ALBERT

Description: Establishing sustainable and responsible speleotourism development is a major challenge and involves complex activities. Adequate theoretical starting point is the application of geoethical values related to the conservation and protection of the caves to be used for touristic purposes. Positive and negative cases of human behaviors towards speleological geoheritage are discussed, in order to highlight what should be done in cave management to avoid malpractices and on what elements could be founded adequate strategies aimed at promoting sustainable speleotourism. This is important to tourism management organizations involved in the promotion of caves and in creating economic opportunities for local populations, while respecting cave ecosystems. Modern cave management must be focused on the protection of the cave ecosystems, finding ways to achieve at the same time an economic development of local communities. But this approach needs the adoption of a geoethical framework of values to be shared by all stakeholders involved so that successful cooperation can be achieved despite differences in interests and expectations. The aim of this paper is to raise the awareness about the need to apply the values of geoethics to speleotourism, stimulating new fields of discussion within the scientific and technical communities involved in studies and activities related to geotourism and geoheritage. The possibilities of developing new ways to manage caves, in order to promote a sustainable socio-economic development of local communities, have to be balanced with the protection of natural environments as much as possible. The proposed theoretical frameworks have the goal to increase the discussion on the best ways of connecting speleotourism to sustainable and responsible cave management, presenting two case studies, and pointing out potential solutions.

Description: Open access funding provided by Istituto Nazionale di Geofisica e Vulcanologia within the CRUI-CARE Agreement

Description: Published

Description: id 73

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: 1TM. Formazione

Description: 2TM. Divulgazione Scientifica

Description: JCR Journal

Description: In this study we present an intercomparison of measurements of very low water vapor column content obtained with a Ground-Based Millimeter-wave Spectrometer (GBMS), Vaisala RS92k radiosondes, a Raman Lidar, and an IR Fourier Transform Spectrometer. These sets of measurements were carried out during the primary field campaign of the ECOWAR (Earth COoling by WAter vapor Radiation) project which took place on the Western Italian Alps from 3 to 16 March, 2007.

Description: Published

Description: 135-138

Description: 1.8. Osservazioni di geofisica ambientale

Description: N/A or not JCR

Description: open

Description: Large earthquakes occurring worldwide have long been recognized to be non Poisson distributed, so involving some large scale correlation mechanism, which could be internal or external to the Earth. Till now, no statistically significant correlation of the global seismicity with one of the possible mechanisms has been demonstrated yet. In this paper, we analyze 20 years of proton density and velocity data, as recorded by the SOHO satellite, and the worldwide seismicity in the corresponding period, as reported by the ISC-GEM catalogue. We found clear correlation between proton density and the occurrence of large earthquakes (M 〉 5.6), with a time shift of one day. The significance of such correlation is very high, with probability to be wrong lower than 10-5. The correlation increases with the magnitude threshold of the seismic catalogue. A tentative model explaining such a correlation is also proposed, in terms of the reverse piezoelectric effect induced by the applied electric field related to the proton density. This result opens new perspectives in seismological interpretations, as well as in earthquake forecast.

Description: Published

Description: 11495

Description: 7T. Variazioni delle caratteristiche crostali e precursori sismici

Description: JCR Journal

Description: We reconstruct the composite dynamics of Mt. Vesuvius volcano in the period 2012–2019 from the study of ground deformation, seismicity, and geofluid (groundwater and fumarolic fluids) circulation and recognize complex spatio-temporal variations in these observables at medium (years) and short (months) time-scales. We interpret the observed patterns as the combined effect of structural changes affecting the volcanic edifice and variations of the dynamics of the hydrothermal system. In particular, we identify a change in the activity state of Mt. Vesuvius. After the activity reached minimum levels in 2014, the centroid of the surface manifestations migrated towards the SE. Episodic variations of co-seismic and aseismic deformation and fluid release, if analysed separately, would likely have been interpreted as pseudo-random oscillations of the background geophysical and geochemical signals. When organised in a comprehensive, multiparametric fashion, they shed light on the evolution of the volcano in 4D (x,y,z, time) space. These inferences play a crucial role in the formulation of civil protection scenarios for Mt. Vesuvius, a high risk, densely urbanized volcanic area which has never experienced unrest episodes in the modern era of instrumental volcanology.

Description: Published

Description: 965

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: This project started in October 2015 with a crazy idea: prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project.

Description: We present early Cretaceous to present paleobathymetric reconstructions and quantitative uncertainty estimates for the South Atlantic, offering a strong basis for studies of paleocirculation, paleoclimate and paleobiogeography. Circulation in an initially salty and anoxic ocean, restricted by the topography of the Falkland Plateau, Rio Grande Ridge and Walvis Rise, favoured deposition of thick evaporites in shallow water of the Brazilian-Angolan margins. This ceased as sea oor spreading propagated northwards, opening an equatorial gateway to shallow and intermediate circulation. This gateway, together with subsiding volcano-tectonic barriers would have played a key role in Late Cretaceous climate changes. Later deepening and widening of the South Atlantic, together with gateway opening at Drake Passage would lead, by mid-Miocene (∼15 Ma) to the establishment of modern-style thermohaline circulation.

Description: Currently there is a scarcity of paleo-records related to the North Atlantic Oscillation (NAO), particularly in East-Central Europe (ECE). Here we report δ15N analysis of guano from a cave in NW Romania with the intent of reconstructing past variation in ECE hydroclimate and examine NAO impacts on winter precipitation. We argue that the δ15N values of guano indicate that the nitrogen cycle is hydrologically controlled and the δ15N values likely reflect winter precipitation related to nitrogen mineralization prior to the growing season. Drier conditions indicated by δ15N values at AD 1848–1852 and AD 1880–1930 correspond to the positive phase of the NAO. The increased frequency of negative phases of the NAO between AD 1940–1975 is contemporaneous with higher δ15N values (wetter conditions). A 4‰ decrease in δ15N values at the end of the 1970’s corresponds to a strong reduction in precipitation associated with a shift from negative to positive phase of the NAO. Using the relationship between NAO index and δ15N values in guano for the instrumental period, we reconstructed NAO-like phases back to AD 1650. Our results advocate that δ15N values of guano offer a proxy of the NAO conditions in the more distant past, helping assess its predictability.

Description: Northward shift of the treeline is expected circum-Arctic and has been observed in a number of locations in response to Arctic warming. The transitional zone between forest and tundra is, therefore, a vulnerable region that requires systematic monitoring. Currently, radar remote sensing is hardly employed in the treeline zone. The unique constellation of the TanDEM-X satellites with its bistatic mode and unprecedented spatial resolution opens new opportunities for monitoring of the treeline zone. We focus on an area near the Trail Valley Creek research basin in the east of the Mackenzie Delta in the Northwest Territories, Canada. The area lies at the northern edge of the treeline zone. Erect vegetation there is characterised by deciduous shrubs up to 3 m in height and isolated patches of sparse coniferous forest. We evaluate the potential of TanDEM-X bistatic data to characterise the structural properties of the forest patches. The TanDEM-X data were acquired during the TanDEM-X Science Phase in 2015, when the effective baseline was large and constant (approximately 540 m). We employ interferometric coherence from multitemporal bistatic pairs and compare it with standard vegetation metrics obtained from airborne LiDAR data. The full-waveform airborne LiDAR data were captured in September 2016, covering an area of about 20 km x 6 km with a point density of approximately 5 points per square meter. LiDAR metrics include vegetation height percentiles and vegetation ratio. The preliminary analysis shows a high agreement between TanDEM-X bistatic coherence and LiDAR vegetation metrics. The relation between coherence and LiDAR metrics, averaged for each forest patch, yields in a strong inverse correlation, varying from -0.81 to -0.88 for different LiDAR metrics. On sub- atch scale, spatial patterns of coherence and LiDAR metrics also show high inverse correspondence. Thus, a pixel-by-pixel comparison gives a first-shot correlation between tree height 99 percentile and coherence from -0.45 to -0.63 for different forest patches. Taking into account the global coverage of multiple bistatic TanDEM-X data acquired for the global digital elevation model, our results provide a basis for the quantification of the treeline properties circum-Arctic.

Description: The Antarctic silverfish (Pleuragramma antarctica) is a critically important forage species with a circumpolar distribution and is unique among other notothenioid species for its wholly pelagic life cycle. Previous studies have provided mixed evidence of population structure over regional and circumpolar scales. The aim of the present study was to test the recent population hypothesis for Antarctic silverfish, which emphasizes the interplay between life history and hydrography in shaping connectivity. A total of 1067 individuals were collected over 25 years from different locations on a circumpolar scale. Samples were genotyped at fifteen microsatellites to assess population differentiation and genetic structuring using clustering methods, F-statistics, and hierarchical analysis of variance. A lack of differentiation was found between locations connected by the Antarctic Slope Front Current (ASF), indicative of high levels of gene flow. However, gene flow was significantly reduced at the South Orkney Islands and the western Antarctic Peninsula where the ASF is absent. This pattern of gene flow emphasized the relevance of large-scale circulation as a mechanism for circumpolar connectivity. Chaotic genetic patchiness characterized population structure over time, with varying patterns of differentiation observed between years, accompanied by heterogeneous standard length distributions. The present study supports a more nuanced version of the genetic panmixia hypothesis that reflects physical-biological interactions over the life history.

Description: With each cell division, phytoplankton create new space for primary colonization by marine bacteria. Although this surface microenvironment is available to all planktonic bacterial colonizers, we show the assembly of bacterial consortia on a cosmopolitan marine diatom to be highly specific and reproducible. While phytoplankton–bacteria interactions play fundamental roles in marine ecosystems, namely primary production and the carbon cycle, the ecological paradigm behind epiphytic microbiome assembly remains poorly understood. In a replicated and repeated primary colonization experiment, we exposed the axenic diatom Thalassiosira rotula to several complex and compositionally different bacterial inocula derived from phytoplankton species of varying degrees of relatedness to the axenic Thalassiosira host or natural seawater. This revealed a convergent assembly of diverse and compositionally different bacterial inocula, containing up to 2071 operational taxonomic units (OTUs), towards a stable and reproducible core community. Four of these OTUs already accounted for a cumulative abundance of 60%. This core community was dominated by Rhodobacteraceae (30.5%), Alteromonadaceae (27.7%), and Oceanospirillales (18.5%) which was qualitatively and quantitatively most similar to its conspecific original. These findings reject a lottery assembly model of bacterial colonization and suggest selective microhabitat filtering. This is likely due to diatom host traits such as surface properties and different levels of specialization resulting in reciprocal stable-state associations.

Description: Antarctic krill (Euphausia superba) are high latitude pelagic organisms which play a key ecological role in the ecosystem of the Southern Ocean. To synchronize their daily and seasonal life-traits with their highly rhythmic environment, krill rely on the implementation of rhythmic strategies which might be regulated by a circadian clock. A recent analysis of krill circadian transcriptome revealed that their clock might be characterized by an endogenous free-running period of about 12–15 h. Using krill exposed to simulated light/dark cycles (LD) and constant darkness (DD), we investigated the circadian regulation of krill diel vertical migration (DVM) and oxygen consumption, together with daily patterns of clock gene expression in brain and eyestalk tissue. In LD, we found clear 24 h rhythms of DVM and oxygen consumption, suggesting a synchronization with photoperiod. In DD, the DVM rhythm shifted to a 12 h period, while the peak of oxygen consumption displayed a temporal advance during the subjective light phase. This suggested that in free-running conditions the periodicity of these clock-regulated output functions might reflect the shortening of the endogenous period observed at the transcriptional level. Moreover, differences in the expression patterns of clock gene in brain and eyestalk, in LD and DD, suggested the presence in krill of a multiple oscillator system. Evidence of short periodicities in krill behavior and physiology further supports the hypothesis that a short endogenous period might represent a circadian adaption to cope with extreme seasonal photoperiodic variability at high latitude.

Description: High Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-tolate Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.

Description: The evolution of past global ice sheets is highly uncertain. One example is the missing ice problem during the Last Glacial Maximum (LGM, 26 000-19 000 years before present) – an apparent 8-28 m discrepancy between far-field sea level indicators and modelled sea level from ice sheet reconstructions. In the absence of ice sheet reconstructions, researchers often use marine δ 18 O proxy records to infer ice volume prior to the LGM. We present a global ice sheet reconstruction for the past 80 000 years, called PaleoMIST 1.0, constructed inde- pendently of far-field sea level and δ 18 O proxy records. Our reconstruction is compatible with LGM far-field sea-level records without requiring extra ice volume, thus solving the missing ice problem. However, for Marine Isotope Stage 3 (57 000-29 000 years before present) - a pre-LGM period - our reconstruction does not match proxy-based sea level reconstructions, indicating the relationship between marine δ 18 O and sea level may be more complex than assumed.

