provide evidence that many of these sponge-enriched genes are laterally transferred between microbial taxa, suggesting they confer a selective advantage within the sponge niche and therefore play a critical role in host ecology and evolution.
    Materialart: Article , PeerReviewed
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  • 15
    Publikationsdatum: 2023-03-31
    Beschreibung: We present the first version of the Ocean Circulation and Carbon Cycling (OC3) working group database, of oxygen and carbon stable isotope ratios from benthic foraminifera in deep ocean sediment cores from the Last Glacial Maximum (LGM, 23-19 ky) to the Holocene (〈10 ky) with a particular focus on the early last deglaciation (19-15 ky BP). It includes 287 globally distributed coring sites, with metadata, isotopic and chronostratigraphic information, and age models. A quality check was performed for all data and age models, and sites with at least millennial resolution were preferred. Deep water mass structure as well as differences between the early deglaciation and LGM are captured by the data, even though its coverage is still sparse in many regions. We find high correlations among time series calculated with different age models at sites that allow such analysis. The database provides a useful dynamical approach to map physical and biogeochemical changes of the ocean throughout the last deglaciation.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , peerRev
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  • 16
    Publikationsdatum: 2024-02-07
    Beschreibung: The climactic Los Chocoyos (LCY) eruption from Atitlán caldera (Guatemala) is a key chronostratigraphic marker for the Quaternary period given the extensive distribution of its deposits that reached both the Pacific and Atlantic Oceans. Despite LCY tephra being an important marker horizon, a radioisotopic age for this eruption has remained elusive. Using zircon (U–Th)/He geochronology, we present the first radioisotopically determined eruption age for the LCY of 75 ± 2 ka. Additionally, the youngest zircon crystallization 238U–230Th rim ages in their respective samples constrain eruption age maxima for two other tephra units that erupted from Atitlán caldera, W-Fall (130 +16/−14 ka) and I-Fall eruptions (56 +8.2/−7.7 ka), which under- and overlie LCY tephra, respectively. Moreover, rim and interior zircon dating and glass chemistry suggest that before eruption silicic magma was stored for 〉80 kyr, with magma accumulation peaking within ca. 35 kyr before the LCY eruption during which the system may have developed into a vertically zoned magma chamber. Based on an updated distribution of LCY pyroclastic deposits, a new conservatively estimated volume of ~1220 ± 150 km3 is obtained (volcanic explosivity index VEI 〉 8), which confirms the LCY eruption as the first-ever recognized supereruption in Central America.
    Materialart: Article , PeerReviewed
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  • 17
    Publikationsdatum: 2023-02-08
    Beschreibung: A new autotrophic hydrogen‐oxidizing Chromatiaceae bacterium, namely bacterium CTD079, was enriched from a water column sample at 1500 m water depth in the southern Pacific Ocean. Based on the phylogeny of 16S rRNA genes it was closely related to a scaly snail endosymbiont (99.2% DNA sequence identity) whose host so far is only known to colonize hydrothermal vents along the Indian ridge. The average nucleotide identity between the genomes of CTD079 and the snail endosymbiont was 91%. The observed differences likely reflect adaptations to their specific habitats. For example, CTD079 encodes additional enzymes like the formate dehydrogenase increasing the organism's spectrum of energy generation pathways. Other additional physiological features of CTD079 included the increase of viral defense strategies, secretion systems and specific transporters for essential elements. These important genome characteristics suggest an adaptation to life in the open ocean.
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  • 18
  • 19
    Publikationsdatum: 2024-02-07
    Beschreibung: Glacial isostatic adjustment (GIA) is the ongoing response of the viscoelastic solid Earth, oceans and the gravitational field to the previous burden of the ice loads. The Earth’s surface was once covered with massive ice sheets, and melting of these ice sheets is still reshaping coastlines and affecting sea-level. To reconstruct former sea level and be able to predict future changes, it is necessary to constrain the rheological properties of the Earth’s structure. Widely used data to constrain Earth’s interior are sea-level indicators. In the first part of the thesis, we propose a statistical method that quantifies a relationship between the sea-level indicator and a relative sea level in order to compare it to GIA predictions. A statistical method is based on consideration of spatial and temporal probability density functions, derived from the age and elevation of each indicator. This method allows a more rigorous approach to validation with sea-level data and possibility to include low-quality data. We verified method performance in the Hudson Bay, Canada as a test run before applying it to the SW Fennoscandia. SW Fennoscandia identifies as an area where lateral heterogeneity is likely to exist. The south-western part of Fennoscandia lies on the crustal boundary called the Trans-European Suture Zone (TESZ), or the Tornquist Zone. GIA models have two representations of Earth’s structure; radially symmetric (1D), where the rheology only varies vertically, and lateral or 3D variations of viscosity structure. In this thesis, we compare glacial isostatic adjustment reconstructions with both representations of the rheology. Results from the 1D model show variations in the viscosity structure between the area near to the centre of the former ice sheet and the areas at the margin of the ice sheet. Hence, we verify the importance of including lateral variations in GIA models in this region. Application of 3D models displays the sensitivity of model parameters to crustal deformation. German Baltic coast yields thinner lithosphere than TESZ region and near-centre region. Additionally, in the TESZ region, we notice a steep increase in viscosity of the asthenosphere and upper-mantle. Furthermore, we compared two different global ice histories (ICE5G and ICE6G_C) and concluded that the marginal areas are more sensitive to different deglaciations, and we propose to use regional ice histories to constrain GIA models better. Apart from the new statistical method, this study sets a ground for future GIA studies in complex tectonic regions and demonstrates the importance of including laterally heterogeneous Earth structure in GIA models.
    Materialart: Thesis , NonPeerReviewed
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  • 20
    Publikationsdatum: 2023-10-24
    Beschreibung: An experimental platform for dynamic diamond anvil cell (dDAC) research has been developed at the High Energy Density (HED) Instrument at the European X-ray Free Electron Laser (European XFEL). Advantage was taken of the high repetition rate of the European XFEL (up to 4.5 MHz) to collect pulse-resolved MHz X-ray diffraction data from samples as they are dynamically compressed at intermediate strain rates (≤103 s−1), where up to 352 diffraction images can be collected from a single pulse train. The set-up employs piezo-driven dDACs capable of compressing samples in ≥340 µs, compatible with the maximum length of the pulse train (550 µs). Results from rapid compression experiments on a wide range of sample systems with different X-ray scattering powers are presented. A maximum compression rate of 87 TPa s−1 was observed during the fast compression of Au, while a strain rate of ∼1100 s−1 was achieved during the rapid compression of N2 at 23 TPa s−1.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/article
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  • 21
  • 22
    Publikationsdatum: 2023-02-08
    Beschreibung: Idealized models or emulators of volcanic aerosol forcing have been widely used to reconstruct the spatiotemporal evolution of past volcanic forcing. However, existing models, including the most recently developed Easy Volcanic Aerosol (EVA; Toohey et al., doi: 10.5194/gmd‐2016‐83), (i) do not account for the height of injection of volcanic SO urn:x-wiley:jgrd:media:jgrd55987:jgrd55987-math-0001; (ii) prescribe a vertical structure for the forcing; and (iii) are often calibrated against a single eruption. We present a new idealized model, EVA_H, that addresses these limitations. Compared to EVA, EVA_H makes predictions of the global mean stratospheric aerosol optical depth that are (i) similar for the 1979–1998 period characterized by the large and high‐altitude tropical SO urn:x-wiley:jgrd:media:jgrd55987:jgrd55987-math-0002 injections of El Chichón (1982) and Mount Pinatubo (1991); (ii) significantly improved for the 1998–2015 period characterized by smaller eruptions with a large variety of injection latitudes and heights. Compared to EVA, the sensitivity of volcanic forcing to injection latitude and height in EVA_H is much more consistent with results from climate models that include interactive aerosol chemistry and microphysics, even though EVA_H remains less sensitive to eruption latitude than the latter models. We apply EVA_H to investigate potential biases and uncertainties in EVA‐based volcanic forcing data sets from phase 6 of the Coupled Model Intercomparison Project (CMIP6). EVA and EVA_H forcing reconstructions do not significantly differ for tropical high‐altitude volcanic injections. However, for high‐latitude or low‐altitude injections, our reconstructed forcing is significantly lower. This suggests that volcanic forcing in CMIP6 last millenium experiments may be overestimated for such eruptions.
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  • 23
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    Unbekannt
    Oxford University Press (OUP)
    In:  EPIC3FEMS Microbiology Reviews, Oxford University Press (OUP), 46(6), pp. fuac028-fuac028, ISSN: 0168-6445
    Publikationsdatum: 2024-01-02
    Beschreibung: Tropical coral reefs are hotspots of marine productivity, owing to the association of reef-building corals with endosymbiotic algae and metabolically diverse bacterial communities. However, the functional importance of fungi, well-known for their contribution to shaping terrestrial ecosystems and global nutrient cycles, remains underexplored on coral reefs. We here conceptualize how fungal functional traits may have facilitated the spread, diversification, and ecological adaptation of marine fungi on coral reefs. We propose that functions of reef-associated fungi may be diverse and go beyond their hitherto described roles of pathogens and bioeroders, including but not limited to reef-scale biogeochemical cycles and the structuring of coral-associated and environmental microbiomes via chemical mediation. Recent technological and conceptual advances will allow the elucidation of the physiological, ecological, and chemical contributions of understudied marine fungi to coral holobiont and reef ecosystem functioning and health and may help provide an outlook for reef management actions.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , peerRev
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  • 24
    Publikationsdatum: 1994-12-01
    Print ISSN: 0170-9739
    Digitale ISSN: 1431-5858
    Thema: Physik
    Publiziert von Springer
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  • 25
    Publikationsdatum: 1991-11-01
    Print ISSN: 0888-7543
    Digitale ISSN: 1089-8646
    Thema: Biologie , Medizin
    Publiziert von Elsevier
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  • 26
    Publikationsdatum: 1990-03-01
    Print ISSN: 0170-9739
    Digitale ISSN: 1431-5858
    Thema: Physik
    Publiziert von Springer
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  • 27
    Publikationsdatum: 2023-06-21
    Beschreibung: 〈jats:p〉Marine microorganisms contribute to the health of the global ocean by supporting the marine food web and regulating biogeochemical cycles. Assessing marine microbial diversity is a crucial step towards understanding the global ocean. The waters surrounding Iceland are a complex environment where relatively warm salty waters from the Atlantic cool down and sink down to the deep. Microbial studies in this area have focused on photosynthetic micro- and nanoplankton mainly using microscopy and chlorophyll measurements. However, the diversity and function of the bacterial and archaeal picoplankton remains unknown. Here, we used a co-assembly approach supported by a marine mock community to reconstruct metagenome-assembled genomes (MAGs) from 31 metagenomes from the sea surface and seafloor of four oceanographic sampling stations sampled between 2015 and 2018. The resulting 219 MAGs include 191 bacterial, 26 archaeal and two eukaryotic MAGs to bridge the gap in our current knowledge of the global marine microbiome.〈/jats:p〉
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , NonPeerReviewed
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  • 28
    Publikationsdatum: 2024-02-07
    Beschreibung: Ice-nucleating particles (INPs) have a large impact on the climate-relevant properties of clouds over the oceans. Studies have shown that sea spray aerosols (SSAs), produced upon bursting of bubbles at the ocean surface, can be an important source of marine INPs, particularly during periods of enhanced biological productivity. Recent mesocosm experiments using natural seawater spiked with nutrients have revealed that marine INPs are derived from two separate classes of organic matter in SSAs. Despite this finding, existing parameterizations for marine INP abundance are based solely on single variables such as SSA organic carbon (OC) or SSA surface area, which may mask specific trends in the separate classes of INP. The goal of this paper is to improve the understanding of the connection between ocean biology and marine INP abundance by reporting results from a field study and proposing a new parameterization of marine INPs that accounts for the two associated classes of organic matter. The PEACETIME cruise took place from 10 May to 10 June 2017 in the Mediterranean Sea. Throughout the cruise, INP concentrations in the surface microlayer (INPSML) and in SSAs (INPSSA) produced using a plunging aquarium apparatus were continuously monitored while surface seawater (SSW) and SML biological properties were measured in parallel. The organic content of artificially generated SSAs was also evaluated. INPSML concentrations were found to be lower than those reported in the literature, presumably due to the oligotrophic nature of the Mediterranean Sea. A dust wet deposition event that occurred during the cruise increased the INP concentrations measured in the SML by an order of magnitude, in line with increases in iron in the SML and bacterial abundances. Increases in INPSSA were not observed until after a delay of 3 days compared to increases in the SML and are likely a result of a strong influence of bulk SSW INPs for the temperatures investigated (T=−18 ∘C for SSAs, T=−15 ∘C for SSW). Results confirmed that INPSSA are divided into two classes depending on their associated organic matter. Here we find that warm (T≥−22 ∘C) INPSSA concentrations are correlated with water-soluble organic matter (WSOC) in the SSAs, but also with SSW parameters (particulate organic carbon, POCSSW and INPSSW,−16C) while cold INPSSA (T〈−22 ∘C) are correlated with SSA water-insoluble organic carbon (WIOC) and SML dissolved organic carbon (DOC) concentrations. A relationship was also found between cold INPSSA and SSW nano- and microphytoplankton cell abundances, indicating that these species might be a source of water-insoluble organic matter with surfactant properties and specific IN activities. Guided by these results, we formulated and tested multiple parameterizations for the abundance of INPs in marine SSAs, including a single-component model based on POCSSW and a two-component model based on SSA WIOC and OC. We also altered a previous model based on OCSSA content to account for oligotrophy of the Mediterranean Sea. We then compared this formulation with the previous models. This new parameterization should improve attempts to incorporate marine INP emissions into numerical models.
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  • 29
    Publikationsdatum: 2024-01-25
    Beschreibung: Understanding wildfire dynamics in space and over time is critical for wildfire control and management. In this study, fire data from European Space Agency (ESA) MODIS fire product (ESA/CCI/FireCCI/5_1) with ≥ 70% confidence level was used to characterise spatial and temporal variation in fire frequency in Zimbabwe between 2001 and 2020. Results showed that burned area increased by 16% from 3,689 km2 in 2001 to 6,130 km2 in 2011 and decreased in subsequent years reaching its lowest in 2020 (1,161km2). Over, the 20-year period, an average of 40,086.56 km2 of land was burned annually across the country. In addition, results of the regression analysis based on Generalised Linear Model illustrated that soil moisture, wind speed and temperature significantly explained variation in burned area. Moreover, the four-year lagged annual rainfall was positively related with burned area suggesting that some parts in the country (southern and western) are characterised by limited herbaceous production thereby increasing the time required for the accumulation of sufficient fuel load. The study identified major fire hotspots in Zimbabwe through the integration of remotely sensed fire data within a spatially analytical framework. This can provide useful insights into fire evolution which can be used to guide wildfire control and management in fire prone ecosystems. Moreover, resource allocation for fire management and mitigation can be optimised through targeting areas most affected by wildfires especially during the dry season where wildfire activity is at its peak.
    Sprache: Englisch
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  • 30
    Publikationsdatum: 2024-02-07
    Beschreibung: The Arctic is warming 2–3 times faster than the global average, leading to a decrease in Arctic sea ice extent, thickness, and associated changes in sea ice structure. These changes impact sea ice habitat properties and the ice-associated ecosystems. Sea-ice algal blooms provide various algal-derived carbon sources for the bacterial and archaeal communities within the sea ice. Here, we detail the transition of these communities from winter through spring to early summer during the Norwegian young sea ICE (N-ICE2015) expedition. The winter community was dominated by the archaeon Candidatus Nitrosopumilus and bacteria belonging to the Gammaproteobacteria (Colwellia, Kangiellaceae, and Nitrinocolaceae), indicating that nitrogen-based metabolisms, particularly ammonia oxidation to nitrite by Cand. Nitrosopumilus was prevalent. At the onset of the vernal sea-ice algae bloom, the community shifted to the dominance of Gammaproteobacteria (Kangiellaceae, Nitrinocolaceae) and Bacteroidia (Polaribacter), while Cand. Nitrosopumilus almost disappeared. The bioinformatically predicted carbohydrate-active enzymes increased during spring and summer, indicating that sea-ice algae-derived carbon sources are a strong driver of bacterial and archaeal community succession in Arctic sea ice during the change of seasons. This implies a succession from a nitrogen metabolism-based winter community to an algal-derived carbon metabolism-based spring/ summer community.