Description: Lake Baikal is inhabited by more than 300 endemic amphipod species, which are narrowly adapted to certain thermal niches due to the high interspecific competition. In contrast, the surrounding freshwater fauna is commonly represented by species with large‐scale distribution and high phenotypic thermal plasticity. Here, we investigated the thermal plasticity of the energy metabolism in two closely‐related endemic amphipod species from Lake Baikal (Eulimnogammarus verrucosus; stenothermal and Eulimnogammarus cyaneus; eurythermal) and the ubiquitous Holarctic amphipod Gammarus lacustris (eurythermal) by exposure to a summer warming scenario (6–23.6 °C; 0.8 °C d−1). In concert with routine metabolic rates, activities of key metabolic enzymes increased strongly with temperature up to 15 °C in E. verrucosus, whereupon they leveled off (except for lactate dehydrogenase). In contrast, exponential increases were seen in E. cyaneus and G. lacustris throughout the thermal trial (Q10‐values: 1.6–3.7). Cytochrome‐c‐oxidase, lactate dehydrogenase, and 3‐hydroxyacyl‐CoA dehydrogenase activities were found to be higher in G. lacustris than in E. cyaneus, especially at the highest experimental temperature (23.6 °C). Decreasing gene expression levels revealed some thermal compensation in E. cyaneus but not in G. lacustris. In all species, shifts in enzyme activities favored glycolytic energy generation in the warmth. The congruent temperature‐ dependencies of enzyme activities and routine metabolism in E. verrucosus indicate a strong feedback‐ regulation of enzymatic activities by whole organism responses. The species‐specific thermal reaction norms reflect the different ecological niches, including the spatial distribution, distinct thermal behavior such as temperature‐dependent migration, movement activity, and mating season.

Description: Central Europe has experienced a severe drought almost every April for the last 14 years consecutively, driven by record high temperatures, low flows, high evapotranspiration, and high soil moisture deficit. The dynamic of this recent and recurrent mid-spring dryness is not yet understood. Here we show that the period 2007â€``2020 was characterized by a reduction of ~50% of the usual April rainfall amount over large areas in central Europe. The precipitation deficit and the record high temperatures were triggered by a multiyear recurrent high-pressure system centered over the North Sea and northern Germany and a decline in the temperature gradient between the Arctic region and the mid-latitudes, which diverted the Atlantic storm tracks northward. From a long-term perspective, the precipitation, temperature, and soil moisture anomalies observed over the last 14 years have reached the highest amplitudes over the observational record. Our study provides an in-depth analysis of the hydroclimate extremes in central Europe over the last 140 years and their atmospheric drivers, enabling us to increase our dynamical understating of long-term dry periods, which is vital to enhance forecasting and mitigation of such events.

Description: Floating ice shelves are the Achilles’ heel of the Antarctic Ice Sheet. They limit Antarctica’s contribution to global sea level rise, yet they can be rapidly melted from beneath by a warming ocean. At Filchner-Ronne Ice Shelf, a decline in sea ice formation may increase basal melt rates and accelerate marine ice sheet mass loss within this century. However, the understanding of this tipping-point behavior largely relies on numerical models. Our new multi-annual observations from five hot-water drilled boreholes through Filchner-Ronne Ice Shelf show that since 2015 there has been an intensification of the density-driven ice shelf cavity-wide circulation in response to reinforced wind-driven sea ice formation in the Ronne polynya. Enhanced southerly winds over Ronne Ice Shelf coincide with westward displacements of the Amundsen Sea Low position, connecting the cavity circulation with changes in large-scale atmospheric circulation patterns as a new aspect of the atmosphere-ocean-ice shelf system.

Description: The thecosome pteropods Limacina helicina and L. retroversa are important contributors to the zooplankton community in high-latitude environments but little is known about their distribution and life cycle under polar conditions. We collected the early life stages (〈 1 mm) of the thecosome population in 2012 and 2013 at a bi-weekly to monthly resolution in fjord highly influenced by Arctic waters as well as Atlantic inflows (Adventfjorden, Svalbard, 78°N), together with environmental parameters. L. retroversa only occurred episodically, in association with the inflow of Atlantic water, with low numbers and random size distributions. This suggests that this boreal species does not fulfill its life cycle in Adventfjorden. In contrast, young specimens of L. helicina were present during the entire study. Veligers hatched in late summer/autumn and measured 0.14 mm on average. They grew with rates of 0.0006 mm day− 1 over the 10–11 months of development. Only thereafter, growth accelerated by one order of magnitude and maximal rates were reached in autumn (0.0077 mm day− 1). Our results indicate that L. helicina reaches a size of 1 mm after approximately 1.5 years in Adventfjorden. We therefore suggest that L. helicina overwinters the first year as a small juvenile and that it needs at least 2 years to reach an adult size of 5 mm in Adventfjorden. This reveals an complex and delicate aspect of the life-cycle of L. helicina and further research is needed to determine if it makes the population especially vulnerable towards climate changes.

Description: Slope failure like in the Hinlopen/Yermak Megaslide is one of the major geohazards in a changing Arctic environment. We analysed hydroacoustic and 2D high-resolution seismic data from the apparently intact continental slope immediately north of the Hinlopen/Yermak Megaslide for signs of past and future instabilities. Our new bathymetry and seismic data show clear evidence for incipient slope instability. Minor slide deposits and an internally-deformed sedimentary layer near the base of the gas hydrate stability zone imply an incomplete failure event, most probably about 30000 years ago, contemporaneous to or shortly after the Hinlopen/Yermak Megaslide. An active gas reservoir at the base of the gas hydrate stability zone demonstrate that over-pressured fluids might have played a key role in the initiation of slope failure at the studied slope, but more importantly also for the giant HYM slope failure. To date, it is not clear, if the studied slope is fully preconditioned to fail completely in future or if it might be slowly deforming and creeping at present. We detected widespread methane seepage on the adjacent shallow shelf areas not sealed by gas hydrates.

Description: Vast parts of Arctic Siberia are underlain by ice-rich permafrost, which is exposed to different processes of degradation due to global warming. Thermal erosion as a key process for landscape degradation in these regions causes the recent reactivation and formation of new landforms like thermo-erosional valleys and gullies. However, a statistical assessment about the decisive factors and the locations most susceptible to this phenomenon is still missing. We investigated the influence of different environmental parameters on the occurrence of recently observed thermal erosion using a GIS-based approach and statistical modeling by logistic regression. The study site is located on an island within the Arctic Lena River Delta and is mainly composed of ice- and organic-rich deposits of the Yedomatype Ice Complex. Field surveys and mapping on the basis of high-resolution remotely sensed data revealed that thermal erosion occurs predominantly i) on very steep slopes along the margins of the island, ii) in the upper reaches of deeply incised valleys and iii) in gullies. In order to detect the regulation factors for those thermo-erosional landforms, we derived several environmental parameters using a high-resolution DEM and satellite imagery. We chose a stepwise logistic regression approach to reduce the full set of potential parameters. This approach allowed the selection of a parsimonious model, i.e. a best-fit model using as few parameters as possible. The parameters Contribution of warm open surface water, Relief ratio, Direct solar radiation and Snow accumulation turned out to be the decisive factors for thermal erosion. Uncertainties in the model due to sampling and model selection were valuated both statistically and spatially through the generation of 100 models. Receiver Operating Characteristics (ROCs) were used to validate the spatial predictive capability of each model run. The consensus map as the median of all 100 susceptibility models represents the final susceptibility map. The agreement between mapped and predicted erosion turned out to be generally very high within the study site, confirmed by an Area under the ROC curve (AUC) of 0.957 for the consensus map. The variability of predicted erosion probabilities between the single models is about four percentage points per cell within the study site and thus, very low. We attributed the slight mismatches between observed and predicted erosion to the generation of the explanatory environmental parameters and the modeling approach. Model results seem promising for the spatial prediction of susceptible sites for thermal erosion and, thus, could be a tool to explain the geomorphic forming in this rapidly changing environment. As these results are based on a single case study, future investigation should focus on the transferability of the model by applying an external validation on other sites with comparable environmental conditions.

Description: The Arctic is affected by rapid climate change, which has substantial impact on permafrost regions and the world as a whole (Raynolds et al., 2014). In the last 30 years Arctic temperatures have risen 0.6 °C per decade, twice as fast as the global average (AMAP, 2011, Schuur et al., 2015). This in turn leads to the degradation of ice-rich permafrost (Grosse et al., 2011) and modifies drainage, increases mass movements and alters landscapes (Nelson et al., 2001; Anisimov et al., 2007, Romanovsky et al., 2010b). Although permafrost regions are not densely populated, their economic importance has increased substantially in recent decades. This is related to the abundance of natural resources in the polar region and improved methods of hydrocarbon extraction, transportation networks to population centers and engineering maintenance systems (Nelson et al., 2002; Mazhitova et al., 2004, AMAP, 2011). The Yamal Peninsula in North West Siberia is experiencing some of the most rapid land cover and land use changes in the Arctic due to a combination of climate change and gas development in one of the most extensive industrial complexes (Kumpula et al., 2006; Walker et al., 2011; Leibman et al., 2015). Specific geological conditions with nutrient-poor sands, massive tabular ground ice and extensive landslides intensify these impacts (Walker et al., 2011). The combination of high natural erosion potential and anthropogenic influence cause extremely intensive rates of erosion (Gubarkov et al., 2014). A considerable amount of recent work has focused on the effects of industrial development to ecological and social implications (Forbes, 1999; Kumpula et al., 2010; Walker et al., 2011). This study aims at exemplarily investigating a region that has been affected by natural and anthropogenic large-scale disturbances within a very short period. The construction of the world’s northernmost railway for the Bovanenkvo Gas Field was finished in 2010. In addition the region experienced an extremly warm and wet summer in 2012. The objectives of this study are • to map surface disturbances of central Yamal between 2010 and 2013/2015 based on highresolution satellite imagery and on the most recent SPOT5-TAKE-5 imagery in 2015, • to quantify natural and anthropogenic impacts in terms of permafrost degradation, • to use meteorological data from the nearest climate station (Marre Sale, Yamal) and from reanalyses climate data on air temperature and precipitation.

Description: In order to understand the influence of surrounding catchment characteristics on the CDOM concentration different types of surface waters in the Lena river delta region were investigated regarding their geochemical composition. The Lena River Delta consists of three geomorphological main terraces that differ in their relief, hydrological and cryolithological characteristics, which possibly influences the content of dissolved substances in their associated water bodies and in the neighboring river branches. During summer seasons of 2013-2014 water samples were collected from river branches as well as from lakes and melt-water streams on the first and the third main terraces and analyzed them for concentrations of colored dissolved organic matter (CDOM), dissolved organic carbon (DOC), and main and trace elements (Na, K, Mg, Ca, HCO3, F, Cl, SO4, Fe, Si, Sr). This type of research was carried out for surface waters in the Lena delta region for the first time. Statistical analysis revealed several correlations between CDOM, DOC and mineral ions. For example, R-squared (the coefficient of determination) for CDOM and Cl and for CDOM and Na in Lena River branches were 0.52 and 0.51, respectively. Correlation between CDOM and F was also found for melt-water streams from the Ice Complex (third terrace) (R-squared = 0.5). Analysis of the relationship between CDOM and DOC showed strong correlation of these parameters for lakes (R-squared = 0.98) and lower correlation for river branches (R- squared = 0.48). In streams formed by the thawing of Ice Complex deposits on the third terrace was found the highest values of CDOM and DOC, but a correlation between them was not observed. A clear dependency was found out between CDOM and DOC correlation and the location of lakes on different terraces with specific permafrost conditions. A stronger correlation was observed for the lakes located on the third terrace (Ice Complex) compared to lakes located on the first terrace (Samoylov Island). Usually, lakes on the first terrace get flooded by river waters during spring, whereas lakes of the third terrace are not affected by river water inflow and have more stable conditions. The Lena delta branches are influenced by differing surrounding conditions, therefore CDOM and DOC concentrations change during summer season and did not show strong correlations.

Description: Preface The Local Organizing Committee (LOC) of the Eleventh International Conference on Permafrost (ICOP2016) is excited about the breadth and the quality of the abstracts submitted for this conference. It was the first time that ICOP topical sessions were not set by the organizing committee in a top-down manner. Instead, sessions were submitted from the bottom-up by groups of researchers and engineers from all over the world. This grassroots effort prompted the submission of many innovative topics covering the full range of modern permafrost research. It also facilitated not only the engagement of the core permafrost community, but also of science disciplines traditionally less involved in ICOPs. In total, 51 session proposals were received by the LOC. These were submitted by up to three conveners including at least one early career researcher from the Permafrost Young Researchers Network (PYRN). After the evaluation process by the International Scientific Committee (ISC) and the LOC, including the addition of strategic topics and the combination of sessions with thematic overlap, 40 topical sessions were eventually opened for abstract submission. There was yet another novelty compared to previous ICOPs: the submission of contributions was not divided into abstracts and papers, in favor of a quicker and uniform review process allowing for the submission deadline to be set closer to the conference. This opened the possibility for authors to present recent results in the rapidly evolving field of permafrost research. Abstracts of up to 3000 words were allowed, either plain or formatted with subheadings, and including one figure, table or equation. We received the extraordinary number of 980 abstracts. This number varied between 79 and 0 among sessions, which led to a further consolidation into the final set of 32 sessions presented in this abstract volume. Abstract evaluation was placed in the hands of the session conveners. The vast majority of abstracts (97 %) was deemed eligible to be accepted for presentation during the conference, either immediately or after revision by the authors. The reduced number of abstracts presented in this volume is mostly due to the inability of travelling to the conference for some authors. We are very delighted that the modified procedures for the compilation of the scientific conference program proved so successful and wish to extend our gratitude to the session conveners and ISC members for their tremendous efforts and great support in compiling such a high-quality program. We also wish to thank Hans-Wolfgang Hubberten, Lydia Polakowski, Matthias Fuchs, Ingmar Nitze, Samuel Stettner, Karina Schollaen, Hugues Lantuit, and Guido Grosse for their technical help in the final editing phase of this abstract volume. Frank Günther and Anne Morgenstern

Description: Nowadays due to climate change the interest to the hydrological processes in the permafrost affected regions is growing. Permafrost soil is important carbon pool and thawing can cause the increase of carbon outflow from Arctic river basins. During Russian-German expeditions Lena-2012 and 2013 some measurements were carried out on the catchment of the Fish Lake on Samoylovsky Island in the Lena River delta. Fish Lake is a thermokarstpolygonal lake, and the landscape of its catchment is typical for the Arctic polygonal tundra. These measurements were done in order to study the DOC income to the lake from an active layer of the catchment. Measurements of the DOC concentration in the pore water and the depth of seasonal thawing were made at 21 points in the 1,52 sq km catchment. The points were selected in different parts of the polygons to consider the heterogeneity of the landscape. Samples for DOC were analyzed in the field using a Spectro::lyser probe and in the lab with a Shimadzu TOC-L probe. In August the depth of the active layer was between 20 and 60 cm: 20-30 cm on the polygon rims, 30-60 cm in the polygon centers and near the lake. During the month when the measurements were made the depth increased by 10-15. For August the DOC concentration in the pore water of the active layer was 8-51 mg/l, for July – 5-30 mg/l, which correlates with the results of other researches in Arctic region. The changes in DOC concentration in pore water for the different thaw depth were examined. Maximum was observed on the depth 35-40 cm for July and 45-55 cm for August. So, for the same depth the variance in the concentration was the most significant. The DOC flux to the Fish Lake was calculated using the mean measured concentration and water runoff from the catchment (Ogorodnikova, 2011). The DOC daily flux to the lake is evaluated as about 0,8 kg per day and the flow rate is 0,5 kg/ km2*day, which is in ten time less than for the lake catchment of southern areas (Moore, 2003). Prolongation of field measurements is necessary for reasons clarifying and for better understanding of DOC flux formation processes under different conditions including thawing increase.

Description: Previous studies have shown that arctic river delta systems are areas of accumulation of geochemical substances at the sea-river mixing zone. In the Lena River Delta our previous work shows the tendencies of water runoff redistribution changes and heterogeneity of suspended supply distribution along the delta branches, accumulation and erosion zone in the different parts of the delta. Nevertheless, the processes of geochemical flow transformation in the subaerial deltas are so far underestimated. In order to close this gap, we sampled water, suspended and bottom sediments in the Lena River Delta in the summer seasons of 2010 and 2014. Most of the sampling points were tight to the profiles of hydrological measurements held in the delta and highlighted in Fedorova et al. [2015]. The results show that geochemical transformation of the Lena River runoff is taking place in the delta. The most active time for the transformation is the summer season due to the activity of sediment accumulation and biogeochemical processes. Hydrological conditions in the delta affect also its hydrogeochemical characteristics. Furcation of the delta branches affects the hydrodynamic conditions of different delta areas. The factors influencing the geochemical characteristics of the delta were identified on the base of geochemical indexes approach applied to sediments and statistical factor analysis. Based on geochemical indexes (Al/Na, Si/Al, Fe/Mn and Fe/Al ratios) similar conditions were determined for the main branch of the Lena, the upstream parts of Bykovskaya and Tumatskaya branches and in Olenekskaya branch near Chay-Tumus. Despite of high runoff the branches are characterized by element accumulation, which can be explained by decreasing of flow turbulence and specificity redox conditions in these areas. Bottom sediments are one of the most important indicators of geochemical transformation processes. The results of statistical factor analysis show three main factors for formation of the these geochemical conditions in the delta: 1. the general water flow of the Lena River, which is influenced by the lithogenous base of the river catchment, 2. the cryogenic condition of the Lena Delta (permafrost degradation processes and cryogenic weathering) and 3. biogeochemical transformation during redistribution of chemical water components , suspended matter and bottom sediments. Acknowledgements The research was supported by grant No. 14-05-00787 A of Russian Foundation for Basic Research References Fedorova, I.; Chetverova, A.; Bolshiyanov, D.; Makarov, A.; Boike, J.; Heim, B.; Morgenstern, A.; Overduin, P. P.; Wegner, C.; Kashina, V.; Eulenburg, A.; Dobrotina, E. and Sidorina, I. [2015]: Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations. Biogeosciences, 12(2):345–363, doi:10.5194/bg-12-345-2015.

Description: Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 〉 0.96, p 〈 0.0001), suggesting a link to organic matter degradation. This inference was supported by the positive correlation (R2 〉 0.95, p 〈 0.0001) between the net production of FDOM and the modeled degradation rates of particulate organic carbon sulfate reduction. The production of FDOM was more pronounced in a shallow shelf site S1 with a total net production ranging from 17.9 to 62.3 RU for different FDOM components above the SMTZ depth of ca. 4.1 mbsf, which presumably underwent more accumulation of particulate organic matter than the other three deeper sites. The sediments were generally found to be the sources of CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.

Description: The Lena River delta is one of the hydrologically entertaining objects. Hundreds channels and thousands lakes as well as thawing ice complex and permafrost active layer dynamic allow to investigate spatial-temporal coherence of different scale hydrological processes. During 15 years Russian-German scientific collaboration on hydrological, hydrochemical and hydrobiological studies have been operated on different water objects for cause-effect relation of large and specific micro processes indication. Transient liquid-frozen water phase change is significant not only for active layer runoff forming but also for hydrochemical and biological specific. Thus, maximum of DOC is in the overlaying soil layer than permafrost border [Bobrova et al., 2013]. It could be used for modeling of runoff forming and biological activity estimation. Measured temperature of lacustrine bottom sediment of one thermokarst lake on Samoylov Island shows maximal volume 3,7 °C on 1,75 cm beneath water-sediment border [Skorospekhova, 2015]. It is also can be interpreted as biological processes activity, for example, organic material destruction with additional heating. It could be observed more detail and can be used for modeling of a lake thermic regime. Hydrobiological specificity shows similarity of species in the channels and lakes, poorness of biodiversity, especially in big channel; only stagnant in summer season Bulkurskaya channel has more zooplankton species in four times than the main river channel [Nigamatzyanova et al., 2015]. Decline of water turbidity from the delta top to channel edges is about 5-8 times [Charkin et al., 2009]. Considerable turbidity increase is formed according to permafrost thawing and can reach 500 g l-1 including high concentration of carbon and biogenic elements. Thermokarst lake degradation [Morgenstern et al., 2011] plays also an important role for permafrost hydrology in the delta. Outflow from an ice complex forms a high local suspended supply in adjacent river branches and influences on biological processes consequently [Dubinenkov et al., 2015]. Underestimated effect of water and sediment discharge increase in the middle part of river branches had been marked [Fedorova et al., 2015]. Head flux of the large Lena River forms taliks under channels with more sophisticated affect in the shoreline zone of the Laptev Sea due to aquifer dynamic and mixing of fresh and salt water. Talik effect on hydrology and sedimentation (and suspended material transformation) in the central part of the delta is currently carried out according to geophysical and hydrogeological methods. First field measurements are planned to be done in April 2016 and results will be presented in the ICOP 2016. The studies have been done with support of RFBR grant 14-05-00787 and 15-35-50949, in the framework of Russian-German projects “ CarboPerm” and “Scientific station “Samoylov Island”. The project for both SPBU and DFG funding had also applied for field and scientific investigation as well. References Bobrova, O.; Fedorova, I.; Chetverova, A.; Runkle, B. and Potapova, T. Input of Dissolved Organic Carbon for Typical Lakes in Tundra Based on Field Data of the Expedition Lena–2012. In Proceedings of the 19th International Northern Research Basins Symposium and Workshop, Southcentral Alaska, USA – August 11–17, 2013, 2013. Charkin, A.N.; Dudarev, O.V.; Semiletov, I.P.; Fedorova, I.; Chetverova, A.A.; J., Vonk; Sanchez- Garcia, L.; Gustafsson, ö. and Andersson, P. edimentation in the System of the Delta Lena River - the South Western Part of Buor-Haya Gulf (the Laptev Sea). In The 16th International Symposium on Polar Sciences. Incheon, Korea. 2009, 2009. Dubinenkov, I.; Flerus, R.; Schmitt-Kopplin, P.; Kattner, G. and Koch, B.P. [2015]: Origin-specific molecular signatures of dissolved organic matter in the Lena Delta. Biogeochemistry, 123(1):1–14, doi:10.1007/s10533-014-0049-0. Fedorova, I.; Chetverova, A.; Bolshiyanov, D.; Makarov, A.; Boike, J.; Heim, B.; Morgenstern, A.; Overduin, P. P.; Wegner, C.; Kashina, V.; Eulenburg, A.; Dobrotina, E. and Sidorina, I. [2015]: Lena delta hydrology and geochemistry: long-term hydrological data and recent field observations. Biogeosciences, 12(2):345–363, doi:10.5194/bg-12-345-2015. Morgenstern, A.; Grosse, G.; Günther, F.; Fedorova, I. and Schirrmeister, L. [2011]: Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta. The Cryosphere, 5(4):849–867, doi:10.5194/tc-5-849-2011. Nigamatzyanova, G.; Frolova, L.; Chetverova, A. and Fedorova, I. Hydrobiological investigation of branches of the Lena River edge zone. In Uchenye Zapiski Kazanskogo Universiteta, Seriya Estestvennye Nauki. 2015. in Russian. Skorospekhova, T. Report of a spring campaign of the expedition “Lena 2015”. AARI’s library stock, 2015.

Description: Stable water isotope records from Antarctica are key for our understanding of Quaternary climate variations. However, the exact quantitative interpretation of these important climate proxy records in terms of surface temperature, ice sheet height and other climatic changes is still a matter of debate. Here we report results obtained with an atmospheric general circulation model equipped with water isotopes, run at a high-spatial horizontal resolution of one-by-one degree. Comparing different glacial maximum ice sheet reconstructions, a best model data match is achieved for the PMIP3 reconstruction. Reduced West Antarctic elevation changes between 400 and 800 m lead to further improved agreement with ice core data. Our modern and glacial climate simulations support the validity of the isotopic paleothermometer approach based on the use of present-day observations and reveal that a glacial ocean state as displayed in the GLAMAP reconstruction is suitable for capturing the observed glacial isotope changes in Antarctic ice cores.

Description: A dominant Antarctic ecological paradigm suggests that winter sea ice is generally the main feeding ground for krill larvae. Observations from our winter cruise to the southwest Atlantic sector of the Southern Ocean contradict this view and present the first evidence that the pack-ice zone is a food-poor habitat for larval development. In contrast, the more open marginal ice zone provides a more favourable food environment for high larval krill growth rates. We found that complex under-ice habitats are, however, vital for larval krill when water column productivity is limited by light, by providing structures that offer protec- tion from predators and to collect organic material released from the ice. The larvae feed on this sparse ice-associated food during the day. After sunset, they migrate into the water below the ice (upper 20 m) and drift away from the ice areas where they have previously fed. Model analyses indicate that this behaviour increases both food uptake in a patchy food environment and the likelihood of overwinter transport to areas where feeding conditions are more favourable in spring.

Description: There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause build-up of overpressure at the base of the gas hydrate stability zone. Resulting hydro-fracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth.

Description: Arctic tundra landscapes are composed of a complex mosaic of patterned ground features, varying in soil moisture, vegetation composition, and surface hydrology over small spatial scales (10–100 m). The importance of microtopography and associated geomorphic landforms in influencing ecosystem structure and function is well founded, however, spatial data products describing local to regional scale distribution of patterned ground or polygonal tundra geomorphology are largely unavailable. Thus, our understanding of local impacts on regional scale processes (e.g., carbon dynamics) may be limited. We produced two key spatiotemporal datasets spanning the Arctic Coastal Plain of northern Alaska (~60,000 km2) to evaluate climate-geomorphological controls on arctic tundra productivity change, using (1) a novel 30m classification of polygonal tundra geomorphology and (2) decadal-trends in surface greenness using the Landsat archive (1999–2014). These datasets can be easily integrated and adapted in an array of local to regional applications such as (1) upscaling plot-level measurements (e.g., carbon/energy fluxes), (2) mapping of soils, vegetation, or permafrost, and/or (3) initializing ecosystem biogeochemistry, hydrology, and/or habitat modeling.