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  • 31
    Publikationsdatum: 2024-02-07
    Beschreibung: Three volcanic arcs have been the source of New Zealand's volcanic activity since the Neogene: Northland arc, Coromandel Volcanic Zone (CVZ) and Taupō Volcanic Zone (TVZ). The eruption chronology for the Quaternary, sourced by the TVZ, is well studied and established, whereas the volcanic evolution of the precursor arc systems, like the CVZ (central activity c. 18 to 2 Ma), is poorly known due to limited accessibility to, or identification of, onshore volcanic deposits and their sources. Here, we investigate the marine tephra record of the Neogene, mostly sourced by the CVZ, of cores from IODP Exp. 375 (Sites U1520 and U1526), ODP Leg 181 (Sites 1123, 1124 and 1125), IODP Leg 329 (Site U1371) and DSDP Leg 90 (Site 594) offshore of New Zealand. In total, we identify 306 primary tephra layers in the marine sediments. Multi-approach age models (e.g. biostratigraphy, zircon ages) are used in combination with geochemical fingerprinting (major and trace element compositions) and the stratigraphic context of each marine tephra layer to establish 168 tie-lines between marine tephra layers from different holes and sites. Following this approach, we identify 208 explosive volcanic events in the Neogene between c. 17.5 and 2.6 Ma. This is the first comprehensive study of New Zealand's Neogene explosive volcanism established from tephrochronostratigraphic studies, which reveals continuous volcanic activity between c. 12 and 2.6 Ma with an abrupt compositional change at c. 4.5 Ma, potentially associated with the transition from CVZ to TVZ. Key Points New Zealand's Neogene explosive volcanism based on the marine tephra record Geochemical fingerprinting of marine tephra layers across the study area to establish volcanic events Insights into geochemical variations with time, repose times and spatiotemporal distribution
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  • 32
    Publikationsdatum: 2019-06-28
    Beschreibung: An experimental investigation was conducted on the engine/airframe integration aerodynamics for potential high-lift aircraft configurations. The model consisted of a semispan wing with a double-isolated flap system and a Krueger leading edge device. The advanced propeller and the powered nacelle were tested and aerodynamic characteristics of the combined system are presented. It was found that the lift coefficient of the powered wing could be increased by the propeller slipstream when the rotational speed was increased and high-lift devices were deployed. Moving the nacelle/propeller closer to the wing in the vertical direction indicated higher lift augmentation than a shift in the longitudinal direction. A pitch-down nacelle inclination enhanced the lift performance of the system much better than vertical and horizontal variation of the nacelle locations and showed that the powered wing can sustain higher angles of attack near maximum lift performance.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA PAPER 92-0388
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  • 33
    Publikationsdatum: 2023-06-21
    Beschreibung: Springtime Arctic mixed-phase convection over open water in the Fram Strait as observed during the recent ACLOUD (Arctic CLoud Observations Using airborne measurements during polar Day) field campaign is simulated at turbulence-resolving resolutions. The first objective is to assess the skill of large-eddy simulation (LES) in reproducing the observed mixed-phase convection. The second goal is to then use the model to investigate how aerosol modulates the way in which turbulent mixing and clouds transform the low-level air mass. The focus lies on the low-level thermal structure and lapse rate, the heating efficiency of turbulent entrainment, and the low-level energy budget. A composite case is constructed based on data collected by two research aircraft on 18 June 2017. Simulations are evaluated against independent datasets, showing that the observed thermodynamic, cloudy, and turbulent states are well reproduced. Sensitivity tests on cloud condensation nuclei (CCN) concentration are then performed, covering a broad range between pristine polar and polluted continental values. We find a significant response in the resolved mixed-phase convection, which is in line with previous LES studies. An increased CCN substantially enhances the depth of convection and liquid cloud amount, accompanied by reduced surface precipitation. Initializing with the in situ CCN data yields the best agreement with the cloud and turbulence observations, a result that prioritizes its measurement during field campaigns for supporting high-resolution modeling efforts. A deeper analysis reveals that CCN significantly increases the efficiency of radiatively driven entrainment in warming the boundary layer. The marked strengthening of the thermal inversion plays a key role in this effect. The low-level heat budget shifts from surface driven to radiatively driven. This response is accompanied by a substantial reduction in the surface energy budget, featuring a weakened flow of solar radiation into the ocean. Results are interpreted in the context of air–sea interactions, air mass transformations, and climate feedbacks at high latitudes.
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  • 34
    Publikationsdatum: 2024-02-14
    Beschreibung: Drylands in sub-Saharan Africa are strongly affected by the impacts of climate change. Temperature increases, changes in rainfall patterns, and land degradation pose serious threats to food security, health, and water availability in the region. The increase in livelihood insecurity can in turn trigger migration as a way to adapt or cope with stress. Based on 89 original case studies, this study uses review and meta-analytical techniques to systematically explore the relationship between environmental change, adaptation, and migration in rural areas in sub-Saharan drylands. We show that households use a diverse range of strategies to respond to environmental hardships in different livelihood and ecological contexts. While migration is common in some communities, it is of less relevance to others, and it can take various forms. Our findings indicate that migration is often used as a complementary strategy to other forms of adaptation, which can vary depending on situational needs. We use cluster analysis to identify adaptation clusters and show how linked response strategies differ by socioeconomic conditions. We find that migration can serve as a last resort measure for highly vulnerable groups, or be used in combination with in-situ strategies for diversifying income and adapting agricultural practices. Our results have important implications highlighting the role of local conditions and complementary forms of coping and adaptation for understanding environmental migration.
    Sprache: Englisch
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  • 35
    Publikationsdatum: 2024-04-22
    Beschreibung: ALKOR cruise AL590 took place as part of the project CONMAR (https://conmarmunition.eu/) which is part of the DAM mission sustainMare (https://www.sustainmare.de/). It was the continuation of the munition monitoring started within the BMBF‐funded project UDEMM (Environmental Monitoring for the Delaboration of Munition in the Sea; https://udemm.geomar.de/), the EMFF (European Maritime and Fisheries Fund) ‐funded projects BASTA (Boost Applied munition detection through Smart data detection in and AI workflows; https://www.basta‐munition.eu) and ExPloTect (Ex‐situ, near‐real‐time detection compound detection in seawater). ALKOR worked for two weeks in the Baltic Sea in the munition dumpsites Kolberger Heide, Falshöft, in Lübeck Bight and west of Rügen. Munition sites were mapped via hydroacoustic (multibeam and synthetic aperture sonar) and visual (ROV and towed camera) methods. Water samples were taken for explosive- type compounds and eDNA analysis and sediment samples for macro faunal distribution studies. A change of crew happened on 24th March in Neustadt i.H. with support of the Coast Guard t of the federal police.
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  • 36
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    Deutsche Gesellschaft für Meeresforschung
    In:  DGM-Mitteilungen, 1994 (3). pp. 3-9.
    Publikationsdatum: 2016-11-03
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  • 37
    Publikationsdatum: 2024-04-15
    Beschreibung: Submarine groundwater discharge (SGD) is a globally important process supplying nutrients and trace elements to the coastal environment, thus playing a pivotal role in sustaining marine primary productivity. Along with nutrients, groundwater also contains allochthonous microbes that are discharged from the terrestrial subsurface into the sea. Currently, little is known about the interactions between groundwater‐borne and coastal seawater microbial populations, and groundwater microbes' role upon introduction to coastal seawater populations. Here, we investigated seawater microbial abundance, activity and diversity in a site strongly influenced by SGD. In addition, through laboratory‐controlled bottle incubations, we mimicked different mixing scenarios between groundwater and seawater. Our results demonstrate that the addition of 0.1 μm filtered groundwater stimulated heterotrophic activity and increased microbial abundance compared to control coastal seawater, whereas 0.22 μm filtration treatments induced primary productivity and Synechococcus growth. 16S rRNA gene sequencing showed a strong shift from a SAR11‐rich community in the control samples to Rhodobacteraceae dominance in the 〈0.1 μm treatment, in agreement with Rhodobacteraceae enrichment in the SGD field site. These results suggest that microbes delivered by SGD may affect the abundance, activity and diversity of intrinsic microbes in coastal seawater, highlighting the cryptic interplay between groundwater and seawater microbes in coastal environments, which has important implications for carbon cycling. Plain Language Summary Submarine groundwater discharge (SGD) is an important process where groundwater flows into the ocean along the coast. When the groundwater mixes with seawater, the microbes from both sources interact with each other, which can impact the diversity, activity, and amount of microbes in the coastal environment. Currently, little is known about how groundwater‐borne microbes affect marine microbial populations. Our research shows that when groundwater microbes are removed before mixing groundwater with seawater, the abundance and activity of certain microbes that consume organic matter significantly increase. Additionally, we noticed a significant difference in the types of microbes present between the sites where SGD occurs versus background (uninfluenced) coastal water, especially in terms of the microbes that consume organic matter. Overall, this study suggests that there is a connection between groundwater and seawater microbes, which can influence the delicate balance between organisms that produce carbon and those that consume it. This has important implications for how carbon cycles globally. Key Points Groundwater discharge into the coastal zone delivers both nutrients and allochthonous microbes Groundwater microbes interact with seawater populations, by which affecting the delicate autotroph‐heterotroph balance Subterranean microbial processes are key drivers of food webs, potentially affecting biogenic carbon fluxes in the ocean
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  • 38
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    Unbekannt
    In:  Zoologische Verhandelingen vol. 279 no. 1, pp. 1-263
    Publikationsdatum: 2024-01-12
    Beschreibung: An index to all names of Odonata mentioned in publications of Maurits Anne Lieftinck (19041985) is provided. Lieftinck mainly published on the Odonata faunas of the Indo-Australian and Palaearctic regions. He revised many genera, described over 600 species and also examined hundreds of primary types of previously described species. He included with his descriptions and revisions accurate line illustrations and carefully composed lists of synonymies and references. The index to his works is therefore a key to nearly the full literature of Indo-Australian Odonata, as well as to valuable museum collections of, especially Indo-Australian, Odonata.
    Schlagwort(e): index ; Odonata ; Malesia ; Australia ; Palaearctic ; bibliography ; Maurits Anne Lieftinck.
    Repository-Name: National Museum of Natural History, Netherlands
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  • 39
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    Unbekannt
    Copernicus GmbH
    In:  EPIC3The Cryosphere, Copernicus GmbH, 15(2), pp. 1131-1156, ISSN: 1994-0416
    Publikationsdatum: 2023-06-21
    Beschreibung: 〈jats:p〉Abstract. A realistic simulation of the surface mass balance (SMB) is essential for simulating past and future ice-sheet changes. As most state-of-the-art Earth system models (ESMs) are not capable of realistically representing processes determining the SMB, most studies of the SMB are limited to observations and regional climate models and cover the last century and near future only. Using transient simulations with the Max Planck Institute ESM in combination with an energy balance model (EBM), we extend previous research and study changes in the SMB and equilibrium line altitude (ELA) for the Northern Hemisphere ice sheets throughout the last deglaciation. The EBM is used to calculate and downscale the SMB onto a higher spatial resolution than the native ESM grid and allows for the resolution of SMB variations due to topographic gradients not resolved by the ESM. An evaluation for historical climate conditions (1980–2010) shows that derived SMBs compare well with SMBs from regional modeling. Throughout the deglaciation, changes in insolation dominate the Greenland SMB. The increase in insolation and associated warming early in the deglaciation result in an ELA and SMB increase. The SMB increase is caused by compensating effects of melt and accumulation: the warming of the atmosphere leads to an increase in melt at low elevations along the ice-sheet margins, while it results in an increase in accumulation at higher levels as a warmer atmosphere precipitates more. After 13 ka, the increase in melt begins to dominate, and the SMB decreases. The decline in Northern Hemisphere summer insolation after 9 ka leads to an increasing SMB and decreasing ELA. Superimposed on these long-term changes are centennial-scale episodes of abrupt SMB and ELA decreases related to slowdowns of the Atlantic meridional overturning circulation (AMOC) that lead to a cooling over most of the Northern Hemisphere. 〈/jats:p〉
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  • 40
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    Unbekannt
    Chicago : Periodicals Archive Online (PAO)
    Economic development and cultural change. 41:4 (1993:July) 875 
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  • 41
    Signatur: Q 2434(16) ; MOP Per 581(1/16) ; ZSP-319/A-16
    In: Geodätische und Geophysikalische Veröffentlichungen : Reihe 1, Heft 16
    In: Antarctic research / edited by H.-J. Paech, D. Fritzsche, Vol. 2
    Materialart: Schriftenreihen ausleihbar
    Seiten: Seiten 281-511 , Illustrationen
    ISSN: 0533-7577
    Serie: Geodätische und Geophysikalische Veröffentlichungen : Reihe 1 16
    Sprache: Englisch
    Anmerkung: Volume II: Glaciology & Periglacial Processes. - Soviet-French cooperation on the isotopic research of cores from Dome B - Vostok - Komsomolskaya - Mirny ice taverse, East Antarctica / C. Lorius ; Ye. S. Korotkevich ; N. I. Barkov ; V. N. Petrov. - On the genesis of the Shackleton Ice Shelf according to oxygen-isotope data / L. Savatyugin; R. Vaikmäe. - G.D.R isotope research in Queen Maud Land (Abstract) / R. Haberlandt. - Isotope data from ice-cored moraines suggest a higher ice sheet surface in Central Queen Maud Land (Antarctica) during cold stages / W.-D. Hermichen ; P. Kowski ; R. Vaikmäe. - An oxygen-18 thermometer from snow of Northern Queen Maud Land / Antarctica / W.-D. Hermichen ; P. Kowski ; R. Vaikmäe. - Initial processes of pedogenesis in the Schirmacher Oasis (Abstract) / W. Krüger ; J. Balke. - Periglacial of Antarctic continent as a source of paleoglacial information / V. I. Bardin. - Sea Ice Analysis. - The major features of ice conditions in the Bellingshausen Sea / V. V. Yevsyeyev. - The duration of the cycle of the Atlantic ice massif existence and typification of the processes causing its isolation / A. M. Kozlovsky. - Hydrology. - The hydrography of the Schirmacher Oasis (Abstract) / W. Richter. - Meteorological and hydrological conditions of meltwater genesis and distribution in Antarctica / A. Loopmann. - Hydrochemical and isotope hydrological investigations in the Bunger Oasis / E. Kaup ; V. Klokov ; R. Vaikmäe ; D. Haendel ; R. Zierath. - Extremely C-13 enriched biomass in a freshwater environment: examples from Antarctic lakes / U. Wand ; K. Mühle. - Biology & Human Biology. - Das Meereis als Lebensraum / G.Hernpel Das biologische Programm "Bellingshausen" - Bericht über die vergangenen 10 Jahre und die Konzeption künftiger Forschungsarbeit / H.Oehme. - Ecological studies in the southern gigant petrel Macronectes giganteus on southwestern parts of King George Island / H.-U. Peter ; M. Kaiser ; A. Gebauer. - Development, torpor and energy balance of black-bellied storm-petrel chicks (Fregatta tropica) (Abstract) / T. Nadler ; H. Mix. - Morphometrical and ecological differences between south polar and brown skuas of Fildes Peninsula, King George Island, South Shetland Islands / H.-U. Peter ; M. Kaiser ; A. Gebauer. - Behavioural biology of the Antarctic tern Sterna vittata (Gmelin, 1789) / A. Gebauer ; M. Kaiser ; H.-U. Peter. - Thermoregulation in the Antarctic tern Sterna vittata (Gmelin, 1789) / M. Kaiser ; A. Gebauer ; H.-U. Peter. - Parasitiological studies in the Antarctic by scientists from the G.D.R / K. Feiler. - New Amphipods from the sublittoral of King George Island - Faunistic contribution to ecological investigations / M. Rauschert. - The freshwater algae of the Schirmacher Oasis - Queen Maud Land / H. Pankow ; D. Haendel ; H. Richter. - The lichens of the Schirmacher Oasis (East Antarctica) / W. Richter. - The bryoflora of the Schirmacher Oasis (East Antarctica) in relations to hydrosphere and cryosphere / W. Richter. - The animals of the Schirmacher Oasis (East Antarctica) / W. Richter ; D. Haendel ; P. Junghans. - Indoor climate and long-time-stays in Arctic and Antarctic regions (Abstract) / W. Bischof ; G. Schrader ; L. Banhidi. - Do psychical factors have an influence on the immunofunction of polar researchers and how could objective evidence be obtained? / F. Wietschel ; G. Schrader.