Description: The field of Arctic sea ice prediction on “weather time scales” is still in its infancy with little existing understanding of the limits of predictability. This is especially true for sea ice deformation along so-called Linear Kinematic Features (LKFs) including leads that are relevant for marine operations. Here the potential predictability of the sea ice pack in the wintertime Arctic up to ten days ahead is determined, exploiting the fact that sea ice-ocean models start to show skill at representing sea ice deformation at high spatial resolutions. Results are based on ensemble simulations with a high-resolution sea ice-ocean model driven by atmospheric ensemble forecasts. The predictability of LKFs as measured by different metrics drops quickly, with predictability being almost completely lost after 4–8 days. In contrast, quantities such as sea ice concentration or the location of the ice edge retain high levels of predictability throughout the full 10-day forecast period. It is argued that the rapid error growth for LKFs is mainly due to the chaotic behaviour of the atmosphere associated with the low predictability of near surface wind divergence and vorticity; initial condition uncertainty for ice thickness is found to be of minor importance as long as LKFs are initialized at the right locations.

Description: Antarctic krill (Euphausia superba) is a key species in Southern Ocean ecosystem where it plays a central role in the Antarctic food web. Available information supports the existence of an endogenous timing system in krill enabling it to synchronize metabolism and behavior with an environment characterized by extreme seasonal changes in terms of day length, food availability, and surface ice extent. A screening of our transcriptome database “KrillDB” allowed us to identify the putative orthologues of 20 circadian clock components. Mapping of conserved domains and phylogenetic analyses strongly supported annotations of the identi ed sequences. Luciferase assays and co-immunoprecipitation experiments allowed us to de ne the role of the main clock components. Our ndings provide an overall picture of the molecular mechanisms underlying the functioning of the endogenous circadian clock in the Antarctic krill and shed light on their evolution throughout crustaceans speciation. Interestingly, the core clock machinery shows both mammalian and insect features that presumably contribute to an evolutionary strategy to cope with polar environment’s challenges. Moreover, despite the extreme variability characterizing the Antarctic seasonal day length, the conserved light mediated degradation of the photoreceptor EsCRY1 suggests a persisting pivotal role of light as a Zeitgeber.

Description: Arctic tundra ecosystems have experienced unprecedented change associated with climate warming over recent decades. Across the Pan-Arctic, vegetation productivity and surface greenness have trended positively over the period of satellite observation. However, since 2011 these trends have slowed considerably, showing signs of browning in many regions. It is unclear what factors are driving this change and which regions/landforms will be most sensitive to future browning. Here we provide evidence linking decadal patterns in arctic greening and browning with regional climate change and local permafrost-driven landscape heterogeneity. We analyzed the spatial variability of decadal-scale trends in surface greenness across the Arctic Coastal Plain of northern Alaska (~60,000 km²) using the Landsat archive (1999–2014), in combination with novel 30 m classifications of polygonal tundra and regional watersheds, finding landscape heterogeneity and regional climate change to be the most important factors controlling historical greenness trends. Browning was linked to increased temperature and precipitation, with the exception of young landforms (developed following lake drainage), which will likely continue to green. Spatiotemporal model forecasting suggests carbon uptake potential to be reduced in response to warmer and/or wetter climatic conditions, potentially increasing the net loss of carbon to the atmosphere, at a greater degree than previously expected.

Description: Thermo-erosional landforms (valleys, gullies) and their associated streams are the main connecting pathways between inland permafrost areas and rivers and coasts. Surface and ground waters are routed along these streams, which transport particulate and dissolved matter from the catchments to the rivers and coastal waters. Regions of ice-rich permafrost, such as the Yedoma-type Ice Complex, are not only characterized by a high abundance of thermo-erosional landforms, which formed during the Holocene, but are subject to extensive degradation under current arctic warming by processes such as thermal erosion, thermokarst, and active layer deepening. In the Siberian Lena River Delta Yedoma-type Ice Complex deposits occur on insular remnants of a Late-Pleistocene accumulation plain that has been dissected by Lena River branches and degraded by thermal erosion and thermokarst during the Holocene. This region serves as suitable exemplary study area for estimating the contribution of 1) different permafrost degradation landforms to the export of water and dissolved matter from Yedoma-type Ice Complex to the river and 2) active degradation of old permafrost versus seasonal runoff from the surface and active layer. In the summers of 2013 and 2014 we sampled surface and soil waters from streams and their watersheds in Yedomatype Ice Complex landscapes of the Lena River Delta and analyzed them for a range of hydrogeochemical parameters including electrical conductivity (EC), dissolved organic carbon (DOC) and stable isotopic composition. The sampling sites were spread over an E-W-extent of about 150 km and are characterized by very diverse geomorphological and hydrological situations in terms of distance to the river branches, catchment size, discharge, degree of thermo-erosional activity, and connection to other permafrost degradation landforms (thermokarst lakes and basins). Three key sites were sampled three and four times from June to September 2013 and 2014, respectively, in order to analyze intra-seasonal changes. The results show large variances in EC (25 to 1205 μS/cm), DOC concentrations (2.9 to 119.0 mg/l), �18O (-29.8 to -14.6 ‰ vs. SMOW), and �D (-228.9 to -117.9‰ vs. SMOW) over the whole dataset, with distinct characteristics in the parameter combination for different degradation landform and water types. The temporal variability at the repeatedly sampled sites is low, which implies that there is not much change in the processes that determine the water composition throughout the summer season. By comparing differences in surface water chemistry between flow path systems that tap into varying amounts of source water (precipitation, surface and ground water, ground ice) and have differing residence times and extents, we explore the effect of future changes in thermokarst and thermo-erosional intensity and resulting changes in flow path hydrogeochemistry for thermoerosional features draining ice-rich permafrost.

Description: The effect of climate warming on the degradation of permafrost in Arctic coastal lowlands and associated hydrological and biogeochemical processes varies between different types of permafrost deposits. The Lena River Delta consists of three geomorphological main terraces that differ in their genesis and stratigraphic, cryological, geomorphological and hydrological characteristics. The third terrace was formed during the late Pleistocene and consists mainly of Yedoma-type Ice Complex deposits, whereas the first terrace has formed during the Holocene by deltaic processes. Permafrost degradation on both terraces releases dissolved organic carbon (DOC) to thermokarst lakes and via streams DOC gets transported to the Lena River channels and the Arctic Ocean. This presentation shows 1. differences in the surface water chemistry between the first terrace and the Yedoma Ice Complex and their landforms, 2. analyses of the temporal variability of DOC during the summer, and 3. an estimation of summer DOC flux for the considered catchment of about 6.45 km2. Between June and September 2013 and 2014, respectively summer surface water and soil water samples were collected in a small catchment in the south of Kurungnakh Island in the central Lena River Delta. This catchment covers the first terrace as well as the Yedoma Ice Complex and is characterized by thermokarst lakes and streams on both terraces. Two weirs were installed in the main stream along the drainage flow path to continuously measure discharge during summer 2013. We divided the study area into landscape units and compared pH, electrical conductivity, stable isotopic composition and DOC concentrations between units and between terraces. The considered landscape units are streams and thermokarst lakes on Yedoma Ice Complex and on the first terrace, Yedoma uplands, streams, which are fed by the Ice Complex, a relict lake on the first terrace and the Olenyokskaya Channel, a main branch of the Lena River. DOC concentrations in the landscape units on Yedoma Ice Complex ranged between 3.5 mg L-1 (streams) and 52.5 mg L−1 (soilwater of Yedoma uplands) and on the first terrace between 2.8 mg L−1 (streams) and 15.6 mg L−1 (relict lake). The electrical conductivity on Yedoma Ice Complex ranged between 35 μS cm-1 (soilwater of Yedoma uplands) and 151 μS cm−1 (streams) and on the first terrace between 54 μS cm−1 (streams and relict lake) and 140 μS cm−1 (streams). δ18O values on Yedoma Ice Complex and first terrace ranged between -22.4 ‰ (soilwater of Yedoma uplands) and -16.4 ‰ (streams) and between -20.4 ‰and -14.7 ‰ (streams), respectively. δD ranged between -165.6 ‰ (soilwater of Yedoma uplands) and 125.5 ‰ (streams, which are fed by the Ice Complex) and between -160.8 ‰ and -119.4 ‰ (streams). Source waters on the Yedoma Ice Complex had higher DOC concentrations and lower electrical conductivity than Yedoma Ice Complex thermokarst lakes and the drainage flow path. This suggests that more labile organic carbon, perhaps derived from permafrost degradation on the Yedoma Ice Complex, enriches the lake but is removed from the lake, for example, by mineralization in the water column. Along the drainage flow path no further decrease of DOC concentration was observed, despite increasing discharge from weir 1 at the beginning of the flow path to almost two and a half times at weir 2 at the end of the flow path, and despite decreasing discharge during the measuring period from 1814 m3 d−1 in the end of July to 199 m3 d−1 in the end of August for weir 1 and from 2819 m3 d−1 in the end of July to 567 m3 d−1 in the end of August for weir 2. The temporal variability of DOC concentration during the sampling periods was low. In 2013 one sample site of soil water collection fluctuated slightly in August between 10.5 mg L−1 and 13.3 mg L−1, whereas the remaining landscape units showed no temporal variability. In 2014 the DOC concentration of the relict lake on the first terrace decreased from July (13.5 mg L−1) to September (11.1 mg L−1). Otherwise there were no changes in DOC concentration in the remaining landscape units. DOC measurements of the Olenyokskaya Channel show a decrease in DOC concentration from 12.4 mg L−1 in June to 7.6 mg L−1 in September. Using discharge data of 2013 a summer DOC flux of about 220 kg in 29 days for the study site above weir 2 with an area of 6.45 km2 was calculated.

Description: Antarctic krill (Euphausia superba)—one of the most abundant animal species on Earth—exhibits a five to six year population cycle, with oscillations in biomass exceeding one order of magnitude. Previous studies have postulated that the krill cycle is induced by periodic climatological factors, but these postulated drivers neither show consistent agreement, nor are they supported by quantitative models. Here, using data analysis complemented with modelling of krill ontogeny and population dynamics, we identify intraspecific competition for food as the main driver of the krill cycle, while external climatological factors possibly modulate its phase and synchronization over large scales. Our model indicates that the cycle amplitude increases with reduction of krill loss rates. Thus, a decline of apex predators is likely to increase the oscillation amplitude, potentially destabilizing the marine food web, with drastic consequences for the entire Antarctic ecosystem.

Description: COST (Co-operation in the field of Scientific and Technical Research) is an important instrument supporting co-operation among scientists and researchers across Europe now joining 35 member countries. Scientific projects in the COST framework are called COST Actions and have the objectives embodied in their respective Memorandum of Understanding (MoU). The main objectives of the COST Actions within the European ionospheric and radio propagation community have been: to study the influence of upper atmospheric conditions on terrestrial and Earthspace communications, to develop methods and techniques to improve existing and generate new ionospheric and propagation models over Europe for telecommunication and navigation applications and to transfer the results to the appropriate national and international organizations, institutions and industry dealing with the modern communication systems. This paper summarises in brief the background and historical context of four ionospheric COST Actions and outlines their main objectives and results. In addition, the paper discusses the dissemination of the results and the collaboration among the participating institutions and researchers.

Description: DRS Codem Systems Ball Aerospace Corporation University of Massachusetts Lowell

Description: Published

Description: Lowell, Massachusetts, U.S.A., April 29, 2007

Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale

Description: open

Description: In the following we present a new non-invasive methodology aimed at the diagnosis of stone building materials used in historical buildings and architectural elements. This methodology consists of the integrated sequential application of in situ proximal sensing methodologies such as the 3D Terrestrial Laser Scanner for the 3D modelling of investigated objects together with laboratory and in situ non-invasive multi-techniques acoustic data, preceded by an accurate petrographical study of the investigated stone materials by optical and scanning electron microscopy. The increasing necessity to integrate different types of techniques in the safeguard of the Cultural Heritage is the result of the following two interdependent factors: 1) The diagnostic process on the building stone materials of monuments is increasingly focused on difficult targets in critical situations. In these cases, the diagnosis using only one type of non-invasive technique may not be sufficient to investigate the conservation status of the stone materials of the superficial and inner parts of the studied structures 2) Recent technological and scientific developments in the field of non-invasive diagnostic techniques for different types of materials favors and supports the acquisition, processing and interpretation of huge multidisciplinary datasets.

Description: Regione Autonoma della Sardegna (RAS) (Sardinian Autonomous Region), Regional Law 7th August 2007, no. 7, Promotion of scientific research and technological innovation in Sardinia (Italy).

Description: Published

Description: 4334

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: A high-resolution Fabry–Perot interferometer was inserted in a feedback loop which, by monitoring elements of the fringe pattern, keeps the position of the transmitting window fixed with respect to a given line, taking into account the instability of the radiation source which would produce a wander of the line itself and the noise affecting the tuning of the receiving interferometer. The system, in this preliminary form, is able to lock itself and maintain its position indefinitely for slow and moderately fast varying disturbances.