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    Standort: AWI Lesesaal
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  • 42
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    Springer-Verlag
    In:  EPIC3Berlin, Springer-Verlag, 287 p., ISBN: 3-540-57559-6
    Publikationsdatum: 2021-01-01
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Book , peerRev
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  • 43
    Publikationsdatum: 2024-02-07
    Beschreibung: Key Points: - A new CHBr3 emission inventory based on natural and anthropogenic sources suggests that the latter account for 12%–28% of the global emissions - In the NH, new anthropogenic estimates increase known natural CHBr3 emissions by up to 70.5%, leading to higher atmospheric CHBr3 levels - At the NH extratropical tropopause, CHBr3 is enhanced by 0.9 ppt Br due to anthropogenic sources thus doubling natural CHBr3 abundances Bromoform (CHBr3) contributes to stratospheric ozone depletion but is not regulated under the Montreal Protocol due to its short lifetime and large natural sources. Here, we show that anthropogenic sources contribute significantly to the amount of CHBr3 transported into the Northern Hemisphere (NH) extratropical stratosphere. We present a new CHBr3 emission inventory comprised of natural and anthropogenic sources, with the latter estimated from ship ballast, power plant cooling and desalination plant brine water. Including anthropogenic sources in the new inventory increases CHBr3 emissions by up to 31.5% globally and 70.5% in the NH. In consequence, atmospheric CHBr3 is also significantly higher, especially over the NH extratropics during boreal winter. Here anthropogenic sources enhance bromine at the tropopause by 0.9 ppt Br, thus doubling natural CHBr3 abundances. For some latitudes, tropopause bromine increases by 2.4 ppt Br suggesting significant contributions of anthropogenic CHBr3 to the NH lowermost stratosphere.
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  • 44
    Publikationsdatum: 2023-02-08
    Beschreibung: The control and ban of man-made long-lived ozone-depleting substances (ODSs) by the Montreal Protocol is expected to result in the recovery of the stratospheric ozone layer in the course of the 21st century. However, short-lived ODSs, which belong to the very short-lived substances (VSLSs), are not controlled and also participate in stratospheric ozone depletion through catalytic cycles. VSLSs are produced naturally from macroalgae and phytoplankton, and anthropogenically as disinfection by-products (DBPs) from chemical treatment of industrial water. Chemical treatment of seawater, e.g. cooling water of coastal power plants, mainly produces brominated VSLSs, with bromoform as the major DBP. Bromoform is also the largest source of organic bromine from biological marine sources to the atmosphere. However, the contribution of anthropogenic VSLSs to the global bromine budget is still unclear. Industrial water treatment has increased substantially over the last years due to strong economic growth and progressing industrialisation in East Asia and India. The increasing input of anthropogenic VSLSs from emerging industries to the environment has not been quantified yet. Given the growing importance of brominated VSLSs in the face of declining long-lived ODSs, a quantification of anthropogenic VSLS sources is urgently needed. The aim of this thesis is to quantify the environmental input of anthropogenic brominated VSLSs from industrial water treatment, their distribution in the ocean and atmosphere, and their entrainment into the stratosphere. The assessment focusses on the major DBP bromoform. The global distribution of anthropogenic bromoform sources serves as the initial release field for Lagrangian simulations of bromoform pathways in the ocean and atmosphere, and as the basis for air-sea flux calculations. Oceanic trajectory simulations are performed with the ARIANE software to analyse seasonal to annual variations of bromoform distribution. Atmospheric bromoform mixing ratios are simulated with the FLEXPART model in order to analyse the tropospheric and stratospheric distribution. Combining the climatological bottom-up air sea flux estimate with the bromoform flux from coastal power plants, the global bromine budget increases by 8–35 % to 1.9–2.2 Gmol Br a-1. Over 96 % of treated cooling water originate from the regions East-Southeast Asia, Europe, North America, India and Arabia. Bromoform is usually released close to its oceanic source. An effective transport into the stratosphere mainly takes place in the tropics, whereas in extratropical regions the majority of bromoform stays in the lower troposphere and is rapidly removed by deposition, e.g. in Europe. About half of the global anthropogenic bromoform is released in the region around East-Southeast Asia. The majority of this is discharged in the extratropics along the coasts of the Yellow, Japan and East China Seas. Still about 20 % of the bromoform from this region is entrained into the stratosphere during boreal winter due to transport towards the tropical West Pacific by northeasterly winds. The tropical West Pacific, as well as the Indian Ocean are the most efficient regions for stratospheric entrainment of bromoform. Over the Indian Ocean, tropical convection and the monsoon circulation during boreal summer transport 40–50 % of bromoform from the marine boundary layer to the stratosphere. Thereby, anthropogenic emissions contribute 10–43 % to stratospheric bromoform entrainment over the Indian Ocean, and 4–25 % over the global inner tropics. The anthropogenic sources of brominated VSLSs are predicted to increase in the future. In particular, increased bromoform emissions from growing industries in tropical regions will likely lead to more bromine input into the stratosphere. In order to reduce the uncertainties of DBP concentration in treated seawater, as well as the number of missing sources in the bromoform air-sea flux estimate, additional observations along the coasts close to the industrial areas are necessary. A better understanding of all natural and anthropogenic sources of brominated VSLSs and their future trends will thus improve estimates of the global atmospheric bromine input.
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  • 45
    Publikationsdatum: 2024-02-12
    Beschreibung: Microplastic particles (MPP) occur in various environmental compartments all over the world. They have been frequently investigated in oceans, freshwaters, and sediments, but studying their distribution in space and time is somewhat limited by the time-consuming nature of the available accurate detection strategies. Here, we present an enhanced application of lab-based near-infrared imaging (NIR) spectroscopy to identify the total number of MPP, classify polymer types, and determine particle sizes while maintaining short measuring times. By adding a microscopic lens to the hyperspectral camera and a cross slide table to the setup, the overall detectable particle size has been decreased to 100 µm in diameter. To verify and highlight the capabilities of this enhanced, semi-automated detection strategy, it was applied to key areas of microplastic research, such as a lowland river, the adjacent groundwater wells, and marine beach sediments. Results showed mean microplastic concentrations of 0.65 MPP/L in the Havel River close to Berlin and 0.004 MPP/L in the adjacent groundwater. The majority of MPP detected in the river were PP and PE. In 8 out of 15 groundwater samples, no MPP was found. Considering only the samples with quantifiable MPP, then on average 0.01 MPP/L was present in the groundwater (98.5% removal during bank filtration). The most abundant polymers in groundwater were PE, followed by PVC, PET, and PS. Mean MPP concentrations at two beaches on the German Baltic Sea coast were 5.5~MPP/kg at the natural reserve Heiligensee and Hüttelmoor and 47.5 MPP/kg at the highly frequented Warnemünde beach.
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  • 46
    Online-Ressource
    Online-Ressource
    Cham :Springer International Publishing :
    Schlagwort(e): Human geography. ; Climatology. ; Public health. ; Human physiology. ; Sustainable architecture. ; Buildings Environmental engineering. ; Human Geography. ; Climate Sciences. ; Public Health. ; Human Physiology. ; Sustainable Architecture/Green Buildings. ; Building Physics, HVAC.
    Beschreibung / Inhaltsverzeichnis: Introduction -- Issues in UTCI Calculation from a Decade’s Experience -- Literature Review on UTCI Applications -- Sensitivity of UTCI thermal comfort prediction to personal and situational factors – residual analysis of pedestrian survey data -- Long and short-term acclimatization effects on outdoor thermal perception versus UTCI -- Regional adaptation of the UTCI: Comparisons between different datasets in Brazil -- Outdoor thermal environment and heat-related symptoms of pedestrians: An application of the UTCI for health risk assessment -- Mapping UTCI (in different scales) -- Application of the UTCI in high-resolution urban climate modeling techniques -- The universal thermal climate index as an operational forecasting tool of human biometeorological conditions in Europe -- Proposed framework for establishing a global database for outdoor thermal comfort research -- Afterword.
    Kurzfassung: This book introduces the UTCI (Universal Thermal Climate Index) and summarises progress in this area. The UTCI (Universal Thermal Climate Index) was developed as part of the European COST Action Program and first announced to the scientific community in 2009. Since then a decade has followed of applicability tests and research results as well as knowledge gained from applying the UTCI in human adaptation and thermal perception. These findings are of interest to researchers in the interdisciplinary areas of biometeorology, climatology and urban planning. The book summarizes this progress, discussing the limitations found and provides pointers to future developments. It also discusses UTCI applications in the areas of human biometeorology and urban planning including possibilities of using UTCI and similar indices in climate-responsive urban planning. The book’s message is illustrated with many case studies from the real world. Chapter 10 is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.
    Materialart: Online-Ressource
    Seiten: XII, 228 p. 50 illus., 43 illus. in color. , online resource.
    Ausgabe: 1st ed. 2021.
    ISBN: 9783030767167
    Serie: Biometeorology, 4
    DDC: 304.2
    Sprache: Englisch
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  • 47
    facet.materialart.
    Unbekannt
    Pleiades Publishing Ltd
    In:  EPIC3Izvestiya, Atmospheric and Oceanic Physics, Pleiades Publishing Ltd, 57 (10(10), pp. 1254-1270, ISSN: 0001-4338
    Publikationsdatum: 2024-04-19
    Beschreibung: The archaeal composition of permafrost samples taken during the drilling of frozen marine sediments in the area of the Barentsburg coal mine on the east coast of Grønfjord Bay of Western Spitsbergen has been studied. This study is based on an analysis of the V4 region of the 16S rRNA gene, carried out using next-generation sequencing. The general phyla of the Archaea domain are Euryarchaeota, Bathyarchaeota, Thaumarchaeota, and Asgardarchaea. As a result of a phylogenetic analysis of the dominant operational taxonomic units, representatives of methanogenic and methane- and ammonium-oxidizing archaea, as well as heterotrophic archaea, are found. The methanogenic archaea of Euryarchaeota phylum, Methanobacteria class, are found in permafrost with controversial genesis, while the methane-oxidizing archaea of Methanomicrobia class Methanosarcinales order are found in the marine permafrost at Cape Finneset: the ANME-2a, -2b group in layers of 8.6 and 11.7 m and the ANME-2d group (Candidatus Methanoperedens) in a layer of 6.5 m. Ammonium-oxidizing archaea of phylum Thaumarchaeota is present in all types of permafrost, while the order of Nitrososphaerales is found in permafrost with controversial genesis and the order Nitrosopumilales is in permafrost with marine and controversial genesis. Representatives of phylum Bathyarchaeota are found stratigraphically in the most ancient samples under study. Asgardarchaeota superfylum is excluded in the layers of permafrost with marine genesis and is represented by the phyla Lokiarchaeota, Thorarchaeota, and an unclassified group belonging to this superphylum. The presence of methane, ethylene, and ethane in the permafrost of the first sea terrace of Cape Finneset at a depth of 11.7 m, as well as the composition of the archaeal community, give us reason to assume that, before freezing, microbiological processes of anaerobic methane oxidation took place in it, probably received from Tertiary rocks. The results of both this and previous works present the Spitsbergen permafrost as a rich archive of genetic information of little-studied prokaryotic groups.
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  • 48
    facet.materialart.
    Unbekannt
    Russian Academy of Science
    In:  EPIC3Geofizicheskie Protsessy i Biosfera (Geophysical Processes and Biosphere), Russian Academy of Science, 20(3), pp. 20-38, ISSN: 1811-0045, 2311-9578
    Publikationsdatum: 2024-04-20
    Beschreibung: The archaeal composition of permafrost samples taken during drilling of frozen marine sediments in the area of the Barentsburg coal mine on the east coast of Grønfjord Bay of Western Spitsbergen has been studied. The study was based on the analysis of the V4 region of the 16S rRNA gene, carried out using next generation sequencing. This is the second part of the work dedicated to the prokaryotic composition of the Western Spitsbergen, the fi rst part was devoted to the domain of Bacteria. The general phyla of the the Archaea domain were Euryarchaeota, Bathyarchaeota, Thaumarchaeota and Asgardarchaeota. As a result of phylogenetic analysis of the dominant operational taxonomic units, representatives of methanogenic methane- and ammonium-oxidizing archaea, as well as heterotrophic archaea were found. Methanobacteria class of methanogenic archaea was found in the controversial genesis, while methane-oxidizing archaea of the Methanomicrobia class of Methanosarcinales order were found in the marine permafrost of Cape Finneset: ANME-2a, -2b group was found in layers 8.6 and 11.7 m, and a group ANME-2d (Candidatus Methanoperedens) – in a layer of 6.5 m. Ammonium-oxidizing archaea of the phylum Thaumarchaeota was present in all types of permafrost, while Nitrososphaerales was detected in controversial genesis permafrost, and the order-Nitrosopumilales in the marine permafrost or controversial genesis ones. Representatives of phylum Bathyarchaeota were found in the stratigraphicly most ancient samples under this study. Superphylum Asgardarchaeota was met exclusively in the layers of permafrost with marine genesis and was represented by phyla Lokiarchaeota, Thorarchaeota and another group belonging to this superphylum that was not identified by us. The presence in the marine permafrost terrace of Cape Finneset at 11.7 m depth of methane, ethylene and ethane, as well as the composition of the archaeal community gives this layer to assume in it the presence of microbiological processes of the anaerobic oxidation of methane, probably received from Tertiary deposits before freezing. The results obtained are represented the permafrost of Spitsbergen as a rich archive of genetic information of little studied prokaryotic groups.
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  • 49
    Publikationsdatum: 2023-02-08
    Beschreibung: A compilation of the published literature on dust content in terrestrial and marine sediment cores was synchronized with pollen data and speleothem growth phases on the Greenland Ice Core Chronology 2005 (GICC05) time axis. Aridity patterns for eight key areas of the global climate system have been reconstructed for the last 60 000 years. These records have different time resolutions and different dating methods, i.e. different types of stratigraphy. Nevertheless, all regions analysed in this study show humid conditions during early Marine Isotope Stage 3 (MIS3) and the early Holocene or deglaciation, but not always at the same time. Such discrepancies have been interpreted as regional effects, although stratigraphic uncertainties may affect some of the proposed interpretations. In comparison, most of the MIS2 interval becomes arid in all of the Northern Hemisphere records, but the peak arid conditions of the Last Glacial Maximum (LGM) and Heinrich event 1 differ in duration and intensity among regions. In addition, we also compare the aridity synthesis with modelling results using a global climate model (GCM). Indeed, geological archives and GCMs show agreement on the aridity pattern for the Holocene or deglaciation, for the LGM and for late MIS3.
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  • 50
    Publikationsdatum: 2024-02-07
    Beschreibung: The Eastern Tropical South Pacific (ETSP), hosts an extensive Oxygen Minimum Zone (OMZ) in the water column which has a major imprint on local and global marine biogeochemistry. Due to the low oxygen conditions within the OMZ, microbial processes of nitrogen (N) loss, such as anammox and denitrification are sustained in the water column. These processes result in a pronounced N deficit which reduces bioavailable N for primary productivity and thus influences fisheries production in the region. To maintain a balanced marine N inventory regionally in ETSP, the N deficit would have to be compensated by N inputs via upwelling or N2 fixation. A classical assumption is that N2 fixation is favoured by iron (Fe) availability and a surplus of inorganic phosphate relative to inorganic nitrogen (this relativity is defined as P*), both conditions are present in the ETSP. Over the past decades, this assumption has been integrated into most coupled circulation and N-cycle biogeochemical models. These models indicate that there is a close spatial link between areas of high N loss, generally confined to OMZs and N2 fixation. On the contrary, other biogeochemical models have revealed that a close spatial link between N loss and N2 fixation in OMZ areas may give rise to run-away loss of fixed N in the ETSP, ultimately destabilizing the regional marine N inventory. While N loss processes are relatively well understood in the ETSP, the lack of a comprehensive dataset that resolves N2 fixation rates in both space and time constraints an accurate assessment of the regional marine N inventory, potential feedback mechanisms, and their impact on N turnover and productivity. Therefore, the main objective of this doctoral dissertation was to investigate the spatial distribution of N2 fixation relative to N loss in the ETSP, in order to understand potential feedbacks in the regional N cycle.
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  • 51
    Publikationsdatum: 2024-04-05
    Beschreibung: We examine the impact of horizontal resolution and model time step on the climate of the OpenIFS version 43r3 atmospheric general circulation model. A series of simulations for the period 1979–2019 are conducted with various horizontal resolutions (i.e. ∼100, ∼50, and ∼25 km) while maintaining the same time step (i.e. 15 min) and using different time steps (i.e. 60, 30, and 15 min) at 100 km horizontal resolution. We find that the surface zonal wind bias is significantly reduced over certain regions such as the Southern Ocean and the Northern Hemisphere mid-latitudes and in tropical and subtropical regions at a high horizontal resolution (i.e. ∼25 km). Similar improvement is evident too when using a coarse-resolution model (∼100 km) with a smaller time step (i.e. 30 and 15 min). We also find improvements in Rossby wave amplitude and phase speed, as well as in weather regime patterns, when a smaller time step or higher horizontal resolution is used. The improvement in the wind bias when using the shorter time step is mostly due to an increase in shallow and mid-level convection that enhances vertical mixing in the lower troposphere. The enhanced mixing allows frictional effects to influence a deeper layer and reduces wind and wind speed throughout the troposphere. However, precipitation biases generally increase with higher horizontal resolutions or smaller time steps, whereas the surface air temperature bias exhibits a small improvement over North America and the eastern Eurasian continent. We argue that the bias improvement in the highest-horizontal-resolution (i.e. ∼25 km) configuration benefits from a combination of both the enhanced horizontal resolution and the shorter time step. In summary, we demonstrate that, by reducing the time step in the coarse-resolution (∼100 km) OpenIFS model, one can alleviate some climate biases at a lower cost than by increasing the horizontal resolution.