Description: Published

Description: 2940-2944

Description: 1.7. Osservazioni di alta e media atmosfera

Description: JCR Journal

Description: reserved

Description: For a comprehensive understanding of fish responses to increasing thermal stress in marine environments, we investigated tissue energetics, antioxidant levels, inflammatory and cell death responses in Sparus aurata (gilthead seabream) red muscle during exposure to elevated temperatures (24 °C, 26 °C, 30 °C) compared to the control temperature of 18 °C. Energetic aspects were assessed by determining lactate, glucose and lipids levels in blood plasma, ATP, ADP and AMP levels, and AMPK phosphorylation as an indicator of regulatory changes in energy metabolism, in tissue extracts. Oxidative defence was assessed by determining superoxide dismutase, catalase and glutathione reductase maximum activities. Moreover, xanthine levels were determined as an indicator of purine conversion to xanthine and associated ROS production. In the context of inflammatory response and cell death due to oxidative stress, pro-inflammatory cytokines (IkBα phosphorylation, IL-6 and TNFα) levels, and LC3 II/I ratio and SQSTM1/p62 as indicators of autophagic-lysosomal pathway were also determined. A recovery in the efficacy of ATP production after a marked decrease during the 1st day of exposure to 24 °C is observed. This biphasic pattern is paralleled by antioxidant enzymes’ activities and inflammatory and autophagy responses, indicating a close correlation between ATP turnover and stress responses, which may benefit tissue function and survival. However, exposure beyond 24 °C caused tissue’s antioxidant capacity loss, triggering the inflammatory and cell death response, lead-ing to increased fish mortality. The results of the present study set the thermal limits of the gilthead seabream at 22–24 °C and establish the used cellular and metabolic indicators as tools for the definition of the extreme thermal limits in marine organisms.

Description: The deglacial history of CO2 release from the deep North Pacific remains unresolved. This is due to conflicting indications about subarctic Pacific ventilation changes based on various marine proxies, especially for Heinrich Stadial 1 (HS-1) when a rapid atmospheric CO2 rise occurs. Here, we use a complex Earth System Model to investigate the deglacial North Pacific overturning and its control on ocean stratification. Our results show an enhanced intermediate-to-deep ocean stratification coeval with intensified North Pacific Intermediate Water (NPIW) formation during HS-1, compared to the Last Glacial Maximum. The stronger NPIW formation causes lower salinities and higher temperatures at intermediate depths. By lowering NPIW densities, this enlarges vertical density gradient and thus enhances intermediate-to-deep ocean stratification during HS-1. Physically, this process prevents the North Pacific deep waters from a better communication with the upper oceans, thus prolongs the existing isolation of glacial Pacific abyssal carbons during HS-1.

Description: An approach is presented for high-field MRI studies of the cardiovascular system (CVS) of a marine crustacean, the edible crab Cancer pagurus, submerged in highly conductive seawater. Structure and function of the CVS were investigated at 9.4 T. Cardiac motion was studied using self-gated CINE MRI. Imaging protocols and radio-frequency coil arrangements were tested for anatomical imaging. Haemolymph flow was quantified using phase-contrast angiography. Signal-to-noise-ratios and flow velocities in afferent and efferent branchial veins were compared with Student’s t test (n = 5). Seawater induced signal losses were dependent on imaging protocols and RF coil setup. Internal cardiac structures could be visualized with high spatial resolution within 8 min using a gradient-echo technique. Variations in haemolymph flow in different vessels could be determined over time. Maximum flow was similar within individual vessels and corresponded to literature values from Doppler measurements. Heart contractions were more pronounced in lateral and dorso-ventral directions than in the anterior–posterior direction. Choosing adequate imaging protocols in combination with a specific RF coil arrangement allows to monitor various parts of the crustacean CVS with exceptionally high spatial resolution despite the adverse effects of seawater at 9.4 T.

Description: At mid-ocean ridges volcanism generally decreases with spreading rate but surprisingly massive volcanic centres occur at the slowest spreading ridges. These volcanoes can host unexpectedly strong earthquakes and vigorous, explosive submarine eruptions. Our understanding of the geodynamic processes forming these volcanic centres is still incomplete due to a lack of geophysical data and the difficulty to capture their rare phases of magmatic activity. We present a local earthquake tomographic image of the magma plumbing system beneath the Segment 8 volcano at the ultraslow-spreading Southwest Indian Ridge. The tomography shows a confined domain of partial melt under the volcano. We infer that from there melt is horizontally transported to a neighbouring ridge segment at 35 km distance where microearthquake swarms and intrusion tremor occur that suggest ongoing magmatic activity. Teleseismic earthquakes around the Segment 8 volcano, prior to our study, indicate that the current magmatic spreading episode may already have lasted over a decade and hence its temporal extent greatly exceeds the frequent short-lived spreading episodes at faster opening mid-ocean ridges.

Description: Subglacial lakes are widespread beneath the Antarctic Ice Sheet but their control on ice-sheet dynamics and their ability to harbour life remain poorly characterized. Here we present evidence for a palaeo-subglacial lake on the Antarctic continental shelf. A distinct sediment facies recovered from a bedrock basin in Pine Island Bay indicates deposition within a low-energy lake environment. Diffusive-advection modelling demonstrates that low chloride concentrations in the pore water of the corresponding sediments can only be explained by initial deposition of this facies in a freshwater setting. These observations indicate that an active subglacial meltwater network, similar to that observed beneath the extant ice sheet, was also active during the last glacial period. It also provides a new framework for refining the exploration of these unique environments.

Description: Glaciological and oceanographic observations coupled with numerical models show that warm Circumpolar Deep Water (CDW) incursions onto the West Antarctic continental shelf cause melting of the undersides of floating ice shelves. Because these ice shelves buttress glaciers feeding into them, their ocean-induced thinning is driving Antarctic ice-sheet retreat today. Here we present a multi-proxy data based reconstruction of variability in CDW inflow to the Amundsen Sea sector, the most vulnerable part of the West Antarctic Ice Sheet, during the Holocene epoch (from 11.7 thousand years ago to the present). The chemical compositions of foraminifer shells and benthic foraminifer assemblages in marine sediments indicate that enhanced CDW upwelling, controlled by the latitudinal position of the Southern Hemisphere westerly winds, forced deglaciation of this sector from at least 10,400 years ago until 7,500 years ago—when an ice-shelf collapse may have caused rapid ice-sheet thinning further upstream—and since the 1940s. These results increase confidence in the predictive capability of current ice-sheet models.

Description: Sustainable Development Goal 14 of the United Nations aims to “conserve and sustainably use the oceans, seas and marine resources for sustainable development”. Achieving this goal will require rebuilding the marine life-support systems that deliver the many benefits that society receives from a healthy ocean. Here we document the recovery of marine populations, habitats and ecosystems following past conservation interventions. Recovery rates across studies suggest that substantial recovery of the abundance, structure and function of marine life could be achieved by 2050, if major pressures—including climate change—are mitigated. Rebuilding marine life represents a doable Grand Challenge for humanity, an ethical obligation and a smart economic objective to achieve a sustainable future.

Description: The intensification of Northern Hemisphere glaciations at the end of the Pliocene epoch marks one of the most substantial climatic shifts of the Cenozoic. Despite global cooling, sea surface temperatures in the high latitude North Atlantic Ocean rose between 2.9–2.7 million years ago. Here we present sedimentary geochemical proxy data from the Gulf of Cadiz to reconstruct the variability of Mediterranean Outflow Water, an important heat source to the North Atlantic. We find evidence for enhanced production of Mediterranean Outflow from the mid-Pliocene to the late Pliocene which we infer could have driven a sub-surface heat channel into the high-latitude North Atlantic. We then use Earth System Models to constrain the impact of enhanced Mediterranean Outflow production on the northward heat transport in the North Atlantic. In accord with the proxy data, the numerical model results support the formation of a sub-surface channel that pumped heat from the subtropics into the high latitude North Atlantic. We further suggest that this mechanism could have delayed ice sheet growth at the end of the Pliocene.

Description: In permafrost areas, seasonal freeze-thaw cycles of active layer result in upward and downward movements of the ground. Additionally, relatively uniform thawing of the ice-rich layer at the permafrost table, contributing to net long-term surface lowering, was reported for some Arctic locations. We use a simple method to quantify surface lowering (subsidence) and uplift in a yedoma area of the Lena River Delta, Siberian Arctic, using reference rods installed deeply in permafrost. The seasonal subsidence was 1.7 ±1.5 cm in the cold summer of 2013 and 4.8 ± 2 cm in the warm summer of 2014. Furthermore, we measured a pronounced multi-year net subsidence of 9.3 ± 5.7 cm from spring 2013 to the end of summer 2017. Additionally, we observed a high spatial variability of subsidence of up to 6 cm across a sub-meter horizontal scale. This variability limits the usage of a pointwise measurement for a validation of spatially extensive remote sensing products. In summer 2013, we accompanied our field measurements with Differential Synthetic Aperture Radar Interferometry (DInSAR) on repeat-pass TerraSAR-X (TSX) data over the same study area. Interferometry was strongly affected by a fast phase coherence loss, atmospheric artifacts, and possibly the choice of reference point. A cumulative ground displacement map, built from a continuous interferogram stack, did not reveal a meaningful signal on the upland but showed a distinct subsidence of up to 2 cm in most of the thermokarst basins. There, the spatial pattern of displacement corresponded well with relative surface wetness identified with the near infra-red band of a high-resolution optical image. Our study suggests that (i) although X-band SAR has serious limitations for ground movement monitoring in permafrost landscapes, it can provide valuable information for specific environments like thermokarst basins, and (ii) due to the high sub-pixel spatial variability of ground movements, a validation scheme needs to be developed and implemented for future DInSAR studies in permafrost environments.

Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ferrer-González, F. X., Widner, B., Holderman, N. R., Glushka, J., Edison, A. S., Kujawinski, E. B., & Moran, M. A. Resource partitioning of phytoplankton metabolites that support bacterial heterotrophy. ISME Journal, (2020), doi:10.1038/s41396-020-00811-y.

Description: The communities of bacteria that assemble around marine microphytoplankton are predictably dominated by Rhodobacterales, Flavobacteriales, and families within the Gammaproteobacteria. Yet whether this consistent ecological pattern reflects the result of resource-based niche partitioning or resource competition requires better knowledge of the metabolites linking microbial autotrophs and heterotrophs in the surface ocean. We characterized molecules targeted for uptake by three heterotrophic bacteria individually co-cultured with a marine diatom using two strategies that vetted the exometabolite pool for biological relevance by means of bacterial activity assays: expression of diagnostic genes and net drawdown of exometabolites, the latter detected with mass spectrometry and nuclear magnetic resonance using novel sample preparation approaches. Of the more than 36 organic molecules with evidence of bacterial uptake, 53% contained nitrogen (including nucleosides and amino acids), 11% were organic sulfur compounds (including dihydroxypropanesulfonate and dimethysulfoniopropionate), and 28% were components of polysaccharides (including chrysolaminarin, chitin, and alginate). Overlap in phytoplankton-derived metabolite use by bacteria in the absence of competition was low, and only guanosine, proline, and N-acetyl-d-glucosamine were predicted to be used by all three. Exometabolite uptake pattern points to a key role for ecological resource partitioning in the assembly marine bacterial communities transforming recent photosynthate.

Description: This work was supported by grants from the Gordon and Betty Moore Foundation (5503) and the National Science Foundation (IOS-1656311) to MAM, ASE, and EBK, and by the Simons Foundation grant 542391 to MAM within the Principles of Microbial Ecosystems (PriME) Collaborative.

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gruen, D. S., Wolfe, J. M., & Fournier, G. P.. Paleozoic diversification of terrestrial chitin-degrading bacterial lineages. BMC Evolutionary Biology, 19, (2019): 34, doi:10.1186/s12862-019-1357-8.

Description: Background Establishing the divergence times of groups of organisms is a major goal of evolutionary biology. This is especially challenging for microbial lineages due to the near-absence of preserved physical evidence (diagnostic body fossils or geochemical biomarkers). Horizontal gene transfer (HGT) can serve as a temporal scaffold between microbial groups and other fossil-calibrated clades, potentially improving these estimates. Specifically, HGT to or from organisms with fossil-calibrated age estimates can propagate these constraints to additional groups that lack fossils. While HGT is common between lineages, only a small subset of HGT events are potentially informative for dating microbial groups. Results Constrained by published fossil-calibrated studies of fungal evolution, molecular clock analyses show that multiple clades of Bacteria likely acquired chitinase homologs via HGT during the very late Neoproterozoic into the early Paleozoic. These results also show that, following these HGT events, recipient terrestrial bacterial clades likely diversified ~ 300–500 million years ago, consistent with established timescales of arthropod and plant terrestrialization. Conclusions We conclude that these age estimates are broadly consistent with the dispersal of chitinase genes throughout the microbial world in direct response to the evolution and ecological expansion of detrital-chitin producing groups. The convergence of multiple lines of evidence demonstrates the utility of HGT-based dating methods in microbial evolution. The pattern of inheritance of chitinase genes in multiple terrestrial bacterial lineages via HGT processes suggests that these genes, and possibly other genes encoding substrate-specific enzymes, can serve as a “standard candle” for dating microbial lineages across the Tree of Life.