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  • 52
    Publikationsdatum: 1994-01-01
    Print ISSN: 0380-1330
    Thema: Biologie
    Publiziert von Elsevier
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  • 53
    Publikationsdatum: 2024-05-31
    Beschreibung: To better understand possible reasons for the diverse modeling results and large discrepancies of the detected solar fingerprints, we took one step back and assessed the "initial" solar signals in the middle atmosphere based on large ensemble simulations with multiple climate models — FOCI, EMAC, and MPI-ESM-HR. Consistent with previous work, we find that the 11-year solar cycle signals in the short wave heating rate (SWHR) and ozone anomalies are robust and statistically significant in all three models. These "initial" solar cycle signals in SWHR, ozone, and temperature anomalies are sensitive to the strength of the solar forcing. Correlation coefficients of the solar cycle with the SWHR, ozone, and temperature anomalies linearly increase along with the enhancement of the solar cycle amplitude, and this reliance becomes more complex when the solar cycle amplitude exceeds a certain threshold. In addition, the cold bias in the tropical stratopause of EMAC dampens the subsequent results of the "initial" solar signal. The warm pole bias in MPI-ESM-HR leads to a weak polar night jet (PNJ), which may limit the top-down propagation of the initial solar signal. Although FOCI simulated a so-called top-down response as revealed in previous studies in a period with large solar cycle amplitudes, its warm bias in the tropical upper stratosphere results in a positive bias in PNJ and can lead to a "reversed" response in some extreme cases. We suggest a careful interpretation of the single model result and further re-examination of the solar signal based on more climate models.
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  • 54
    facet.materialart.
    Unbekannt
    Springer VS
    In:  Studien zur Migrations- und Integrationspolitik
    Publikationsdatum: 2023-10-19
    Beschreibung: This open access book examines how and why various forms of climate (im)mobilities can impact people's objective and subjective well-being. Worsening climate impacts are forcing subsistence farmers worldwide to decide between staying or leaving their homes. This mixed methods study analyzes cases of climate-related migration, displacement, relocation, and immobility in Peru's coastal, highland, and rainforest regions. The results reveal that numerous farmers experienced profound and often negative well-being impacts, regardless of whether they stayed or migrated. The higher the structural constraints, such as weak governance, and the more damaging the climate impacts were, the higher the risk of well-being declines. Additionally, the affected individuals often had limited agency and ability to mitigate losses. These findings challenge the notion of "migration as adaptation" and emphasize the importance of safeguarding the human rights and security of those affected while addressing loss and damage. Without significant investments in such efforts, climate impacts could sharply diminish the well-being of numerous subsistence farmers worldwide—irrespective of whether they stay or migrate.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/book
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  • 55
    Publikationsdatum: 2024-02-07
    Beschreibung: Foraging is a behavioural process and, therefore, individual behaviour and diet are theorized to covary. However, few comparisons of individual behaviour type and diet exist in the wild. We tested whether behaviour type and diet covary in a protected population of Atlantic cod, Gadus morhua. Working in a no-take marine reserve, we could collect data on natural behavioural variation and diet choice with minimal anthropogenic disturbance. We inferred behaviour using acoustic telemetry and diet from stable isotope compositions (expressed as δ13C and δ15N values). We further investigated whether behaviour and diet could have survival costs. We found cod with shorter diel vertical migration distances fed at higher trophic levels. Cod δ13C and δ15N values scaled positively with body size. Neither behaviour nor diet predicted survival, indicating phenotypic diversity is maintained without survival costs for cod in a protected ecosystem. The links between diet and diel vertical migration highlight that future work is needed to understand whether the shifts in this behaviour during environmental change (e.g. fishing or climate), could lead to trophic cascades.
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  • 56
    Publikationsdatum: 2024-02-07
    Beschreibung: The Indian Ocean is coupled to atmospheric dynamics and chemical composition via several unique mechanisms, such as the seasonally varying monsoon circulation. During the winter monsoon season, high pollution levels are regularly observed over the entire northern Indian Ocean, while during the summer monsoon, clean air dominates the atmospheric composition, leading to distinct chemical regimes. The changing atmospheric composition over the Indian Ocean can interact with oceanic biogeochemical cycles and impact marine ecosystems, resulting in potential climate feedbacks. Here, we review current progress in detecting and understanding atmospheric gas-phase composition over the Indian Ocean and its local and global impacts. The review considers results from recent Indian Ocean ship campaigns, satellite measurements, station data, and information on continental and oceanic trace gas emissions. The distribution of all major pollutants and greenhouse gases shows pronounced differences between the landmass source regions and the Indian Ocean, with strong gradients over the coastal areas. Surface pollution and ozone are highest during the winter monsoon over the Bay of Bengal and the Arabian Sea coastal waters due to air mass advection from the Indo-Gangetic Plain and continental outflow from Southeast Asia. We observe, however, that unusual types of wind patterns can lead to pronounced deviations of the typical trace gas distributions. For example, the ozone distribution maxima shift to different regions under wind scenarios that differ from the regular seasonal transport patterns. The distribution of greenhouse gases over the Indian Ocean shows many similarities when compared to the pollution fields, but also some differences of the latitudinal and seasonal variations resulting from their long lifetimes and biogenic sources. Mixing ratios of greenhouse gases such as methane show positive trends over the Indian Ocean, but long-term changes in pollution and ozone due to changing emissions and transport patterns require further investigation. Although we know that changing atmospheric composition and perturbations within the Indian Ocean affect each other, the impacts of atmospheric pollution on oceanic biogeochemistry and trace gas cycling are severely understudied. We highlight potential mechanisms, future research topics, and observational requirements that need to be explored in order to fully understand such interactions and feedbacks in the Indian Ocean region.
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  • 57
    Publikationsdatum: 2023-02-14
    Beschreibung: The microbiota of multicellular organisms undergoes considerable changes during development but the general mechanisms that control community assembly and succession are poorly understood. Here, we use bacterial recolonization experiments in Nematostella vectensis as a model to understand general mechanisms determining bacterial establishment and succession. We compared the dynamic establishment of the microbiome on the germfree host and on inert silica. Following the dynamic reconstruction of microbial communities on both substrates, we show that the initial colonization events are strongly influenced by the host but not by the tube, while the subsequent bacteria-bacteria interactions are the main cause of bacterial succession. Interestingly, the recolonization pattern on adult hosts resembles the ontogenetic colonization succession. This process occurs independently of the bacterial composition of the inoculum and can be followed at the level of individual bacteria, suggesting that priority effects are neglectable for early colonization events in Nematostella . To identify potential metabolic traits associated with initial colonization success and potential metabolic interactions among bacteria associated with bacterial succession, we reconstructed the metabolic networks of bacterial colonizers based on their genomes. These analyses revealed that bacterial metabolic capabilities reflect the recolonization pattern, and the degradation of chitin might be a selection factor during early colonization of the animal. Concurrently, transcriptomic analyses revealed that Nematostella possesses two chitin synthase genes, one of which is upregulated during early recolonization. Our results show that early colonization events are strongly controlled by the host while subsequent colonization depends on metabolic bacteria-bacteria interactions largely independent of host development.
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  • 58
    Publikationsdatum: 2024-01-09
    Beschreibung: An earthquake sequence in western Canada exhibits resurgent aftershocks, possibly in response to persistent, post-mainshock saltwater disposal. Here, we reduce uncertainty in mainshock source parameters with joint inference of interferometric synthetic aperture radar and seismic waveform data, showing that the mainshock nucleated at about 5-km depth, propagating up-dip toward the injection source, and arresting at about 2-km depth. With precise hypocenter relocations and Bayesian inference, we reveal that four subparallel faults were reactivated, likely part of a regional, basement-rooted graben system. The reactivated faults appear to be truncated by a conjugate fault that is misoriented for slip in the present-day stress regime. The nearest saltwater disposal well targets a permeable Devonian reef in direct contact with Precambrian basement, atop a ridge-like uplift. Our observations show that a fault system can be activated more than a decade after saltwater disposal initiation, and continued disposal may lead to a resurgence of seismicity.
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  • 59
    facet.materialart.
    Unbekannt
    In:  Journal of Geophysical Research: Solid Earth
    Publikationsdatum: 2023-05-24
    Beschreibung: The main sources of the ambient seismic wavefield in the microseismic frequency band (peaking in the ∼0.04–0.5 Hz range) are earth's oceans, namely the wind-driven surface gravity waves (SGW) that couple oscillations into the seafloor and the upper crust underneath. Cyclones (e.g., hurricanes, typhoons) and other atmospheric storms are efficient generators of high ocean waves that in turn generate distinct microseismic signatures. In this study, we perform a polarization (i.e., three-component) beamforming analysis of microseismic (0.05–0.16 Hz) retrograde Rayleigh and Love waves during major Atlantic hurricanes using a virtual array of seismometers in Eastern Canada. Oceanic hindcasts and meteorological data are used for comparison. No continuous generation of microseism along the hurricane track is observed but rather an intermittent signal generation. Both seismic surface wave types show clear cyclone-related microseismic signatures that are consistent with a colocated generation at near-coastal or shallow regions, however the Love wavefield is comparatively less coherent. We identify two different kinds of intermittent signals: (a) azimuthally progressive signals that originate with a nearly constant spatial lag pointing toward the trail of the hurricanes and (b) azimuthally steady signals remaining nearly constant in direction of arrival even days after the hurricane significantly changed its azimuth. This high complexity highlights the need for further studies to unravel the interplay between site-dependent geophysical parameters, SGW forcing at depth and microseismic wavefield radiation and propagation, as well as the potential use of cyclone microseisms as passive natural sources.
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  • 60
    Publikationsdatum: 2023-12-16
    Beschreibung: Microbial composition and diversity in marine sediments are shaped by environmental, biological, and anthropogenic processes operating at different scales. However, our understanding of benthic microbial biogeography remains limited. Here, we used 16S rDNA amplicon sequencing to characterize benthic microbiota in the North Sea from the top centimeter of 339 sediment samples. We utilized spatially explicit statistical models, to disentangle the effects of the different predictors, including bottom trawling intensity, a prevalent industrial fishing practice which heavily impacts benthic ecosystems. Fitted models demonstrate how the geographic interplay of different environmental and anthropogenic drivers shapes the diversity, structure and potential metabolism of benthic microbial communities. Sediment properties were the primary determinants, with diversity increasing with sediment permeability but also with mud content, highlighting different underlying processes. Additionally, diversity and structure varied with total organic matter content, temperature, bottom shear stress and bottom trawling. Changes in diversity associated with bottom trawling intensity were accompanied by shifts in predicted energy metabolism. Specifically, with increasing trawling intensity, we observed a transition toward more aerobic heterotrophic and less denitrifying predicted metabolism. Our findings provide first insights into benthic microbial biogeographic patterns on a large spatial scale and illustrate how anthropogenic activity such as bottom trawling may influence the distribution and abundances of microbes and potential metabolism at macroecological scales.
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  • 61
    Publikationsdatum: 2024-02-07
    Beschreibung: Barium (Ba) isotopes are a promising new tracer for riverine freshwater input to the ocean and marine biogeochemical cycling. However, many processes that affect Ba cycling at continental margins have not yet been investigated with respect to Ba isotope fractionation. Here, we present a comprehensive data set of Ba concentration and isotope data for water column, pore water and sediment samples from Kiel Bight, a seasonally stratified and hypoxic fjord in the southwestern Baltic Sea. The surface water Ba concentration and Ba isotope inventory of the water column can generally be explained by mixing of riverine freshwater and Atlantic seawater. However, the deep-water below the seasonal pycnocline (10 - 15 m water depth) is characterized by a pronounced positive Ba concentration anomaly (up to 915 nM) that is accompanied by a δ138Ba of ~+0.25 ‰, which is lighter than expected from the seawater-freshwater mixing line (Ba: 77 nM, δ138Ba: +0.32 ‰ at a salinity of 18). Pore water profiles indicate a Ba flux across the sediment-water interface, which contributes to the enrichment in isotopically light Ba in the deep-water. Pore waters of surface sediments and deep-waters are oversaturated with respect to barite. Therefore, barite dissolution is unlikely to account for the benthic Ba flux. Water column Ba concentrations closely correlate with those of the nutrients phosphate and silica, which are removed from surface waters by biological processes and recycled from the sediment by diffusion across the sediment-water interface. As nutrient-to-Ba ratios differ among sites and from those observed in open-marine systems, we propose that Ba is removed from surface waters by adsorption onto biogenic particles (rather than assimilation) and regenerated within surface sediments upon organic matter degradation. Pore water data for subsurface sediments in Kiel Bight indicate preferential transfer of isotopically heavy Ba into an authigenic phase during early diagenesis. Quantifying the burial flux associated with this authigenic Ba phase along continental margins could potentially help to settle the isotopic imbalance between known Ba source and sink fluxes in the ocean.
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  • 62
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Kyklos 46 (1993), S. 0 
    ISSN: 1467-6435
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Sociologie , Wirtschaftswissenschaften
    Notizen: Acs, ZOLTAN J. and AUDRETSCH, DAVID B. (eds.): Small Firms and Entrepreneurship: An East-West PerspectiveBATES, ROBERT H. and KRUEGER, ANNE O. (eds.): Political and Economic Interactions in Economic Policy ReformBIRD, RICHARD M. and DE JANTSCHER, MILU C. (eds.): Improving Tax Administration in Developing CountriesBOLAND, LAWRENCE A.: The Principles of EconomicsCOUGHLIN, PETER J.: Probabilistic Voting TheoryDIETZ, FRANK J.; SIMONIS, UDo E. and VAN DER STRAATEN, JAN (eds.): Sustainability and Environmental PolicyGEROSKI, P. A.: Market Dynamics and EntryHARGREAVES HEAP, SHAUN P.: The New Keynesian MacroeconomicsHAY, D. A. and MORRIS, D. J.: Industrial Economics and Organization: Theory and EvidenceISLAM, SHAFIQUL and MANDELBAUM, MICHAEL (eds.): Making MarketsJAEGER, FRANZ: Natur und WirtschaftMAYER, THOMAS: Truth Versus Precision in Economics. Advances in Economic Methodology Series, AldershotMILLER, GARY J.: Manageral DilemsMORISHIMA, MICHIO: Capital & CreditPEARCE, ROBERT D.: The Crowth and Evolution of Multinational EnterprisePOLACHEK, SOLOMON W. and SIEBERT, W. STANLEY: The Economics of EarningsPRESLEY, JOHN R. (ed.): Essays on Robertsonian EconomicsREID, GAVIN C.: Small Business EnterpriseROTHSCHILD, KURT W.: Ethics and Economic Theory: Ideas - Models - DilemmasSALVATORE, DOMINICK: International EconomicsSMITH, VERNON L.: Papers in Experimental EconomicsTALKENBERG, ANDREA: Die Ökonomie des BildermarktesTEUTEMANN, MANFRED: Rationale Kompetenzverteilung im Rahmen der europäischen IntegrationTYERS, ROGER and ANDERSON, KYM: Disarray in World Food MarketsWAGENER, HANS-JÜRGEN (Hg.): Anpassung durch WandelMYRDAL, GUNNAR: The Political Element in the Development of Economic TheoryMACKENROTH, GERHARD: Theoretische Grundlagen der Preisbildungsforschung und PreisbildungspolitikCHIPMAN, J. S.: ‘A Survey of the Theory of International Trade: Part 1: The Classical Theory, EconometricaGORDON, ROBERT J.: ‘What is New-Keynesian Economics?’. Journal of Economic LiteratureHOLMSTROM, BENGT: ‘Mod Hazard in Teams’, Bell Journal of EconomicsWHYTE, WILLIAM: Money and Motivation: An Analysis of Incentives in IndustryKEYNES. JOHN: ‘Alfred Marshall, 1842-1924’, Economic JournalLOVEMAN, GARY and SENCENBERGER, WERNER: ‘The Re-emergence of Small-Scale Production: An International Comparison’, Small Business EconomicsBROADWAY. R. and BRUCE, N.: Welfare EconomicsHAMMOND, P. J.: Dual Interpersonal Comparisons of Utility and the Welfare Economics of Income Distribution', Journal of public EconomicsSEN, A. K.: Collective Choice and Social WelfareSEN, A. K.: ‘Social Choice Theory: A Re-examination’, EconometricaSEN, A. K.: ‘Personal Utilities and Public Judgements: Or What's Wrong with Welfare Economics?’, Economic JournalSEN, A. K.: Choice, Welfare and MeasurementSEN, A. K.: ‘The Moral Standing of Markets’, Social Philosophy and PolicySEN, A. K. and WILLIAMS, B.: Utilitarism and BeyondADAM, JAN: Planning and Market in Soviet and East European Thought, 1960s-1992ALLAIS, MAURICE: Les Fondements Comptables de la Macro-économiqueALIEN, SHEILA and TRUMAN, CAROLE (eds.): Women in BusinessATKINSON, ANTHONY B. (ed.): Alternatives to CapitalismBALASSA, BELA: Policy Choices for the 1990sBERGSTEN, C. FRED and NOLAND, MARCUS (eds.): Pacific Dynamism and the International Economic SystemBEROSTEN, C. FRED and NOLAND, MARCUS: Reconcilable Differences?BOULDING, KENNETH E.: The Structure of a Modern EconomyBOWLES, SAMUEL; GINTIS, HERBERT and GUSTAFSSON, Bo (eds.): Markets and Democracy: Participation, Accountability and EfficiencyBRUNSSON, NILS and OLSEN, JOHAN P.: The Reforming OrganizationBUBCHTEMANN, CHRISTOPH F. (ed.): Employment Security and Labor Market BehaviorBUTTON, KENNETH J.: Transport EconomicsCAIRNCROSS, ALEC: Austin RobinsonCIBORRA, CLAUDIO U.: Teams, Markets and SystemsCLARKE, THOMAS and PITELIS, CHRISTOS (eds.): The Political Economy of PrivatizationCURRIE, DAVID and LEVTNE, PAUL: Rules, Reputation and Macroeconomic Policy CoordinationDASGUPTA, AJIT: A History of Indian Economic ThoughtVAN DAAL, JAN and JOLINK, ALBERT: The Equlibrium Economics of Léon WalrasVAN DEN DOEL, HANS and VAN VELTHOVEN, BEN: Democracy and Welfare EconomicsDOMINGUEZ, KATHRYN M. and FRANKEL, JEFFREY A.: Does Foreign Exchange Intervention Work? Washington, D. CDOWD, KEVIN: Laissez-faire BankingDRÈZE, JACQUES H.: Underemployment EquilibriaETHIER, WILFRED J.; HELPMAN, ELHANAN and NEARY, J. PETER (eds.): Theory, Policy and Dynamics in International TradeFAINI, RICCARDO and DE MELO, JAIME (eds.): Fiscal Issues in Adjustment in Developing CountriesFISCHER, JÜRGEN; MESSNER, FRANK und WOHLMUTH, KARL (Hrsg.): Die Transformation der osteuropäischen Länder in die MarktwirtschaftFRISCH, HELMUT and WÖRGÖTTER, ANDREAS (eds.): Open-Economy MacroeconomicsFURNHAM, ADRIAN and GUNTER, BARRIE: Corporate AssessmentGOMES, LEONARD: The International Adjustment MechanismGREENAWAY, DAVID and MILNER, CHRIS: Trade and Industrial Policy in Developing CountriesGRINSPUN, RICARDO and CAMERON, MAXWELL A. (eds.): The Political Economy of North American Free TradeGUNTER, BARRIE; FURNHAM, ADRIAN and DRAKELY, RUSSELL: BiodataHABERLER, GOTTFRIED: The Liberal Economic OrderHABERLER, GOTTFRIED: The Liberal Economic OrderHARTSHORN, J. E.: Oil TradeHERR, HANSJÖRG und WESTPHAL, ANDREAS (Hrsg.): Transformation in Mittel- und OsteuropaHERRMANN, ROLAND; BURGER. KEES and SMTP, HIDDE P.: International Commodity PolicyHOLZMANN, ROBERT und NECX, REINHARD (Hrsg.): Konjunktureffekte der österreichischen BudgetpolitikIANNELLO, KATHLEEN P.: Decisions Without HierarchyJERGER, JÜRGEN: Beschäftigung und KapitalbildungJOHANSSON, PER-OLOV: Cost-Benefit Analysis of Environmental ChangeKECK, OTTO: Information, Macht und gesellschaftliche RationalitätKLEINKNECHT, ALFRED and BAIN, DONALD (eds.): New Concepts in Innovation Output MeasurementKNOESTER, ANTHONIE (ed.): Taxation in the United States and EuropeLAUNHARDT, WILHELM: Mathematical Principles of EconomicsLEE, FREDERIC S. and EARL, PETER E. (eds.): The Economics of Competitive EnterpriseLINDBBCX, ASSAR: Unemployment and MicroeconomicsLONDERO, ELIO (ed.): Precios de cuentaLOW, PATRICK: Trading Free: The Gatt and the US Trade PolicyMARTIN, STEPHEN: Advanced Industrial EconomicsMAYES, DAVID; HACER, WOLFGANG; KNIGHT, ARTHUR and STREECK, WOLFGANG: Public Interest and Market PressuresDE MELO, JAIME and PANAGARIYA, JAIME (eds.): New Dimensions in Regional IntegrationMEUWLY, DANIELLE: La convertibilité de roubleMICHABLIS, PETER: Ökonomische Aspekte der AbfallgesetzgebungMUELLER, DENNIS C: The Public Choice Approach to PoliticsMUNASINGHR, MOHAN and MEIER, PETER: Energy Policy Analysis and ModelingMUÑOZ, HERALDO and ROSENBERG, ROBIN (eds.): Difficult Liaison: Trade and the Environment in the AmericasOYE, KENNETH A.: Economic Discrimination and Political ExchangeVAN PARUS, PHILIPPE: Marxism RecycledPERELMAN, MICHAEL: The Pathology of the U. S. EconomyRHOADS, STEVEN E.: Incomparable WorthSAUNDERS, CHRISTOPHER T. (ed.): The Role of Competition in Economic TransitionSCOTT, JOHN T.: Purposive Diversification and Economic PerformanceSCHULTZ, THEODORE W.: The Economics of Being PoorSIEBERT, HORST (Hrsg.): Die zweifache Integration: Deutschland und EuropaSIEBERT, HORST (ed.): Economic Growth in the World EconomySINGLETON, KENNETH J. (ed.): Japanese Monetary PolicySPAHN, PAUL B.: The Community Budget for an Economic and Monetary UnionSPASH, CLIVE L. and HANLEY, NICK: Cost-Benefit Analysis and the EnvironmentSTEELE, G. R.: The Economics of Friedrich HayekSZENBERG, MICHAEL (ed.): Eminent EconomistsTAKAGI, SHIN (ed.): Japanese Capital MarketsTERANISHI, JURO and KOSAI, YUTAKA (eds.): The Japanese Experience of Economic ReformsTHOMPSON, GRAHAME F.: The Economic Emergence of a New Europe?THOMPSON, NEII: Portfolio Theory and the Demand for MoneyTHOMSON, ROSS (ed.): Learning and Technological ChangeUnited Nations: The Control and Management of Government Expenditure: Issues and Experience in Asian CountriesWACHITER, DANIEL: BodenmarktpolitikWA
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  • 63
    Publikationsdatum: 2023-09-20
    Beschreibung: Integrated assessment models (IAMs) are a central tool for the quantitative analysis of climate change mitigation strategies. However, due to their global, cross-sectoral and centennial scope, IAMs cannot explicitly represent the temporal and spatial details required to properly analyze the key role of variable renewable energy (VRE) in decarbonizing the power sector and enabling emission reductions through end-use electrification. In contrast, power sector models (PSMs) can incorporate high spatiotemporal resolutions but tend to have narrower sectoral and geographic scopes and shorter time horizons. To overcome these limitations, here we present a novel methodology: an iterative and fully automated soft-coupling framework that combines the strengths of a long-term IAM and a detailed PSM. The key innovation is that the framework uses the market values of power generations and the capture prices of demand flexibilities in the PSM as price signals that change the capacity and power mix of the IAM. Hence, both models make endogenous investment decisions, leading to a joint solution. We apply the method to Germany in a proof-of-concept study using the IAM REgional Model of INvestments and Development (REMIND) v3.0.0 and the PSM Dispatch and Investment Evaluation Tool with Endogenous Renewables (DIETER) v1.0.2 and confirm the theoretical prediction of almost-full convergence in terms of both decision variables and (shadow) prices. At the end of the iterative process, the absolute model difference between the generation shares of any generator type for any year is 〈 5 % for a simple configuration (no storage, no flexible demand) under a “proof-of-concept” baseline scenario and 6 %–7 % for a more realistic and detailed configuration (with storage and flexible demand). For the simple configuration, we mathematically show that this coupling scheme corresponds uniquely to an iterative mapping of the Lagrangians of two power sector optimization problems of different time resolutions, which can lead to a comprehensive model convergence of both decision variables and (shadow) prices. The remaining differences in the two models can be explained by a slight mismatch between the standing capacities in the real world and optimal modeling solutions based purely on cost competition. Since our approach is based on fundamental economic principles, it is also applicable to other IAM–PSM pairs.
    Sprache: Englisch
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  • 64
    Publikationsdatum: 2023-02-08
    Beschreibung: A site at the gas hydrate stability limit was investigated offshore northwestern Svalbard to study methane transport in sediment. The site was characterized by chemosynthetic communities (sulfur bacteria mats, tubeworms) and gas venting. Sediments were sampled with in‐situ porewater collectors and by gravity coring followed by analyses of porewater constituents, sediment and carbonate geochemistry, and microbial activity, taxonomy, and lipid biomarkers. Sulfide and alkalinity concentrations showed concentration maxima in near‐surface sediments at the bacterial mat and deeper maxima at the gas vent site. Sediments at the periphery of the chemosynthetic field were characterized by two sulfate‐methane transition zones (SMTZ) at ~204 and 45 cm depth, where activity maxima of microbial anaerobic oxidation of methane (AOM) with sulfate were found. Amplicon sequencing and lipid biomarker indicate that AOM at the SMTZs was mediated by ANME‐1 archaea. A 1D numerical transport reaction model suggests that the deeper SMTZ‐1 formed on centennial scale by vertical advection of methane, while the shallower SMTZ‐2 could only be reproduced by non‐vertical methane injections starting on decadal scale. Model results were supported by age distribution of authigenic carbonates, showing youngest carbonates within SMTZ‐2. We propose that non‐vertical methane injection was induced by increasing blockage of vertical transport or formation of sediment fractures. Our study further suggests that the methanotrophic response to the non‐vertical methane injection was commensurate with new methane supply. This finding provides new information about for the response time and efficiency of the benthic methane filter in environments with fluctuating methane transport.
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  • 65
    Publikationsdatum: 2024-05-08
    Beschreibung: During the cruise POS432 on board the German R/V Poseidon, we collected water with a CTD SBE 11plus equipped with 14 Hydrobios free flow bottles of 10 L each in 15 stations (resulting in almost 100 samples) in the Madeira basin region, Northeast Atlantic. We aimed to study the physical and biogeochemical conditions of the water column along the 22°W meridian, north and south of the Azores Front, in May 2012. We measured concentrations of chlorophyll a, phaeopigments, suspended particulate material (SPM), and nutrients such as nitrate, nitrite, phosphate, and silicate.
    Schlagwort(e): Azores Front; biogeochemistry; Chlorophyll a; CTD, Sea-Bird, SBE 911plus; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH, water; ELEVATION; Event label; fluorometer (ethanol extraction; GF/F-filtered) (Grasshoff et al., 1999); gravimetrically (GF/F-filtered) (Grasshoff et al., 1999); Longitude of event; Nitrate; Nitrite; Northeast Atlantic; Phaeopigments; Phosphate; POS432; POS432_118-2; POS432_119-1; POS432_120-1; POS432_121-1; POS432_124-1; POS432_125-1; POS432_126-3; POS432_128-1; POS432_129-1; POS432_131-1; POS432_132-1; POS432_133-1; POS432_136-1; POS432_137-1; POS432_138-1; Poseidon; Salinity; Silicate; Suspended particulate matter; Temperature, water; Water volume, filtered; wet chemical treatment; Continuous flow analysis (Grasshoff et al., 1999)
    Materialart: Dataset
    Format: text/tab-separated-values, 1020 data points
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  • 66
    ISSN: 0009-2940
    Schlagwort(e): Dinuclear rhodium and iridium complexes ; Bis(cyclopentadienyl)methane dianion as bridging ligand ; Substitution and bridge-splitting reactions ; Rhodium complexes ; Iridium complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bis(cyclopentadienyl)methane-Bridged Dinuclear Complexes, IV[1].  -  Synthesis, Structure, and Reactivity of Dinuclear Rhodium and Iridium Complexes in the Oxidation State +I and +III with the Bis(cyclopentadienyl)methane Dianion as Bridging LigandThe rhodium compounds [CH2(C5H4)2][Rh(L)(C2H4)]2 (2, 4) were prepared from [RhCl(L)(C2H4)]2 (1, 3) and CH2(C5H4)2Li2 in 92 and 73% yield, respectively. The reaction of 4 with Cl2, Br2, and I2 led to the almost quantitative formation of the dihalogeno derivatives [CH2(C5H4)2][RhX2(PiPr3)]2 (6-8), which on treatment with excess NaBH4 and methanol gave the dihydride [CH2(C5H4)2][RhH2(PiPr3)]2 (10). From [RhCl(C8H14)2]2 (12), PiPr3, and CH2(C5H5)2 the chloro(hydrido)rhodium complex [CH2(C5H4)2][RhH(Cl)(PiPr3)]2 (13) was obtained. Protonation of 10 with CF3CO2H in the presence of NH4PF6 gave the PF6 salt of the hydrido-bridged cation {[CH2(C5H4)2]-[RhH(PiPr3)]2(μ-H)}+ (14) of which the crystal structure was determined. In solution, fluxional behavior of the cation was observed. The dimethyl compound [CH2(C5H4)2][Rh(CH3)2-(PiPr3)]2 (17), prepared from 6, 7, or 8 and LiCH3 or CH3MgI in 80% yield, reacted with CF3CO2H at  -  78° C to give the tri-fluoroacetato derivative 18; this on treatment with P(OMe)3 and dmpe formed the dicationic complexes 19 and 20, respectively. The dinuclear iridium compounds [CH2(C5H4)2]-[Ir(olefin)2]2 (26, 27) and [CH2(C5H4)2][Ir(C8H12)]2 (28) were prepared from [IrCl(L)2]2 (23-25) and CH2(C5H4)2Li2 and used for the synthesis of {[CH2(C5H4)2][IrX2]2}n (29, 30). Compounds 29 and 30 served as starting materials for the preparation of the dinuclear derivatives [CH2(C5H4)2][IrX2(L)]2 (31-34) and {[CH2(C5H4)2][IrBr2]2(μ-dipy)} (35) and finally also for the dihydrido complex [CH2(C5H4)2][IrH2(PiPr3)]2 (36).
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  • 67
    Publikationsdatum: 2024-02-07
    Beschreibung: In recent decades, the increase in terrestrial inputs to freshwater and coastal ecosystems, especially occurring at northern latitudes, has led to a process of water color darkening known as “brownification.” To assess how brownification affects plankton community composition and functioning in northern coastal areas, an in situ mesocosm experiment using a highly colored humic substance to simulate a brownification event was performed in a North Atlantic bay (Hopavågen, Norway) in August 2019. Manual sampling for analyses of nutrient concentrations, phytoplankton pigments and zooplankton abundances was combined with high-frequency (every 15 min) monitoring of key environmental variables to investigate the response of the plankton community in terms of oxygen metabolism and community composition. In response to brownification, the oxygen gross primary production (GPP) and community respiration (R) slowed down significantly, by almost one-third. However, GPP and R both decreased to the same extent; thus, the oxygen metabolic balance was not affected. Moreover, the chlorophyll-a concentration significantly decreased under brownification, by 9% on average, and the chemotaxonomic pigment composition of the phytoplankton changed, indicating their acclimation to the reduced light availability. In addition, brownification seemed to favor appendicularians, the dominant mesozooplankton group in the mesocosms, which potentially contributed to lowering the phytoplankton biomass. In conclusion, the results of this in situ mesocosm experiment suggest that brownification could induce significant changes in phytoplankton and zooplankton community composition and significantly alter the overall oxygen metabolism of plankton communities in a northern Atlantic bay.