Description: This work was supported by a National Science Foundation (NSF) Graduate Research Fellowship Program Award to DSG., and Simons Collaboration on the Origins of Life Award #339603 and NSF Integrated Earth Systems Program Award #1615426 to GPF. The funding agencies for this study had no role in study design, data collection, data analysis and interpretation, or in writing the manuscript.

Description: The effect of pressure on melt viscosity was investigated for five compositions along the join An(CaAl2Si2O8)–Di(CaMgSi2O6) and four alkali silicates containing lithium, sodium, and potassium in constant ratio of ∼ 1:1:1, but alkali-silica ratios are varying. The experiments were performed in an internally heated gas pressure vessel at pressures from 50 to 400 MPa in the viscosity range from 108 to 1011.5 Pa⋅s using parallel plate viscometry. The polymerized An composition shows a negative pressure dependence of viscosity while the other, more depolymerized compositions of the join An–Di have neutral to positive pressure coefficients. The alkali silicates display neutral to slightly positive pressure coefficients for melt viscosity. These findings in the high viscosity range of 108–1011 Pa⋅s, where pressure appears to be more efficient than in low viscous melts at high temperature, are consistent with previous results on the viscosity of polymerized to depolymerized melts in the system NaAlSi3O8–CaMgSi2O6 by Behrens and Schulze [ H. Behrens and F. Schulze, Am. Mineral. 88, 1351 (2003) ]. Thus we confirm that the sign of the pressure coefficient for viscosity is mainly related to the degree of melt polymerization in silicate and aluminosilicate melts.

Description: DFG Grant n.°BE1720/9

Description: Published

Description: 044504-14

Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce

Description: JCR Journal

Description: open

Description: Seismological findings show a complex scenario of plume upwellings from a deep thermo-chemical anomaly (superplume) beneath the East African Rift System (EARS). It is unclear if these geophysical observations represent a true picture of the superplume and its influence on magmatism along the EARS. Thus, it is essential to find a geochemical tracer to establish where upwellings are connected to the deep-seated thermo-chemical anomaly. Here we identify a unique non-volatile superplume isotopic signature (‘C’) in the youngest (after 10 Ma) phase of widespread EARS rift-related magmatism where it extends into the Indian Ocean and the Red Sea. This is the first sound evidence that the superplume influences the EARS far from the low seismic velocities in the magma-rich northern half. Our finding shows for the first time that superplume mantle exists beneath the rift the length of Africa from the Red Sea to the Indian Ocean offshore southern Mozambique

Description: This project started in October 2015 with a crazy idea: prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project.

Description: A set of four magnitude Ml≥3.0 earthquakes including the magnitude Ml=3.7 mainshock of the seismic sequence hitting the Lake Constance, Southern Germany, area in July–August 2019 was studied by means of bulletin and waveform data collected from 86 seismic stations of the Central Europe-Alpine region. The frst single-event locations obtained using a uniform 1-D velocity model, and both fxed and free depths, showed residuals of the order of up±2.0 s, systematically afecting stations located in diferent areas of the study region. Namely, German stations to the northeast of the epicenters and French stations to the west exhibit negative residuals, while Italian stations located to the southeast are characterized by similarly large positive residuals. As a consequence, the epicentral coordinates were afected by a signifcant bias of the order of 4–5 km to the NNE. The locations were repeated applying a method that uses diferent velocity models for three groups of stations situated in diferent geological environments, obtaining more accurate locations. Moreover, the application of two methods of relative locations and joint hypocentral determination, without improving the absolute location of the master event, has shown that the sources of the four considered events are separated by distances of the order of one km both in horizontal coordinates and in depths. A particular attention has been paid to the geographical positions of the seismic stations used in the locations and their relationship with the known crustal features, such as the Moho depth and velocity anomalies in the studied region. Signifcant correlations between the observed travel time residuals and the crustal structure were obtained.

Description: Published

Description: 1163–1175

Description: 1T. Struttura della Terra

Description: 2TR. Ricostruzione e modellazione della struttura crostale

Description: JCR Journal

Description: The Italian Apennines are among the most important sources of freshwater for several Italian regions. With evidences of deep CO2-rich fluids intruding into aquifers in the nearby central-southern Apennines, a thorough investigation into the geochemistry of groundwater became critical to ensure the water quality in the area. Here, we show the main hydrogeochemical processes occurring in the Matese Massif (MM) aquifer through the investigation of 98 water samples collected from springs and water wells. All waters were classified as HCO3 type with Ca dominance (from 50% up to 97%) and variable amount of Mg (from 1% up to 49%). A multivariate statistical approach through the application of the factor analysis (FA) highlighted three main hydrogeochemical processes: (i) water-carbonate rock interactions mostly enhanced in peripheral areas of the MM by CO2 deep degassing; (ii) addition of NaCl-rich components linked to recharging process and to water mixing processes of the groundwater with a thermal component relatively rich in Cl, Na, and CO2; (iii) anthropogenic activities influencing groundwater composition at the foothills of MM. Furthermore, the first detailed TDIC, pCO2, and δ13C-TDIC distribution maps of the MM area have been created, which track chemical and isotopic anomalies in several peripheral areas (Pratella, Ailano, and Telese) throughout the region. These maps systematically highlight that the greater the amount of dissolved carbon occurs the heavier the C isotope enrichment, especially in the peripheral areas. Conversely, spring waters emerging at higher altitudes within MM are only slightly mineralized and associated with δ13C-TDIC values mainly characterized by recharging processes with the addition of biogenic carbon during the infiltration process through the soil.

Description: Published

Description: 46614–46626

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: 2IT. Laboratori analitici e sperimentali

Description: JCR Journal

Description: Geothermal heat flow in the polar regions plays a crucial role in understanding ice-sheet dynamics and predictions of sea level rise. Continental-scale indirect estimates often have a low spatial resolution and yield largest discrepancies in West Antarctica. Here we analyse geophysical data to estimate geothermal heat flow in the Amundsen Sea Sector of West Antarctica. With Curie depth analysis based on a new magnetic anomaly grid compilation, we reveal variations in lithospheric thermal gradients. We show that the rapidly retreating Thwaites and Pope glaciers in particular are underlain by areas of largely elevated geothermal heat flow, which relates to the tectonic and magmatic history of the West Antarctic Rift System in this region. Our results imply that the behavior of this vulnerable sector of the West Antarctic Ice Sheet is strongly coupled to the dynamics of the underlying lithosphere.

Description: Of all the socio-economic changes caused by the Covid-19 pandemic, the disruption to workforce organizations will probably leave the largest indelible mark. The way work will be organized in the future will be closely linked to the experience of work-ing under the same institution’s response to the pandemic. This paper aims to fill the gap in knowledge about smart working (SW) in public organizations, with a focus on the experience of the employees of two Italian research organizations, CNR and INGV. Analysing primary data, it explored and assessed how SW had been experi-enced following the implementation of governmental measures aimed at limiting the spread of COVID-19

Description: Published

Description: 815–833

Description: 2TM. Divulgazione Scientifica

Description: JCR Journal

Description: Data visualization, and to a lesser extent data sonification, are classic tools to the scientific community. However, these two approaches are very rarely combined, although they are highly complementary: our visual system is good at recognizing spatial patterns, whereas our auditory system is better tuned for temporal patterns. In this article, data representation methods are proposed that combine visualization, sonification, and spatial audio techniques, in order to optimize the user’s perception of spatial and temporal patterns in a single display, to increase the feeling of immersion, and to take advantage of multimodal integration mechanisms. Three seismic data sets are used to illustrate the methods, covering different physical phenomena, time scales, spatial distributions, and spatio-temporal dynamics. The methods are adapted to the specificities of each data set, and to the amount of information that the designer wants to display. This leads to further developments, namely the use of audification with two time scales, the switch from pure audification to time-modulated noise, and the switch from pure audification to sonic icons. First user feedback from live demonstrations indicates that the methods presented in this article seem to enhance the perception of spatio-temporal patterns, which is a key parameter to the understanding of seismically active systems, and a step towards apprehending the processes that drive this activity.

Description: Published

Description: 125–142

Description: 7T. Variazioni delle caratteristiche crostali e "precursori"

Description: JCR Journal

Description: Lagoon development in ice-rich permafrost environments such as the Alaskan Beaufort Sea coastline and the Yedoma coastlines of northern Siberia represents a key mechanism of marine inundation of permafrost along the Arctic coastal plains. Here we show lithological, geochronological, and geochemical data from a core drilled in 1999 in Ivashkina Lagoon on the Bykovsky Peninsula in northeastern Siberia. This study extends previous studies of the Ivashkina Lagoon, and provides a first dated geochronological context for sedimentation and lithological characteristics. In addition, we report ground temperature measurements from different borehole sites in and around the lagoon to support our analysis of the thermokarst lagoon environment. Furthermore, a change detection study was carried out using historical aerial photography and modern satellite imagery for the 1982 to 2016 period. Several stages of landscape dynamics were reconstructed, starting with an initial Yedoma Ice Complex that covered the area during the late Pleistocene and which was locally thawed by thermokarst lake development during the Late Glacial with subsequent lacustrine sedimentation. A final stage completed the landscape dynamics during the last few hundreds of years. This stage was characterized by lake drainage and lagoon development, including strong reworking of surface sediments. By extrapolating the organic carbon data from Ivashkina Lagoon to the lagoons of the Bykovsky Peninsula, we estimate that lagoons contain 1.68 ± 0.04 Mt of organic carbon in their upper 6 m.

Description: The stability of the West Antarctic Ice Sheet is threatened by the incursion of warm Circumpolar Deepwater which flows southwards via cross-shelf troughs towards the coast there melting ice shelves. However, the onset of this oceanic forcing on the development and evolution of the West Antarctic Ice Sheet remains poorly understood. Here, we use single- and multichannel seismic reflection profiles to investigate the architecture of a sediment body on the shelf of the Amundsen Sea Embayment. We estimate the formation age of this sediment body to be around the Eocene-Oligocene Transition and find that it possesses the geometry and depositional pattern of a plastered sediment drift. We suggest this indicates a southward inflow of deep water which probably supplied heat and, thus, prevented West Antarctic Ice Sheet advance beyond the coast at this time. We conclude that the West Antarctic Ice Sheet has likely experienced a strong oceanic influence on its dynamics since its initial formation.

Description: Succession of cold glacials and warm interglacials during the Quaternary results from large global climate responses to variable orbital configurations, accompanied by fluctuating greenhouse gas concentrations. Despite the influences of sea ice and atmospheric and ocean circulations in the Southern Ocean on atmospheric CO2 concentrations and climate, past changes in this region remain poorly documented. Here, we present the 800 ka deuterium excess record from the East Antarctica EPICA Dome C ice core, tracking sea surface temperature in evaporative regions of the Indian sector of the Southern Ocean from which moisture precipitated in East Antarctica is derived. We find that low obliquity leads to surface warming in evaporative moisture source regions during each glacial inception, although this relative temperature increase is counterbalanced by global cooling during glacial maxima. Links between the two regions during interglacials depends on the existence of a temperature maximum at the interglacial onset. In its absence, temperature maxima in the evaporative moisture source regions and in East Antarctica were synchronous. For the other interglacials, temperature maxima in the source areas lag early local temperature maxima by several thousand years, probably because of a change in the position of the evaporative source areas.

Description: Over the past decades, two key grazers in the Southern Ocean (SO), krill and salps, have experienced drastic changes in their distribution and abundance, leading to increasing overlap of their habitats. Both species occupy different ecological niches and long-term shifts in their distributions are expected to have cascading effects on the SO ecosystem. However, studies directly comparing krill and salps are lacking. Here, we provide a direct comparison of the diet and fecal pellet composition of krill and salps using 18S metabarcoding and fatty acid markers. Neither species’ diet reflected the composition of the plankton community, suggesting that in contrast to the accepted paradigm, not only krill but also salps are selective feeders. Moreover, we found that krill and salps had broadly similar diets, potentially enhancing the competition between both species. This could be augmented by salps’ ability to rapidly reproduce in favorable conditions, posing further risks to krill populations.

Description: Short-term earthquake clustering properties in the Eastern Aegean Sea (Greece) area investigated through the application of an epidemic type stochastic model (Epidemic Type Earthquake Sequence; ETES). The computations are performed in an earthquake catalog covering the period 2008 to 2020 and including 2332 events with a completeness threshold of Mc = 3.1 and separated into two subcatalogs. The first subcatalog is employed for the learning period, which is between 2008/01/01 and 2016/12/31 (N = 1197 earthquakes), and used for the model’s parameters estimation. The second subcatalog from 2017/01/01 to 2020/11/10 (1135 earthquakes), in which the sequences of 2017 Mw = 6.4 Lesvos, 2017 Mw = 6.6 Kos and 2020 Mw = 7.0 Samos main shocks are included, and used for a retrospective forecast testing based on the constructed model. The estimated model parameters imply a swarm like behavior, indicating the ability of earthquakes of small to moderate magnitude above Mc to produce their own offsprings, along with the stronger earthquakes. The retrospective evaluation of the model is examined in the three aftershock sequences, where lack of foreshocks resulted in low predictability of the mainshocks, with estimated daily probabilities around 10– 5. Immediately after the mainshocks occurrence the model adjusts with notable resemblance between the expected and observed aftershock rates, particularly for earthquakes with M ≥ 3.5.