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  • 68
    Publikationsdatum: 2023-06-29
    Materialart: Report , NonPeerReviewed
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  • 69
    Publikationsdatum: 2024-02-07
    Beschreibung: In this study, we investigate the maximum physical and biogeochemical potential of macroalgae open-ocean mariculture and sinking (MOS) as an ocean-based carbon dioxide removal (CDR) method. Embedding a macroalgae model into an Earth system model, we simulate macroalgae mariculture in the open-ocean surface layer followed by fast sinking of the carbon-rich macroalgal biomass to the deep seafloor (depth〉3000 m), which assumes no remineralization of the harvested biomass during the quick sinking. We also test the combination of MOS with artificial upwelling (AU), which fertilizes the macroalgae by pumping nutrient-rich deeper water to the surface. The simulations are done under RCP 4.5, a moderate-emissions pathway. When deployed globally between years 2020 and 2100, the carbon captured and exported by MOS is 270 PgC, which is further boosted by AU of 447 PgC. Because of feedbacks in the Earth system, the oceanic carbon inventory only increases by 171.8 PgC (283.9 PgC with AU) in the idealized simulations. More than half of this carbon remains in the ocean after cessation at year 2100 until year 3000. The major side effect of MOS on pelagic ecosystems is the reduction of phytoplankton net primary production (PNPP) due to the competition for nutrients with macroalgae and due to canopy shading. MOS shrinks the mid-layer oxygen-minimum zones (OMZs) by reducing the organic matter export to, and remineralization in, subsurface and intermediate waters, while it creates new OMZs on the seafloor by oxygen consumption from remineralization of sunken biomass. MOS also impacts the global carbon cycle by reducing the atmospheric and terrestrial carbon reservoirs when enhancing the ocean carbon reservoir. MOS also enriches dissolved inorganic carbon in the deep ocean. Effects are mostly reversible after cessation of MOS, though recovery is not complete by year 3000. In a sensitivity experiment without remineralization of sunken MOS biomass, the whole of the MOS-captured carbon is permanently stored in the ocean, but the lack of remineralized nutrients causes a long-term nutrient decline in the surface layers and thus reduces PNPP. Our results suggest that MOS has, theoretically, considerable CDR potential as an ocean-based CDR method. However, our simulations also suggest that such large-scale deployment of MOS would have substantial side effects on marine ecosystems and biogeochemistry, up to a reorganization of food webs over large parts of the ocean.
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  • 70
    Publikationsdatum: 2023-02-08
    Beschreibung: Oceanic transient tracers have been concerned for more than four decades due to their ability in visualizing and quantifying ocean ventilation and understanding the effects of changing climate. They trace pathways climate anomalies follow as they enter and move through the ocean and provide us with valuable time information. When such time information is interpreted depending on input function (time changing concentrations), they are chronological transient tracers, such as dichlorodifluoromethane (CFC-12) and sulfur hexafluoride (SF6). During the past ~15 years, the non-monotonous change of atmospheric history of CFC-12 limited its ability as an oceanic transient tracer for recently ventilated water masses, but it still works for deep waters. Therefore, we took the Mediterranean Sea as an example and investigated the recent changes in deep ventilation based on long-term observations of CFC-12 and SF6 in the first manuscript. Since a combination of multiple transient tracers can better interpret ocean ventilation, we looked for and evaluated potential novel transient tracers: hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) in the second and third manuscripts. The specific findings are described below. In the first study, highly variable deep ventilation in the Mediterranean Sea in time and space are reported based on a combination of observations of traditional chronological transient tracers, hydrographic properties and apparent oxygen utilization from 13 cruises conducted during 1987-2018. Spatially, both the Eastern and Western Mediterranean Deep Water (EMDW and WMDW) show a general west-to-east gradient of increasing salinity and potential temperature but decreasing oxygen and transient tracer concentrations. Temporally, stagnant and weak ventilation is found in most areas of the EMDW during the last decade in spite of prevailing ventilation in the Adriatic Deep Water between 2011 and 2016, which could be a result of the weakened Adriatic source intensity. In the Western Mediterranean Sea, enhanced ventilation after the Western Mediterranean Transition (WMT) event is observed, and slightly weakened ventilation after 2016 could be a combined influence from the Eastern (for the weakened Adriatic source intensity) and the Western (for the weakened influence from the WMT event) Mediterranean Sea. In the second and third studies, we explored and evaluated potential novel chronological transient tracers: chlorodifluoromethane (HCFC-22), 1,1-dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b), 1,1,1,2-tetrafluoroethane (HFC-134a), pentafluoroethane (HFC-125), fluoroform (HFC-23), carbon tetrafluoride (PFC-14, CF4) and hexafluoroethane (PFC-116) from four aspects: input function (including atmospheric history and historical surface saturation), seawater solubility, feasibility of measurement and stability in seawater. By comprehensive analysis and evaluation, the most promising oceanic transient tracers are HCFC-142b and HCFC-141b currently since they fulfil essential requirements by virtue of well-documented atmospheric history, established seawater solubility, feasible measurements and inertness in seawater. However, they will likely only work for the next few years/decades considering the restrictions on their production and consumption imposed by the Montreal Protocol and their (future) decreasing atmospheric mole fractions. The compounds that have the greatest potential as oceanic transient tracers in the future are PFC-14 and PFC-116 because of their high stability in seawater, the long and well-document atmospheric concentration histories and well-constructed seawater solubility functions. The challenge is how to measure them accurately due to their low solubility. For HFC-134a, we are not able to fully evaluate its potential as a tracer due to the inconclusive results, especially on its solubility and stability in seawater, but also with regard to potential analytical challenges. HFC-125, HFC-23, and HCFC-22 can no longer be considered because there are alternative tracers with similar input functions that are better suited as oceanic transient tracers. In total, this work helps us understand ocean ventilation in the Mediterranean Sea in the past ~30 years (with an emphasis on the recent changes) from the perspective of the traditional chronological transient tracers, as well as explored and evaluated the potential novel chronological transient tracers in the ocean. The outcome sets the base for further investigation of these alternative tracers in order to better interpreting ventilation in the global ocean and understanding the effects of climate change.
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  • 71
    ISSN: 0009-2940
    Schlagwort(e): Metal dithiolenes ; Dipyridinioethylene dihalides ; Charge-Transfer complexes ; Electrical conductivity ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Charge-Transfer Complexes of Metal Dithiolenes, XIII[1]. - cis-trans-Photoisomerisable Viologens as Redoxactive Acceptors  -  Synthesis and Electrical ConductivityIon Pair Charge-Transfer (IPCT) complexes of the type [A2+[ML2]2-} (1a-f to 4a-f) are synthesized from dianionic metal dithiolenes [M = Ni, Zn, L = cis-1,2-dicyano-1,2-ethene-dithiolate (mnt2-), 2-thioxo-1,3-dithiol-4,5-dithiolate (dmit2-)] and dicationic viologens [A2+ = 4,4′-(1,2-ethenediyl)bis(1-alkylpyridinium)]. The acceptors can exist as cis/trans isomers and may have coordinating properties in the case of 1-cyanoalkyl groups. The IPCT bands are in the range of 500 to 1200 nm and their energy follows the Hush-Marcus relation. For the nickel complexes the reorganization energy amounts to 73, for the zinc compounds to 115 kJ/mol. As shown by X-ray analysis of {A2+[Ni(mnt)2]2-} (2d), A2+ = trans-4,4′-(1,2-ethenediyl)-bis[1-(3-cyanopropyl)pyridinium], the structure consists of stacks of alternating donors and acceptors with a typical plane-to-plane distance of 350 pm. There is no interaction between the cyano group of the acceptor and the nickel atom of the donor. The electrical conductivities of the nickel compounds are in the range of 5 · 10-6 to 3 · 10-11 Ω-1 cm-1, and the corresponding activation energies vary from 0.24 to 0.61 eV. For the dmit complexes these values agree well with the free activation enthalpy of the electron transfer reaction A2+ + [ML2]2- → A+ + [ML2]- calculated from the Hush-Marcus model. This suggests that charge carrier generation occurs by electron transfer. When a trans acceptor is replaced by its cis isomer in [A2+[NiL2]2-}, conductivity changes from 5 · 10-7 to 5 · 10-6 Ω-1 cm-1 and the activation energy from 0.43 to 0.24 eV, when L - dmit2- but stays at about 1 · 10-8 Ω-1 cm-1 for L = mnt2-.
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  • 72
    Publikationsdatum: 2024-02-09
    Beschreibung: The understanding of coupled thermo-hydromechanical behaviour of fault zones or in naturally fractured reservoirs is essential both for fundamental and applied sciences and in particular for the safety assessment of radioactive waste disposal facilities. The overall objective of the CHENILLE project is to better understand the physical processes resulting from thermal and hydraulic loading in a small fault zone in a highly consolidated shale formation. Consequently, a thermally controlled in-situ fluid injection experiment is intended to be performed on a strikeslip fault zone outcropping at the Tournemire/France Underground Research Laboratory (URL). A heating system has been installed around the injection area to enable a precise and controlled incremental increase of the thermal load. Different monitoring systems are designed to measure the seismic and aseismic deformation induced either by thermal and/or by hydraulic loading. The seismic monitoring system is composed of Acoustic Emission (AE) and broadband seismic sensors enabling monitoring of seismic fracturing processes down to sub-decimetre scale as well as slow deformation processes. Furthermore, we are about to install an injection chamber allowing to perform a controlled gaz injection test. The injection borehole will also be partly equipped with fiber optics in order to measure temperature in a distributed manner in the borehole. Time-lapse active seismic surveys are scheduled for before and after the experiment to image the structural network but also to detect the appearance of new structures triggered from the hydro-thermal pressurization of the fault as well as eventual changes in the velocity field.
    Sprache: Englisch
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  • 73
    Publikationsdatum: 2024-02-07
    Beschreibung: The tunicate Ciona intestinalis is one of the most notorious invasive ascidian species. In Prince Edward Island (PEI, Canada), C. intestinalis causes heavy fouling on farmed mussels leading to significant economic losses. Except for general beneficial eco-physiological characteristics of invasive ascidians, reasons underlying C. intestinalis’ invasiveness remain obscure. This study aimed to shed light on two additional factors potentially promoting its invasion success, i.e., bioactive secondary metabolites and associated microbiota, which reportedly contribute to the invasiveness of other marine species. Therefore, microbiomes and metabolomes of invasive (PEI) and native (Helgoland and Kiel, Germany) C. intestinalis populations were comparatively studied, a novelty in invasive ascidian research. Apart from being problematic invasive species, ascidians and their associated microbiota are a rich source for bioactive marine natural products (MNPs) relevant for human health. However, the biodiscovery potential of C. intestinalis-associated microorganisms remains largely unknown. Accordingly, this doctoral research project targeted to explore bioactivities and the chemical repertoire of culturable bacteria and fungi associated with C. intestinalis. Amplicon sequencing-based bacterial community analysis of gut, tunic, and seawater (control) samples revealed species-specificity and a diverse microbiota (39 phyla). The UPLC-MS/MS-based untargeted metabolomics approach revealed a diverse chemical inventory dominated by alkaloids and lipids. In addition to core bacteria and metabolites present in all samples, also tissue- and location-specific bacteria and metabolites were observed. Notably, highest microbial and chemical diversity were detected in the invasive C. intestinalis population (PEI). In combination, these results suggest a high adaptive capacity of C. intestinalis. In addition, several detected bacteria and secondary metabolites reportedly have antimicrobial, antifouling, and other relevant bioactivities, potentially promoting its overall health, fitness, and competitiveness. In conjunction with microbiome data, this first global metabolome study on C. intestinalis indicated microbial associates and chemical weapons as additional relevant factors promoting its invasion success. Therefore, this work contributes important basic knowledge for future projects scrutinizing the invasiveness of C. intestinalis. To investigate the potential of microorganisms associated with C. intestinalis in marine biodiscovery, isolates were obtained from tunics (T) and guts (G) due to their pivotal functions for the ascidian’s defense against, e.g., pathogens, and their reportedly different bacterial communities. In total, 89 (T) and 61 (G) bacteria as well as 22 (T) and 40 (G) fungi were isolated and identified from Helgoland and Kiel specimens. Many extracts showed antibacterial (T: 42%, G: 64%), antifungal (T: 10%, G: 11%), and/or anticancer (T: 6%, G: 22%) activities. A 2-step selection procedure considering bioactivity and metabolite profiles was applied to prioritize the most promising MNPs producers. This led to the selection of seven tunic- and nine gut-derived microbial extracts affiliated to the fungal group of ascomycetes (69%) and the bacterial taxa Actinobacteria (25%) and Bacillus sp. (6%). Through an UPLC-MS/MS-based dereplication workflow including molecular networking, in-silico approaches and manual database comparison, 170 compounds belonging to 〉40 different chemical families were putatively annotated, displaying a vast chemical diversity. Although this represents a significant increase in annotation rates compared to previous studies, still many compounds even from well-studied organisms (e.g., Penicillium and Streptomyces spp.) remained unknown. In summary, this study demonstrated a huge pharmaceutical potential of the culturable microbiota associated with C. intestinalis, including discovery of various putatively novel compounds. Application of novel selection and integrated dereplication procedures proved successful for strain prioritization and compound annotation. Furthermore, this strategy highlighted particularly fungi as so far uncharted and exceptionally promising resource for putatively novel anticancer and antimicrobial lead compounds of high interest.
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  • 74
    Publikationsdatum: 2023-07-07
    Beschreibung: Innerhalb des Projekts "Digitalisierung gestalten - Transformation zur Nachhaltigkeit ermöglichen" werden die besonderen Transformationspotenziale der Digitalisierung herausgearbeitet und für Deutschland am Beispiel der ausgewählten Handlungsfelder Mobilität, Circular Economy sowie Landwirtschaft und Ernährung diskutiert. Dieser Bericht adressiert das Handlungsfeld einer klimaschonenden und ressourceneffizienten Kreislaufwirtschaft, die Circular Economy. Bisher wird Kreislaufwirtschaft dabei vor allem mit Fokus auf Recycling und Wiederverwertung von Materialien diskutiert. Das greift jedoch zu kurz - es muss um die Skalierung von neuen, ressourcenschonenden Geschäftsmodellen und der umfassenden Transformation von Wertschöpfungsketten und Industriestrukturen gehen. Die Analyse zeigt: richtig eingesetzt ist Digitalisierung unverzichtbar für diesen Wandel. Der vorliegende Bericht möchte Anstöße für diesen Weg liefern und neue Impulse für eine klima- und ressourcenschonende Industrietransformation in Deutschland setzen. Der Bericht verarbeitet dabei Ergebnisse eines interdisziplinären Workshops zum Thema "Die digital-ökologische Industrietransformation gestalten - Geschäftsmodelle und politische Rahmenbedingungen für Klima- und Ressourcenschutz" mit Expertinnen und Experten aus Forschung, Zivilgesellschaft, Behörden und Privatunternehmen.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Deutsch
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  • 75
    Publikationsdatum: 2023-02-08
    Beschreibung: Eutrophication is a serious threat to aquatic ecosystems globally with pronounced negative effects in the Baltic and other semi-enclosed estuaries and regional seas, where algal growth associated with excess nutrients causes widespread oxygen free “dead zones” and other threats to sustainability. Decades of policy initiatives to reduce external (land-based and atmospheric) nutrient loads have so far failed to control Baltic Sea eutrophication, which is compounded by significant internal release of legacy phosphorus (P) and biological nitrogen (N) fixation. Farming and harvesting of the native mussel species (Mytilus edulis/trossulus) is a promising internal measure for eutrophication control in the brackish Baltic Sea. Mussels from the more saline outer Baltic had higher N and P content than those from either the inner or central Baltic. Despite their relatively low nutrient content, harvesting farmed mussels from the central Baltic can be a cost-effective complement to land-based measures needed to reach eutrophication status targets and is an important contributor to circularity. Cost effectiveness of nutrient removal is more dependent on farm type than mussel nutrient content, suggesting the need for additional development of farm technology. Furthermore, current regulations are not sufficiently conducive to implementation of internal measures, and may constitute a bottleneck for reaching eutrophication status targets in the Baltic Sea and elsewhere.
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  • 76
    Publikationsdatum: 2023-10-11
    Beschreibung: Most large scale studies assessing climate change impacts on crops are performed with simulations of single crops and with annual reinitialization of the initial soil conditions. This is in contrast to the reality that crops are grown in rotations, often with sizable proportion of the preceding crop residue to be left in the fields and varying soil initial conditions from year to year. In this study, the sensitivity of climate change impacts on crop yield and soil organic carbon to assumptions about annual model reinitialization, specification of crop rotations and the amount of residue retained in fields was assessed for seven main crops across Europe. Simulations were conducted for a scenario period 2040-2065 relative to a baseline from 1980-2005 using the SIMPLACE1modelling framework. Results indicated across Europe positive climate change impacts on yield for C3 crops and negative impacts for maize. The consideration of simulating rotations did not have a benefit on yield variability but on relative yield change in response to climate change which slightly increased for C3 crops and decreased for C4 crops when rotation was considered. Soil organic carbon decreased under climate change in both simulations assuming a continuous monocrop and plausible rotations by between 3% and 10% depending on the residue management strategy.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/article
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  • 77
    Publikationsdatum: 2024-02-07
    Beschreibung: Based on the Baltic Earth Assessment Reports of this thematic issue in Earth System Dynamics and recent peer-reviewed literature, current knowledge of the effects of global warming on past and future changes in climate of the Baltic Sea region is summarised and assessed. The study is an update of the Second Assessment of Climate Change (BACC II) published in 2015 and focuses on the atmosphere, land, cryosphere, ocean, sediments, and the terrestrial and marine biosphere. Based on the summaries of the recent knowledge gained in palaeo-, historical, and future regional climate research, we find that the main conclusions from earlier assessments still remain valid. However, new long-term, homogenous observational records, for example, for Scandinavian glacier inventories, sea-level-driven saltwater inflows, so-called Major Baltic Inflows, and phytoplankton species distribution, and new scenario simulations with improved models, for example, for glaciers, lake ice, and marine food web, have become available. In many cases, uncertainties can now be better estimated than before because more models were included in the ensembles, especially for the Baltic Sea. With the help of coupled models, feedbacks between several components of the Earth system have been studied, and multiple driver studies were performed, e.g. projections of the food web that include fisheries, eutrophication, and climate change. New datasets and projections have led to a revised understanding of changes in some variables such as salinity. Furthermore, it has become evident that natural variability, in particular for the ocean on multidecadal timescales, is greater than previously estimated, challenging our ability to detect observed and projected changes in climate. In this context, the first palaeoclimate simulations regionalised for the Baltic Sea region are instructive. Hence, estimated uncertainties for the projections of many variables increased. In addition to the well-known influence of the North Atlantic Oscillation, it was found that also other low-frequency modes of internal variability, such as the Atlantic Multidecadal Variability, have profound effects on the climate of the Baltic Sea region. Challenges were also identified, such as the systematic discrepancy between future cloudiness trends in global and regional models and the difficulty of confidently attributing large observed changes in marine ecosystems to climate change. Finally, we compare our results with other coastal sea assessments, such as the North Sea Region Climate Change Assessment (NOSCCA), and find that the effects of climate change on the Baltic Sea differ from those on the North Sea, since Baltic Sea oceanography and ecosystems are very different from other coastal seas such as the North Sea. While the North Sea dynamics are dominated by tides, the Baltic Sea is characterised by brackish water, a perennial vertical stratification in the southern subbasins, and a seasonal sea ice cover in the northern subbasins.
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  • 78
    Publikationsdatum: 2024-02-08
    Beschreibung: Climate tipping elements are large-scale subsystems of the Earth that may transgress critical thresholds (tipping points) under ongoing global warming, with substantial impacts on biosphere and human societies. Frequently studied examples of such tipping elements include the Greenland Ice Sheet, the Atlantic Meridional Overturning Circulation (AMOC), permafrost, monsoon systems, and the Amazon rainforest. While recent scientific efforts have improved our knowledge about individual tipping elements, the interactions between them are less well understood. Also, the potential of individual tipping events to induce additional tipping elsewhere, or stabilize other tipping elements is largely unknown. Here, we map out the current state of the literature on the interactions between climate tipping elements and review the influences between them. To do so, we gathered evidence from model simulations, observations and conceptual understanding, as well as examples of paleoclimate reconstructions where multi-component or spatially propagating transitions were potentially at play. While un- certainties are large, we find indications that many of the interactions between tipping elements are destabilizing. Therefore, we conclude that tipping elements should not only be studied in isolation, but more emphasis has to be put on potential interactions. This means that tipping cascades can neither be ruled out on centennial to millennial timescales at global warming levels between 1.5–2.0◦C, nor on shorter timescales if global warming would surpass 2.0◦C. At these higher levels of global warming, tipping cascades may then include fast tipping elements such as the AMOC or the Amazon rainforest. To address crucial knowledge gaps in tipping element interactions, we propose four strategies forward combining observation-based approaches, Earth system modeling expertise, computational advances, and expert knowledge.
    Sprache: Englisch
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  • 79
    Publikationsdatum: 2024-02-07
    Beschreibung: This paper presents a modelling study on the fate of CHBr3 and its product gases in the troposphere within the context of tropical deep convection. A cloud-scale case study was conducted along the west coast of Borneo, where several deep convective systems were triggered on the afternoon and early evening of 19 November 2011. These systems were sampled by the Falcon aircraft during the field campaign of the SHIVA project and analysed using a simulation with the cloud-resolving meteorological model C-CATT-BRAMS at 2x2 km resolution that represents the emissions, transport by large-scale flow, convection, photochemistry, and washout of CHBr3 and its product gases (PGs). We find that simulated CHBr3 mixing ratios and the observed values in the boundary layer and the outflow of the convective systems agree. However, the model underestimates the background CHBr3 mixing ratios in the upper troposphere, which suggests a missing source at the regional scale. An analysis of the simulated chemical speciation of bromine within and around each simulated convective system during the mature convective stage reveals that 〉 85% of the bromine derived from CHBr3 and its PGs is transported vertically to the point of convective detrainment in the form of CHBr3 and that the remaining small fraction is in the form of organic PGs, principally insoluble brominated carbonyls produced from the photo-oxidation of CHBr3. The model simulates that within the boundary layer and free troposphere, the inorganic PGs are only present in soluble forms, i.e. HBr, HOBr, and BrONO2, and, consequently, within the convective clouds, the inorganic PGs are almost entirely removed by wet scavenging. We find that HBr is the most abundant PG in background lower-tropospheric air and that this prevalence of HBr is a result of the relatively low background tropospheric ozone levels at the regional scale. Contrary to a previous study in a different environment, for the conditions in the simulation, the insoluble Br-2 species is hardly formed within the convective systems and therefore plays no significant role in the vertical transport of bromine. This likely results from the relatively small quantities of simulated inorganic bromine involved, the presence of HBr in large excess compared to HOBr and BrO, and the relatively efficient removal of soluble compounds within the convective column.
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  • 80
    Publikationsdatum: 2024-01-30
    Beschreibung: Coastal upwelling areas are extraordinarily productive environments where prokaryotic communities, the principal remineralizers of dissolved organic matter (DOM), rapidly respond to phytoplankton bloom and decay dynamics. Nevertheless, the extent of variability of key microbial functions in such dynamic waters remains largely unconstrained. Our metatranscriptomics analyses of 162 marker genes encoding ecologically relevant prokaryotic functions showed distinct spatial-temporal patterns in the NW Iberian Peninsula upwelling area. Short-term (daily) changes in specific bacterial functions associated with changes in biotic and abiotic factors were superimposed on seasonal variability. Taxonomic and functional specialization of prokaryotic communities, based mostly on different resource acquisition strategies, was observed. Our results uncovered the potential influence of prokaryotic functioning on phytoplankton bloom composition and development (e.g., Cellvibrionales and Flavobacteriales increased relative gene expression related to vitamin B12 and siderophore metabolisms during Chaetoceros and Dinophyceae summer blooms). Notably, bacterial adjustments to C- or N-limitation and DMSP availability during summer phytoplankton blooms and different spatial-temporal patterns of variability in the expression of genes with different phosphate affinity indicated a complex role of resource availability in structuring bacterial communities in this upwelling system. Also, a crucial role of Cellvibrionales in the degradation of DOM (carbohydrate metabolism, TCA cycle, proteorhodopsin, ammonium, and phosphate uptake genes) during the summer phytoplankton bloom was found. Overall, this dataset revealed an intertwined mosaic of microbial interactions and nutrient utilization patterns along a spatial-temporal gradient that needs to be considered if we aim to understand the biogeochemical processes in some of the most productive ecosystems in the world´s oceans.
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  • 81
    facet.materialart.
    Unbekannt
    Copernicus Publications
    In:  EPIC3The Cryosphere, Copernicus Publications, 17(11), pp. 4903-4916, ISSN: 1994-0416
    Publikationsdatum: 2024-05-21
    Beschreibung: Reliable in situ surface mass balance (SMB) estimates in polar regions are scarce due to limited spatial and temporal data availability. This study aims at deriving automated and continuous specific SMB time series for fast-moving parts of ice sheets and shelves (flow velocityg10a-1) by developing a combined global navigation satellite system (GNSS) reflectometry and refractometry (GNSS-RR) method. In situ snow density, snow water equivalent (SWE), and snow deposition or erosion are estimated simultaneously as an average over an area of several square meters and independently on weather conditions. The combined GNSS-RR method is validated and investigated regarding its applicability to a moving, high-latitude ice shelf. A combined GNSS-RR system was therefore installed in November 2021 on the Ekström ice shelf (flow velocityĝ€¯≈ĝ€¯150a-1) in Dronning Maud Land, Antarctica. The reflected and refracted GNSS observations from the site are post-processed to obtain snow accumulation (deposition and erosion), SWE, and snow density estimates with a 15ĝ€¯min temporal resolution. The results of the first 16 months of data show a high level of agreement with manual and automated reference observations from the same site. Snow accumulation, SWE, and density are derived with uncertainties of around 9ĝ€¯cm, 40m-2ĝ€¯a-1, and 72m-3, respectively. This pilot study forms the basis for extending observational networks with GNSS-RR capabilities, particularly in polar regions. Regional climate models, local snow modeling, and extensive remote sensing data products will profit from calibration and validation based on such in situ time series, especially if many such sensors will be deployed over larger regional scales.
    Repository-Name: EPIC Alfred Wegener Institut
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  • 82
    Publikationsdatum: 2024-01-29
    Beschreibung: Reliable in situ surface mass balance (SMB) estimates in polar regions are scarce due to limited spatial and temporal data availability. This study aims at deriving automated and continuous specific SMB time series for fast-moving parts of ice sheets and shelves (flow velocity 〉 10 m a−1) by developing a combined global navigation satellite system (GNSS) reflectometry and refractometry (GNSS-RR) method. In situ snow density, snow water equivalent (SWE), and snow deposition or erosion are estimated simultaneously as an average over an area of several square meters and independently on weather conditions. The combined GNSS-RR method is validated and investigated regarding its applicability to a moving, high-latitude ice shelf. A combined GNSS-RR system was therefore installed in November 2021 on the Ekström ice shelf (flow velocity ≈ 150 m a−1) in Dronning Maud Land, Antarctica. The reflected and refracted GNSS observations from the site are post-processed to obtain snow accumulation (deposition and erosion), SWE, and snow density estimates with a 15 min temporal resolution. The results of the first 16 months of data show a high level of agreement with manual and automated reference observations from the same site. Snow accumulation, SWE, and density are derived with uncertainties of around 9 cm, 40 kg m−2 a−1, and 72 kg m−3, respectively. This pilot study forms the basis for extending observational networks with GNSS-RR capabilities, particularly in polar regions. Regional climate models, local snow modeling, and extensive remote sensing data products will profit from calibration and validation based on such in situ time series, especially if many such sensors will be deployed over larger regional scales.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/article
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  • 83
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 81-83 (Jan. 1993), p. 619-624 
    ISSN: 1013-9826
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Materialart: Digitale Medien
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  • 84
    Publikationsdatum: 2023-01-13
    Beschreibung: Imaging the critical zone at depth, where intact bedrock transforms into regolith, is critical in understanding the interaction between geological and biological processes. We acquired a 500 m long near-surface seismic to investigate the weathering structure in the Santa Gracia National Reserve, Chile which is located in a granitic environment in an arid climate. Data processing comprised the combination of two seismic approaches: 1) body wave tomography, and 2) Multichannel Analysis of Surface Wave (MASW) with Bayesian inversion. This allowed us to derive P-wave and S-wave velocity models down to 90 and 70 m depth, respectively. By callibrating of the seismic results with those from an 87-m deep borehole that is crossed by the profile. We identified the boundaries of saprolite, weathered bedrock, bedrock. These divisions are indicated in the seismic velocity variations and refer to weathering effects at depth. The thereby determined weathering front in borehole location can be traced down to 30 m depth. The modelled lateral extent of the weathering front, however, cannot be described by established weathering front model. The discrepancies suggest more a more complex interaction between different aspects such as precipitation and topography in controlling the weathering front depth.
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  • 85
    Publikationsdatum: 2024-02-19
    Beschreibung: Microbes are the fundamental drivers of Earth’s biogeochemical cycles. Their enormous taxonomic, functional and metabolic diversity are of essential importance for ecosystem functioning − from cellular to community scales, over time and space. Among the multitude of microbial metabolisms in the oceans, polysaccharide degradation is one key process, featuring distinct substrate niches and bacteria-algae interactions. Nonetheless, many aspects regarding the distribution of polysaccharide-degrading taxa and their genetic regulation remain open. One central question is how hydrolytic abilities, and the diversity of metabolic functions in general, affect microbiome assembly over time. Studying temporal variability is especially important in vulnerable and changing systems such as the polar oceans, where the climate crisis exerts substantial pressure on biological communities. This Habilitation summarizes my research on bacterial polysaccharide degradation, intraspecific diversity, and microbiome seasonality in the Arctic Ocean. The enclosed studies present interdisciplinary insights into the biogeography, identity, genetic repertoire, and regulatory dynamics of polysaccharide degraders on cellular, microhabitat and ocean-wide scales. Experimental incubations revealed distinct “hydrolytic community fingerprints” in the Atlantic, Pacific, and Southern Oceans. Furthermore, studying the genetic machinery and cellular regulation under both simple and complex substrate conditions, including dissolved and particulate polysaccharides, illuminated the microscale underpinnings of larger community dynamics. This integrated molecular and culture-based evidence contributes to a conceptual perspective on polysaccharide utilization in contrasting marine systems. The establishment of model organisms was essential for studying genetic regulation and intraspecific diversity; addressing hydrolytic capacities and other traits including siderophore production, aromatics degradation, and metabolite secretion – mediators of central element cycles and chemical ecology. Connecting genotypes to niches furthermore contributed to broader eco-evolutionary concepts on species delineation and population assembly. Finally, my research characterized microbial communities over seasonal and environmental gradients in the Arctic Ocean. Time-series observations via autonomous devices revealed community dynamics over polar day and night, and across different sea-ice and polar water regimes. This microbial inventory in the environmental context establishes a baseline of Arctic microbial ecology, and allows benchmarking future ecosystem shifts. Overall, the presented research contributes important conclusions for the understanding of microbial diversity and biogeochemical functions in cellular, spatial and temporal dimensions, underlining the relevance of microbes for ecosystem functioning in the current and future ocean.
    Repository-Name: EPIC Alfred Wegener Institut
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  • 86
    Publikationsdatum: 2024-02-07
    Beschreibung: Highlights: • Allorecognition assessment of fish with (N. ophidion) and without (S. typhle) MHCII. • Using fin-transplantations of self and non-self tissue with transcriptomics. • Upregulated gene expression of cytotoxic T-cell/MHCI activity in S. typhle. • Indications of cytotoxic/MHCI gene upregulation in S. typhle allografts. • MHCI downregulation in N. ophidion autografts, suggests immunological tolerance. Abstract: Natural occurrences of immunodeficiency by definition should lead to compromised immune function. The major histocompatibility complexes (MHC) are key components of the vertebrate adaptive immune system, charged with mediating allorecognition and antigen presentation functions. To this end, the genomic loss of the MHC II pathway in Syngnathus pipefishes raises questions regarding their immunological vigilance and allorecognition capabilities. Utilising allograft and autograft fin-transplants, we compared the allorecognition immune responses of two pipefish species, with (Nerophis ophidion) and without (Syngnathus typhle) a functional MHC II. Transcriptome-wide assessments explored the immunological tolerance and potential compensatory measures occupying the role of the absent MHC II. Visual observations suggested a more acute rejection response in N. ophidion allografts compared with S. typhle allografts. Differentially expressed genes involved in innate immunity, angiogenesis and tissue recovery were identified among transplantees. The intriguing upregulation of the cytotoxic T-cell implicated gzma in S. typhle allografts, suggests a prominent MHC I related response, which may compensate for the MHC II and CD4 loss. MHC I related downregulation in N. ophidion autografts hints at an immunological tolerance related reaction. These findings may indicate alternative measures evolved to cope with the MHC II genomic loss enabling the maintenance of appropriate tolerance levels. This study provides intriguing insights into the immune and tissue recovery mechanisms associated with syngnathid transplantation, and can be a useful reference for future studies focusing on transplantation transcriptomics in non-model systems.
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  • 87
    Publikationsdatum: 2024-02-07
    Beschreibung: Biodegradable and compostable plastics are getting more attention as the environmental impacts of fossil-fuel-based plastics are revealed. Microbes can consume these plastics and biodegrade them within weeks to months under the proper conditions. The biobased polyhydroxyalkanoate (PHA) polymer family is an attractive alternative due to its physicochemical properties and biodegradability in soil, aquatic, and composting environments. Standard test methods are available for biodegradation that employ either natural inocula or defined communities, the latter being preferred for standardization and comparability. The original marine biodegradation standard test method ASTM D6691 employed such a defined consortium for testing PHA biodegradation. However, the taxonomic composition and metabolic potential of this consortium have never been confirmed using DNA sequencing technologies. To this end, we revived available members of this consortium and determined their phylogenetic placement, genomic sequence content, and metabolic potential. The revived members belonged to the Bacillaceae, Rhodobacteraceae, and Vibrionaceae families. Using a comparative genomics approach, we found all the necessary enzymes for both PHA production and utilization in most of the members. In a clearing-zone assay, three isolates also showed extracellular depolymerase activity. However, we did not find classical PHA depolymerases, but identified two potentially new extracellular depolymerases that resemble triacylglycerol lipases.