Description: Published

Description: 1085–1099

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: This work presents an up-to-date model for the simulation of non-stationary ground motions, including several novelties compared to the original study of Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996). The selection of the input motion in the framework of earthquake engineering has become progressively more important with the growing use of nonlinear dynamic analyses. Regardless of the increasing availability of large strong motion databases, ground motion records are not always available for a given earthquake scenario and site condition, requiring the adoption of simulated time series. Among the different techniques for the generation of ground motion records, we focused on the methods based on stochastic simulations, considering the time- frequency decomposition of the seismic ground motion. We updated the non-stationary stochastic model initially developed in Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996) and later modified by Pousse et al. (Bull Seism Soc Am 96:2103–2117, 2006) and Laurendeau et al. (Nonstationary stochastic simulation of strong ground-motion time histories: application to the Japanese database. 15 WCEE Lisbon, 2012). The model is based on the S-transform that implicitly considers both the amplitude and frequency modulation. The four model parameters required for the simulation are: Arias intensity, significant duration, central frequency, and frequency bandwidth. They were obtained from an empirical ground motion model calibrated using the accelerometric records included in the updated Italian strong-motion database ITACA. The simulated accelerograms show a good match with the ground motion model prediction of several amplitude and frequency measures, such as Arias intensity, peak acceleration, peak velocity, Fourier spectra, and response spectra.

Description: Published

Description: 3287–3315

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: Probabilistic earthquake locations provide confidence intervals for the hypocentre solutions such as errors encountered in the position, the origin time, and in magnitude. If the relationship of the parameters relative to the local arrangement of the seismic network is considered, such as the node distance, the number of stations, the seismic gap, and the quality of phase readings), the uncertainties can then provide insights on the location capability of the network. In this paper, we collect the earthquake data recorded from the Italian Seismic Network for a time span of 5 years. The data pertain to three different catalogues according to the progressive refinement phases of the location procedure: automatic location, revised location, and published location. By means of spatial analysis,we assess the distribution of the location-related and network-related estimators across the study area. These estimators are subsequently combined to assess the existence of spatial correlations at a local scale. The results indicate that the Italian network is generally able to provide robust locations at the national scale and for smaller earthquakes, and the elongated shape of Italy (and of its network) does not cause systematic bias in the locations. However, we highlight the existence of subregions in which the performance of the network is weaker. At present, a unique 2D, 3-layer velocity model is used for the earthquake location procedure, and this could represent the main limitation for the improvement of the locations. Therefore, the assessment of locally optimized velocity models is the priority for the homogenization and the improvement of the Italian Seismic Network performance.

Description: Published

Description: 1061–1076

Description: 1IT. Reti di monitoraggio e sorveglianza

Description: JCR Journal

Description: This paper provides a new contribution to the construction of the complex and fragmentary mosaic of the Late Holocene earthquakes history of the İznik segment of the central strand of the North Anatolian Fault (CNAF) in Turkey. The CNAF clearly displays lower dextral slip rates with respect to the northern strand however, surface rupturing and large damaging earthquakes (M 〉 7) occurred in the past, leaving clear signatures in the built and natural environments. The association of these historical events to specific earthquake sources (e.g., Gemlik, İznik, or Geyve fault segments) is still a matter of debate. We excavated two trenches across the İznik fault trace near Mustafali, a village about 10 km WSW of İznik where the morphological fault scarp was visible although modified by agricultural activities. Radiocarbon and TL dating on samples collected from the trenches show that the displaced deposits are very recent and span the past 2 millennia at most. Evidence for four surface faulting events was found in the Mustafali trenches. The integration of these results with historical data and previous paleoseismological data yields an updated Late Holocene history of surface-rupturing earthquakes along the İznik Fault in 1855, 740 (715), 362, and 121 CE. Evidence for the large M7 + historical earthquake dated 1419 CE generally attributed to this fault, was not found at any trench site along the İznik fault nor in the subaqueous record. This unfit between paleoseismological, stratigraphic, and historical data highlights one more time the urge for extensive paleoseismological trenching and offshore campaigns because of the high potential to solve the uncertainties on the seismogenic history (age, earthquake location, extent of the rupture and size) of this portion of NAFZ and especially on the attribution of historical earthquakes to the causative fault.

Description: Published

Description: 115–128

Description: 2T. Deformazione crostale attiva

Description: N/A or not JCR

Description: In this paper the site categorization criteria and the corresponding site amplification factors proposed in the 2021 draft of Part 1 of Eurocode 8 (2021-draft, CEN/TC250/SC8 Working Draft N1017) are first introduced and compared with the current version of Eurocode 8, as well as with site amplification factors from recent empirical ground motion prediction equations. Afterwards, these values are checked by two approaches. First, a wide dataset of strong motion records is built, where recording stations are classified according to 2021-draft, and the spectral amplifications are empirically estimated computing the site-to-site residuals from regional and global ground motion models for reference rock conditions. Second, a comprehensive parametric numerical study of one-dimensional (1D) site amplification is carried out, based on randomly generated shear-wave velocity profiles, classified according to the new criteria. A reasonably good agreement is found by both approaches. The most relevant discrepancies occur for the shallow soft soil conditions (soil category E) that, owing to the complex interaction of shear wave velocity, soil deposit thickness and frequency range of the excitation, show the largest scatter both in terms of records and of 1D numerical simulations. Furthermore, 1D numerical simulations for soft soil conditions tend to provide lower site amplification factors than 2021-draft, as well as lower than the corresponding site-to-site residuals from records, because of higher impact of non-linear (NL) site effects in the simulations. A site-specific study on NL effects at three KiK-net stations with a significantly large amount of high-intensity recorded ground motions gives support to the 2021-draft NL reduction factors, although the very limited number of recording stations allowing such analysis prevents deriving more general implications. In the presence of such controversial arguments, it is reasonable that a standard should adopt a prudent solution, with a limited reduction of the site amplification factors to account for NL soil response, while leaving the possibility to carry out site-specific estimations of such factors when sufficient information is available to model the ground strain dependency of local soil properties.

Description: Published

Description: 4199–4234

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: ShakeMap is the tool to evaluate the ground motion effect of earthquakes in vast areas. It is useful to delimit the zones where the shaking is expected to have been most significant, for civil defense rapid response. From the earthquake engineering point of view, it can be used to infer the seismic actions on the built environment to calibrate vulnerability models or to define the reconstruction policies based on observed damage vs shaking. In the case of long-lasting seismic sequences, it can be useful to develop ShakeMap envelopes, that is, maps of the largest ground intensity among those from the ShakeMap of (selected) events of a seismic sequence, to delimit areas where the effects of the whole sequence have been of structural engineering relevance. This study introduces ShakeMap envelopes and discusses them for the central Italy 2016–2017 seismic sequence. The specific goals of the study are: (i) to compare the envelopes and the ShakeMap of the main events of the sequence to make the case for sequence-based maps; (ii) to quantify the exceedance of design seismic actions based on the envelopes; (iii) to make envelopes available for further studies and the reconstruction planning; (iv) to gather insights on the (repeated) exceedance of design seismic actions at some sites. Results, which include considerations of uncertainty in ShakeMap, show that the sequence caused exceedance of design hazard in thousands of square kilometers. The most relevant effects of the sequence are, as expected, due to the mainshock, yet seismic actions larger than those enforced by the code for structural design are found also around the epicenters of the smaller magnitude events. At some locations, the succession of ground-shaking that has excited structures, provides insights on structural damage accumulation that has likely taken place; something that is not accounted for explicitly in modern seismic design. The envelopes developed are available as supplemental material.

Description: Published

Description: 5391–5414

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: Analyzing seismic data to get information about earthquakes has always been a major task for seismologists and, more in general, for geophysicists. Recently, thanks to the technological development of observation systems, more and more data are available to perform such tasks. However, this data “grow up” makes “human possibility” of data processing more complex in terms of required efforts and time demanding. That is why new technological approaches such as artificial intelligence are becoming very popular and more and more exploited. In this paper, we explore the possibility of interpreting seismic waveform segments by means of pre-trained deep learning. More specifically, we apply convolutional networks to seismological waveforms recorded at local or regional distances without any pre-elaboration or filtering. We show that such an approach can be very successful in determining if an earthquake is “included” in the seismic wave image and in estimating the distance between the earthquake epicenter and the recording station.

Description: Published

Description: 1347–1359

Description: 1T. Struttura della Terra

Description: 3T. Fisica dei terremoti e Sorgente Sismica

Description: JCR Journal

Description: Themain climatological features of the ionospheric equivalent slab thickness (τ ) for the Northern hemispheremidlatitudes are analyzed. F2-layer peak electron density values recorded at three midlatitude ionospheric stations (Chilton 51.5° N, 0.6° W, U.K.; Roquetes 40.8° N, 0.5° E, Spain;Wallops Island 37.9° N, 75.5°W, USA) and vertical total electron content values from colocated ground-based Global Navigation Satellite System receivers are used to calculate a dataset of τ values for the last two solar cycles, considering only magnetically quiet periods. Results are presented both as grids of binned medians and as boxplots as a function of local time and month of the year, for different solar activity levels. Corresponding trends are first compared to those output by the midlatitude empirical model developed by Fox et al. (Radio Sci 26:429–438, 1991) and then discussed in the light of what is known so far. From this investigation, the strong need to implement an improved empirical model of τ has emerged. Both Space Weather and Space Geodesy applications might benefit from such model. Therefore, both the dataset and the methodology described in the paper represent a first fundamental step aimed at implementing an empirical climatological model of the ionospheric equivalent slab thickness. The study highlighted also that at midlatitudes τ shows the following main patterns: daytime values considerably smaller than nighttime ones (except in summer); well-defined maxima at solar terminator hours; a greater dispersion during nighttime and solar terminator hours; no clear and evident solar activity dependence.

Description: Published

Description: 124

Description: 2A. Fisica dell'alta atmosfera

Description: JCR Journal

Description: The eruption of basaltic magmas dominates explosive volcanism on Earth and other planets within the Solar System. The mechanism through which continuous magma fragments into volcanic particles is central in governing eruption dynamics and the ensuing hazards. However, the mechanism of fragmentation of basaltic magmas is still disputed, with both viscous and brittle mechanisms having been proposed. Here we carry out textural analysis of the products of ten eruptions from seven volcanoes by scanning electron microscopy. We find broken crystals surrounded by intact glass that testify to the brittle fragmentation of basaltic magmas during explosive activity worldwide. We then replicated the natural textures of broken crystals in laboratory experiments where variably crystallized basaltic melt was fragmented by rapid deformation. The experiments reveal that crystals are broken by the propagation of a network of fractures through magma, and that afterwards the fractures heal by viscous flow of the melt. Fracturing and healing affect gas mobility, stress distribution, and bubble and crystal size distributions in magma. Our results challenge the idea that the grain size distribution of basaltic eruption products reflects the density of fractures that initially fragmented the magma and ultimately indicate that brittle fracturing and viscous healing of magma may underlie basaltic explosive eruptions globally.

Description: Published

Description: 248–254

Description: 4V. Processi pre-eruttivi

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: Magmatism accompanies rifting along divergent plate boundaries, although its role before continental breakup remains poorly understood. For example, the magma-assisted Northern Main Ethiopian Rift (NMER) lacks current volcanism and clear tectono-magmatic relationships with its contiguous rift portions. Here we define its magmatic behaviour, identifying the most recent eruptive fissures (EF) whose aphyric basalts have a higher Ti content than those of older monogenetic scoria cones (MSC), which are porphyritic and plagioclase-dominated. Despite these differences, calculations highlight a similar parental melt for EF and MSC products, suggesting only a different evolutionary history after melt generation. While MSC magmas underwent a further step of storage at intermediate crustal levels, EF magmas rose directly from the base of the crust without contamination, even below older polygenetic volcanoes, suggesting rapid propagation of transcrustal dikes across solidified magma chambers. Whether this recent condition in the NMER is stable or transient, it indicates a transition from central polygenetic to linear fissure volcanism, indicative of increased tensile conditions and volcanism directly fed from the base of the crust, suggesting transition towards mature rifting.

Description: Published

Description: 21821

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: This book serves as a guide to discovering the most interesting volcano sites in Italy. Accompanied by some extraordinary contemporary images of active Neapolitan volcanoes, it explains the main volcanic processes that have been shaping the landscape of the Campania region and influencing human settlements in this area since Greek and Roman times and that have prompted leading international scientists to visit and study this natural volcanology laboratory. While volcanology is the central topic, the book also addresses other aspects related to the area’s volcanism and is divided into three sections: 1) Neapolitan volcanic activity and processes (with a general introduction to volcanology and its development around Naples together with descriptions of the landscape and the main sites worth visiting); 2) Volcanoes and their interactions with local human settlements since the Bronze Age, recent population growth and the transformation of the territory; 3) The risks posed by Neapolitan Volcanoes, their recent activity and the problem of forecasting any future eruption.