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  • 88
    Publikationsdatum: 2024-02-07
    Beschreibung: The main objective of the present study was to assess the effects of sulfur (S) nutrition on plant growth, overall quality, secondary metabolites, and antibacterial and radical scavenging activities of hydroponically grown lettuce cultivars. Three lettuce cultivars, namely, Pazmanea RZ (green butterhead, V1), Hawking RZ (green multi-leaf lettuce, V2), and Barlach RZ (red multi-leaf, V3) were subjected to two S-treatments in the form of magnesium sulfate (+S) or magnesium chloride (−S). Significant differences were observed under −S treatments, especially among V1 and V2 lettuce cultivars. These responses were reflected in the yield, levels of macro- and micro-nutrients, water-soluble sugars, and free inorganic anions. In comparison with the green cultivars (V1 and V2), the red-V3 cultivar revealed a greater acclimation to S starvation, as evidenced by relative higher plant growth. In contrast, the green cultivars showed higher capabilities in production and superior quality attributes under +S condition. As for secondary metabolites, sixteen compounds (e.g., sesquiterpene lactones, caffeoyl derivatives, caffeic acid hexose, 5-caffeoylquinic acid (5-OCQA), quercetin and luteolin glucoside derivatives) were annotated in all three cultivars with the aid of HPLC-DAD-MS-based untargeted metabolomics. Sesquiterpene lactone lactucin and anthocyanin cyanidin 3-O-galactoside were only detected in V1 and V3 cultivars, respectively. Based on the analyses, the V3 cultivar was the most potent radical scavenger, while V1 and V2 cultivars exhibited antibacterial activity against Staphylococcus aureus in response to S provision. Our study emphasizes the critical role of S nutrition in plant growth, acclimation, and nutritional quality. The judicious-S application can be adopted as a promising antimicrobial prototype for medical applications.
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  • 89
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 81-83 (Jan. 1993), p. 555-560 
    ISSN: 1013-9826
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    Publikationsdatum: 2023-02-08
    Beschreibung: Submarine groundwater discharge (SGD) into coastal areas is a common global phenomenon and is rapidly gaining scientific interest due to its influence on marine ecology, the coastal sedimentary environment and its potential as a future freshwater resource. We conducted an integrated study of hydroacoustic surveys combined with geochemical porewater and water column investigations at a well‐known groundwater seep site in Eckernförde Bay (Germany). We aim to better constrain the effects of shallow gas and SGD on high frequency multibeam backscatter data and to present acoustic indications for submarine groundwater discharge. Our high‐quality hydroacoustic data reveal hitherto unknown internal structures within the pockmarks in Eckernförde Bay. Using precisely positioned sediment core samples, our hydroacoustic‐geochemical approach can differentiate intra‐pockmark regimes that were formerly assigned to pockmarks of a different nature. We demonstrate that high‐frequency multibeam data, in particular the backscatter signals, can be used to detect shallow free gas in areas of enhanced groundwater advection in muddy sediments. Intriguingly, our data reveal relatively small (typically 〈15 m across) pockmarks within the much larger, previously mapped, pockmarks. The small pockmarks, which we refer to as “intra‐pockmarks”, have formed due to the localized ascent of gas and groundwater; they manifest themselves as a new type of ‘eyed’ pockmarks, revealed by their acoustic backscatter pattern. Our data suggest that, in organic‐rich muddy sediments, morphological lows combined with a strong multibeam backscatter signal can be indicative of free shallow gas and subsequent advective groundwater flow.
    Materialart: Article , PeerReviewed
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  • 91
    Publikationsdatum: 2024-02-07
    Beschreibung: The occurrence of European heat events has increased during the last two decades. European heat events are responsible for social, economic and environmental damage and are projected to increase in magnitude, frequency and duration under global warming, strengthening the interest about the contribution of different mechanisms. Using the ERA5 reanalysis product, we go beyond case studies relating European heat events with cold North Atlantic sea surface temperatures (SSTs), and perform a systematic approach with a composite analysis to investigate the link between North Atlantic SSTs in a domain south of Greenland and the 2m air temperature (T2m) over central Europe. Composites of different North Atlantic SST states show that events with a negative tendency of North Atlantic SSTs are often followed by positive European T2m anomalies during summers when the North Atlantic SSTs are persistently low for several months. Enhanced lower–tropospheric baroclinicity in the North Atlantic is followed during these events by a slantwise ascent and an enhanced upper–tropospheric waveguide, promoting a downstream development of an European ridge. A combination of a wave number 3 pattern and regionally confined Rossby wave activity contribute to a trough–ridge pattern in the North Atlantic–European sector. A composite of European heat events further confirms the lagged statistical relationship between cold North Atlantic SSTs with a negative tendency and positive European T2m anomalies. A negative tendency of North Atlantic SSTs precedes 15 of 18 European heat events, and cold North Atlantic SST conditions are present during 14 of 18 European heat events.
    Materialart: Article , PeerReviewed
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    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Publikationsdatum: 2024-02-07
    Beschreibung: Males and females follow distinct life-history strategies that have co-evolved with several sex-specific traits. Higher investment into parental investment (PI) demands an increased lifespan. Thus, resource allocation toward an efficient immune system is mandatory. In contrast, resources allocated toward secondary sexual signals (ornamentation) may negatively correlate with investment into immunity and ultimately result in a shorter lifespan. Previous studies have addressed how resource allocation toward single sex-specific traits impacts lifetime reproductive success (LRS). However, the trade-offs between diverse sex-specific characteristics and their impact on LRS remain largely unassessed impeding our understanding of life-history evolution. We have designed a theoretical framework (informed by experimental data and evolutionary genetics) that explores the effects of multiple sex-specific traits and assessed how they influence LRS. From the individual sex-specific traits, we inferred the consequences at the population level by evaluating adult sex ratios (ASR). Our theory implies that sex-specific resource allocation toward the assessed traits resulted in a biased ASR. Our model focuses on the impact of PI, ornamentation, and immunity as causal to biased ASR. The framework developed herein can be employed to understand the combined impact of diverse sex-specific traits on the LRS and the eventual population dynamics of particular model systems.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 93
  • 94
    Publikationsdatum: 2024-01-18
    Beschreibung: Accurate age estimates are crucial for assessing the life-histories of fish and providing management advice, but validation studies are rare for many species. We corroborated age estimates with annual cycles of oxygen isotopes (δ18O) in otoliths of 86 northern pike (Esox lucius) from the southern Baltic Sea, compared results with visual age estimates from scales and otoliths, and assessed bias introduced by different age-estimation structures on von Bertalanffy growth models and age-structured population models. Age estimates from otoliths were accurate, while age estimates from scales significantly underestimated the age of pike older than 6 years compared to the corroborated reference age. Asymptotic length () was larger, and the growth coefficient was lower for scale ages than for corroborated age and otolith age estimates. Consequentially, scale-informed population models overestimated maximum sustainable yield (), biomass at (), relative frequency of trophy fish (), and optimal minimum length limit but underestimated fishing mortality at (). Using scale-based ages to inform management regulations for pike may therefore result in conservative management and lost yield. The overestimated asymptotic length may instill unrealistic expectations of trophy potential in recreational anglers targeting large pike, while the overestimation in MSY would cause unrealistic expectations of yield potential in commercial fishers.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/article
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Publikationsdatum: 2024-04-10
    Beschreibung: Phytoplankton play a central role in the planetary cycling of important elements and compounds. Understanding how phytoplankton are responding to climate change is consequently a major question in Earth Sciences. Monitoring phytoplankton is key to answering this question. Satellite remote sensing of ocean colour is our only means of monitoring phytoplankton in the entire surface ocean at high temporal and large spatial scales, and the continuous ocean-colour data record is now approaching a length suitable for addressing questions around climate change, at least in some regions. Yet, developing ocean-colour algorithms for climate change studies requires addressing issues of ambiguity in the ocean-colour signal. For example, for the same chlorophyll-a concentration (Chl-a) of phytoplankton, the colour of the ocean can be different depending on the type of phytoplankton present. One route to tackle the issue of ambiguity is by enriching the ocean-colour data with information on sea surface temperature (SST), a good proxy of changes in three phytoplankton size classes (PSCs) independent of changes in total Chl-a, a measure of phytoplankton biomass. Using a global surface insitu dataset of HPLC (high performance liquid chromatography) pigments, size-fractionated filtration data, and concurrent satellite SST spanning from 1991 to 2021, we re-tuned, validated and advanced an SST-dependent three-component model that quantifies the relationship between total Chl-a and Chl-a associated with the three PSCs (pico-, nano- and microplankton). Similar to previous studies, striking dependencies between model parameters and SST were captured, which were found to improve model performance significantly. These relationships were applied to 40 years of monthly composites of satellite SST, and significant trends in model parameters were observed globally, in response to climate warming. Changes in these parameters highlight issues in estimating long-term trends in phytoplankton biomass (Chl-a) from ocean colour using standard empirical algorithms, which implicitly assume a fixed relationship between total Chl-a and Chl-a of the three size classes. The proposed ecological model will be at the centre of a new ocean-colour modelling framework, designed for investigating the response of phytoplankton to climate change, described in subsequent parts of this series of papers.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Publikationsdatum: 2024-02-07
    Beschreibung: The past and future evolution of the Antarctic Ice Sheet is largely controlled by interactions between the ocean and floating ice shelves. To investigate these interactions, coupled ocean and ice sheet model configurations are required. Previous modelling studies have mostly relied on high-resolution configurations, limiting these studies to individual glaciers or regions over short timescales of decades to a few centuries. We present a framework to couple the dynamic ice sheet model PISM (Parallel Ice Sheet Model) with the global ocean general circulation model MOM5 (Modular Ocean Model) via the ice shelf cavity model PICO (Potsdam Ice-shelf Cavity mOdel). As ice shelf cavities are not resolved by MOM5 but are parameterized with the PICO box model, the framework allows the ice sheet and ocean components to be run at resolutions of 16 km and 3∘ respectively. This approach makes the coupled configuration a useful tool for the analysis of interactions between the Antarctic Ice Sheet and the global ocean over time spans of the order of centuries to millennia. In this study, we describe the technical implementation of this coupling framework: sub-shelf melting in the ice sheet component is calculated by PICO from modelled ocean temperatures and salinities at the depth of the continental shelf, and, vice versa, the resulting mass and energy fluxes from melting at the ice–ocean interface are transferred to the ocean component. Mass and energy fluxes are shown to be conserved to machine precision across the considered component domains. The implementation is computationally efficient as it introduces only minimal overhead. Furthermore, the coupled model is evaluated in a 4000 year simulation under constant present-day climate forcing and is found to be stable with respect to the ocean and ice sheet spin-up states. The framework deals with heterogeneous spatial grid geometries, varying grid resolutions, and timescales between the ice and ocean component in a generic way; thus, it can be adopted to a wide range of model set-ups.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Publikationsdatum: 2024-02-14
    Beschreibung: Anthropogenic carbon dioxide (CO2) levels are rising to alarming concentrations in earth’s atmosphere, causing adverse effects and global climate changes. In the last century, innovative research on CO2 reduction using chemical, photochemical, electrochemical and enzymatic approaches has been addressed. In particular, natural CO2 conversion serves as a model for many processes and extensive studies on microbes and enzymes regarding redox reactions involving CO2 have already been conducted. In this review we focus on the enzymatic conversion of CO2 to carbon monoxide (CO) as the chemical conversion downstream of CO production render CO particularly attractive as a key intermediate. We briefly discuss the different currently known natural autotrophic CO2 fixation pathways, focusing on the reversible reaction of CO2, two electrons and protons to CO and water, catalyzed by carbon monoxide dehydrogenases (CODHs). We then move on to classify the different type of CODHs, involved catalyzed chemical reactions and coupled metabolisms. Finally, we discuss applications of CODH enzymes in photochemical and electrochemical cells to harness CO2 from the environment transforming it into commodity chemicals.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Publikationsdatum: 2023-02-28
    Beschreibung: The constant increase of geodetic instrumentation over the past decades enables us to not only detect ever smaller tectonic signals but also to monitor their evolution in time and space. We present spatial and temporal slip variations observed on a fault affected by a large, intermediate-field earthquake: the 2015 Mw7.2 Sarez, Central Pamir, earthquake ruptured the sinistral, NE-trending Sarez-Karakul fault system. 120–170 km North of the main rupture, the thin-skinned, E-trending Pamir thrust system bounding the Pamir to the North was co-seismically activated. We derived co-seismic offsets and post-seismic rates observed by two dense, high-rate Global Positioning System (GPS) profiles crossing the Pamir thrust system at different longitudes. The continuous GPS observations of the western profile focus on the dextral, NW-striking Aramkungey fault segment that connects two thrust faults with opposite dip. We compare inter-, co- and post-seismic displacement rates by complementing the continuous data with survey-mode GPS data and East rates derived from satellite radar interferometric displacement time-series. All the GPS stations were shifted toward the epicenter against the direction of the interseismic load with an increased gradient in the Aramkungey fault segment. During the postseismic stage, the fault-parallel and fault-perpendicular rates were affected differently, suggesting gradual re-locking of the Aramkungey fault after its unlocking by right-lateral co-seismic slip.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/article
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  • 99
    Publikationsdatum: 2024-02-07
    Beschreibung: The Los Chocoyos (14.6°N, 91.2°W) supereruption happened ∼75,000 years ago in Guatemala and was one of the largest eruptions of the past 100,000 years. It emitted enormous amounts of sulfur, chlorine, and bromine, with multi‐decadal consequences for the global climate and environment. Here, we simulate the impact of a Los Chocoyos‐like eruption on the quasi‐biennial oscillation (QBO), an oscillation of zonal winds in the tropical stratosphere, with a comprehensive aerosol chemistry Earth System Model. We find a ∼10‐year disruption of the QBO starting 4 months post eruption, with anomalous easterly winds lasting ∼5 years, followed by westerlies, before returning to QBO conditions with a slightly prolonged periodicity. Volcanic aerosol heating and ozone depletion cooling leads to the QBO disruption and anomalous wind regimes through radiative changes and wave‐mean flow interactions. Different model ensembles, volcanic forcing scenarios and results of a second model back up the robustness of our results.
    Materialart: Article , PeerReviewed
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    Format: other
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Publikationsdatum: 2024-02-07
    Beschreibung: The Baltic Sea has a salinity gradient decreasing from fully marine (〉 25) in the west to below 7 in the central Baltic Proper. Habitat-forming and ecologically dominant mytilid mussels exhibit decreasing growth when salinity 〈 11; however, the mechanisms underlying reduced calcification rates in dilute seawater are not fully understood. Both [HCO−3] and [Ca2+] also decrease with salinity, challenging calcifying organisms through CaCO3 undersaturation (Ω≤1) and unfavourable ratios of calcification substrates ([Ca2+] and [HCO−3]) to the inhibitor (H+), expressed as the extended substrate–inhibitor ratio (ESIR). This study combined in situ monitoring of three southwest Baltic mussel reefs with two laboratory experiments to assess how various environmental conditions and isolated abiotic factors (salinity, [Ca2+], [HCO−3] and pH) impact calcification in mytilid mussels along the Baltic salinity gradient. Laboratory experiments rearing juvenile Baltic Mytilus at a range of salinities (6, 11 and 16), HCO−3 concentrations (300–2100 µmol kg−1) and Ca2+ concentrations (0.5–4 mmol kg−1) reveal that as individual factors, low [HCO−3], pH and salinity cannot explain low calcification rates in the Baltic Sea. Calcification rates are impeded when Ωaragonite ≤ 1 or ESIR ≤ 0.7 primarily due to [Ca2+] limitation which becomes relevant at a salinity of ca. 11 in the Baltic Sea. Field monitoring of carbonate chemistry and calcification rates suggest increased food availability may be able to mask the negative impacts of periodic sub-optimal carbonate chemistry, but not when seawater conditions are permanently adverse, as observed in two Baltic reefs at salinities 〈 11. Regional climate models predict a rapid desalination of the southwest and central Baltic over the next century and potentially a reduction in [Ca2+] which may shift the distribution of marine calcifiers westward. It is therefore vital to understand the mechanisms by which the ionic composition of seawater impacts bivalve calcification for better predicting the future of benthic Baltic ecosystems.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
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