Description: Published

Description: 2TM. Divulgazione Scientifica

Description: The stratified Chilean Comau Fjord sustains a dense population of the cold-water coral (CWC) Desmophyllum dianthus in aragonite supersaturated shallow and aragonite under- saturated deep water. This provides a rare opportunity to evaluate CWC fitness trade-offs in response to physico-chemical drivers and their variability. Here, we combined year-long reciprocal transplantation experiments along natural oceanographic gradients with an in situ assessment of CWC fitness. Following transplantation, corals acclimated fast to the novel environment with no discernible difference between native and novel (i.e. cross-transplanted) corals, demonstrating high phenotypic plasticity. Surprisingly, corals exposed to lowest ara- gonite saturation (Ωarag 〈 1) and temperature (T 〈 12.0 °C), but stable environmental condi- tions, at the deep station grew fastest and expressed the fittest phenotype. We found an inverse relationship between CWC fitness and environmental variability and propose to consider the high frequency fluctuations of abiotic and biotic factors to better predict the future of CWCs in a changing ocean.

Description: The El Niño/Southern Oscillation (ENSO), the dominant driver of year-to-year climate variability in the equatorial Pacific Ocean, impacts climate pattern across the globe. However, the response of the ENSO system to past and potential future temperature increases is not fully understood. Here we investigate ENSO variability in the warmer climate of the mid-Pliocene (~3.0–3.3 Ma), when surface temperatures were ~2–3 °C above modern values, in a large ensemble of climate models—the Pliocene Model Intercomparison Project. We show that the ensemble consistently suggests a weakening of ENSO variability, with a mean reduction of 25% (±16%). We further show that shifts in the equatorial Pacific mean state cannot fully explain these changes. Instead, ENSO was suppressed by a series of off-equatorial processes triggered by a northward displacement of the Pacific intertropical convergence zone: weakened convective feedback and intensified Southern Hemisphere circulation, which inhibit various processes that initiate ENSO. The connection between the climatological intertropical convergence zone position and ENSO we find in the past is expected to operate in our warming world with important ramifications for ENSO variability.

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zakem, E. J., Mahadevan, A., Lauderdale, J. M., & Follows, M. J. Stable aerobic and anaerobic coexistence in anoxic marine zones. ISME Journal, 14, (2019): 288–301, doi: 10.1038/s41396-019-0523-8.

Description: Mechanistic description of the transition from aerobic to anaerobic metabolism is necessary for diagnostic and predictive modeling of fixed nitrogen loss in anoxic marine zones (AMZs). In a metabolic model where diverse oxygen- and nitrogen-cycling microbial metabolisms are described by underlying redox chemical reactions, we predict a transition from strictly aerobic to predominantly anaerobic regimes as the outcome of ecological interactions along an oxygen gradient, obviating the need for prescribed critical oxygen concentrations. Competing aerobic and anaerobic metabolisms can coexist in anoxic conditions whether these metabolisms represent obligate or facultative populations. In the coexistence regime, relative rates of aerobic and anaerobic activity are determined by the ratio of oxygen to electron donor supply. The model simulates key characteristics of AMZs, such as the accumulation of nitrite and the sustainability of anammox at higher oxygen concentrations than denitrification, and articulates how microbial biomass concentrations relate to associated water column transformation rates as a function of redox stoichiometry and energetics. Incorporating the metabolic model into an idealized two-dimensional ocean circulation results in a simulated AMZ, in which a secondary chlorophyll maximum emerges from oxygen-limited grazing, and where vertical mixing and dispersal in the oxycline also contribute to metabolic co-occurrence. The modeling approach is mechanistic yet computationally economical and suitable for global change applications.

Description: We are grateful for the thorough and thoughtful comments of two anonymous reviewers. We also thank Andrew Babbin for helpful comments. EJZ was supported by the Simons Foundation (Postdoctoral Fellowship in Marine Microbial Ecology). AM was supported by the Office of Naval Research (ONR #N000-14-15-1-2555). JML was supported by U.S. National Science Foundation (NSF #OCE-1259388). MJF was supported by the Gordon and Betty Moore Foundation (GBMF #3778) and the Simons Foundation: the Simons Collaboration on Ocean Processes and Ecology (SCOPE #329108) and the Simons Collaboration on Computational Biogeochemical Modeling of Marine Ecosystems (CBIOMES #549931).

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ponnudurai, R., Heiden, S. E., Sayavedra, L., Hinzke, T., Kleiner, M., Hentschker, C., Felbeck, H., Sievert, S. M., Schlüter, R., Becher, D., Schweder, T., & Markert, S. Comparative proteomics of related symbiotic mussel species reveals high variability of host-symbiont interactions. ISME Journal, 14, (2019): 649–656, doi: 10.1038/s41396-019-0517-6.

Description: Deep-sea Bathymodiolus mussels and their chemoautotrophic symbionts are well-studied representatives of mutualistic host–microbe associations. However, how host–symbiont interactions vary on the molecular level between related host and symbiont species remains unclear. Therefore, we compared the host and symbiont metaproteomes of Pacific B. thermophilus, hosting a thiotrophic symbiont, and Atlantic B. azoricus, containing two symbionts, a thiotroph and a methanotroph. We identified common strategies of metabolic support between hosts and symbionts, such as the oxidation of sulfide by the host, which provides a thiosulfate reservoir for the thiotrophic symbionts, and a cycling mechanism that could supply the host with symbiont-derived amino acids. However, expression levels of these processes differed substantially between both symbioses. Backed up by genomic comparisons, our results furthermore revealed an exceptionally large repertoire of attachment-related proteins in the B. thermophilus symbiont. These findings imply that host–microbe interactions can be quite variable, even between closely related systems.

Description: Thanks to captain, crew, and pilots of the research vessels Atlantis (ROV Jason cruise AT26–10 in 2014) and Meteor (cruise M82–3 in 2010). We thank Jana Matulla, Sebastian Grund, and Annette Meuche for excellent technical assistance during sample preparation, MS measurements in the Orbitrap Classic, and TEM imaging preparation, respectively. We appreciate Nikolaus Leisch’s help with TEM image interpretation, Inna Sokolova’s advice on bivalve physiology, and Marie Zühlke’s support during manuscript revision. RP was supported by the EU-funded Marie Curie Initial Training Network ‘Symbiomics’ (project no. 264774) and by a fellowship of the Institute of Marine Biotechnology e.V. TH was supported by the German Research Foundation DFG (grant MA 6346/2–1 to SM). The Atlantis cruise was funded by a grant of the US National Science Foundation’s Dimensions of Biodiversity program to SMS (OCE-1136727).

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Miller, C. A., Holm, H. C., Horstmann, L., George, J. C., Fredricks, H. F., Van Mooy, B. A. S., & Apprill, A. Coordinated transformation of the gut microbiome and lipidome of bowhead whales provides novel insights into digestion. ISME Journal, 14, (2019): 688-701, doi: 10.1038/s41396-019-0549-y.

Description: Whale digestion plays an integral role in many ocean ecosystems. By digesting enormous quantities of lipid-rich prey, whales support their energy intensive lifestyle, but also excrete nutrients important to ocean biogeochemical cycles. Nevertheless, whale digestion is poorly understood. Gastrointestinal microorganisms play a significant role in vertebrate digestion, but few studies have examined them in whales. To investigate digestion of lipids, and the potential contribution of microbes to lipid digestion in whales, we characterized lipid composition (lipidomes) and bacterial communities (microbiotas) in 126 digesta samples collected throughout the gastrointestinal tracts of 38 bowhead whales (Balaena mysticetus) harvested by Alaskan Eskimos. Lipidomes and microbiotas were strongly correlated throughout the gastrointestinal tract. Lipidomes and microbiotas were most variable in the small intestine and most similar in the large intestine, where microbiota richness was greatest. Our results suggest digestion of wax esters, the primary lipids in B. mysticetus prey representing more than 80% of total dietary lipids, occurred in the mid- to distal small intestine and was correlated with specific microorganisms. Because wax esters are difficult to digest by other marine vertebrates and constitute a large reservoir of carbon in the ocean, our results further elucidate the essential roles that whales and their gastrointestinal microbiotas play in the biogeochemical cycling of carbon and nutrients in high-latitude seas.

Description: Devonshire Foundation (to CAM), Marine Mammal Center, Woods Hole Oceanographic Institution (WHOI; to CAM), WHOI Ocean Life Institute (to AA and CAM), Dalio Foundation’s Dalio Ocean Initiative (now ‘OceanX’) (to AA), National Science Foundation (OCE-1756254 and OPP-1543328 to BASVM). Samples were collected under Department of Commerce National Oceanic and Atmospheric Administration National Marine Fisheries Service permit numbers 17350-00, 17350-01, and 17350-02 to North Slope Borough Department of Wildlife Management.

Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gazitua, M. C., Vik, D. R., Roux, S., Gregory, A. C., Bolduc, B., Widner, B., Mulholland, M. R., Hallam, S. J., Ulloa, O., & Sullivan, M. B. Potential virus-mediated nitrogen cycling in oxygen-depleted oceanic waters. Isme Journal, (2020), doi:10.1038/s41396-020-00825-6.

Description: Viruses play an important role in the ecology and biogeochemistry of marine ecosystems. Beyond mortality and gene transfer, viruses can reprogram microbial metabolism during infection by expressing auxiliary metabolic genes (AMGs) involved in photosynthesis, central carbon metabolism, and nutrient cycling. While previous studies have focused on AMG diversity in the sunlit and dark ocean, less is known about the role of viruses in shaping metabolic networks along redox gradients associated with marine oxygen minimum zones (OMZs). Here, we analyzed relatively quantitative viral metagenomic datasets that profiled the oxygen gradient across Eastern Tropical South Pacific (ETSP) OMZ waters, assessing whether OMZ viruses might impact nitrogen (N) cycling via AMGs. Identified viral genomes encoded six N-cycle AMGs associated with denitrification, nitrification, assimilatory nitrate reduction, and nitrite transport. The majority of these AMGs (80%) were identified in T4-like Myoviridae phages, predicted to infect Cyanobacteria and Proteobacteria, or in unclassified archaeal viruses predicted to infect Thaumarchaeota. Four AMGs were exclusive to anoxic waters and had distributions that paralleled homologous microbial genes. Together, these findings suggest viruses modulate N-cycling processes within the ETSP OMZ and may contribute to nitrogen loss throughout the global oceans thus providing a baseline for their inclusion in the ecosystem and geochemical models.

Description: We thank Sullivan Lab members and Heather Maughan for comments on the paper, Bess Ward for her contribution in the N-cycle context of our story, Kurt Hanselmann for his assistance in the calculations of the Gibbs-free energies, and the scientific party and crew of the R/V Atlantis (grant OCE-1356056 to MRM) for the sampling opportunity and support at sea. This work was funded in part by awards from the Agouron Institute to OU and MBS, a Gordon and Betty Moore Foundation Investigator Award (#3790) and NSF Biological Oceanography Awards (#1536989 and #1829831) to MBS, and the Millennium Science Initiative (grant ICN12_019-IMO) to OU. The work conducted by the U.S. Department of Energy Joint Genome Institute is supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC02-05CH11231.

Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Babbin, A. R., Tamasi, T., Dumit, D., Weber, L., Rodríguez, M. V. I., Schwartz, S. L., Armenteros, M., Wankel, S. D., & Apprill, A. Discovery and quantification of anaerobic nitrogen metabolisms among oxygenated tropical Cuban stony corals. ISME Journal, (2020), doi:10.1038/s41396-020-00845-2.

Description: Coral reef health depends on an intricate relationship among the coral animal, photosynthetic algae, and a complex microbial community. The holobiont can impact the nutrient balance of their hosts amid an otherwise oligotrophic environment, including by cycling physiologically important nitrogen compounds. Here we use 15N-tracer experiments to produce the first simultaneous measurements of ammonium oxidation, nitrate reduction, and nitrous oxide (N2O) production among five iconic species of reef-building corals (Acropora palmata, Diploria labyrinthiformis, Orbicella faveolata, Porites astreoides, and Porites porites) in the highly protected Jardines de la Reina reefs of Cuba. Nitrate reduction is present in most species, but ammonium oxidation is low potentially due to photoinhibition and assimilatory competition. Coral-associated rates of N2O production indicate a widespread potential for denitrification, especially among D. labyrinthiformis, at rates of ~1 nmol cm−2 d−1. In contrast, A. palmata displays minimal active nitrogen metabolism. Enhanced rates of nitrate reduction and N2O production are observed coincident with dark net respiration periods. Genomes of bacterial cultures isolated from multiple coral species confirm that microorganisms with the ability to respire nitrate anaerobically to either dinitrogen gas or ammonium exist within the holobiont. This confirmation of anaerobic nitrogen metabolisms by coral-associated microorganisms sheds new light on coral and reef productivity.

Description: Research was conducted in the Gardens of the Queen, Cuba in accordance with the requirements of the Republic of Cuba, conducted under permit NV2370 and NV2568 issued by the Ministerio de Relaciones Exteriores. We gratefully acknowledge funding for this research by MIT Sea Grant award #2018-DOH-49-LEV, Simons Foundation award #622065, and MIT ESI seed funding to ARB, the MIT Montrym, Ferry, and mTerra Seed Grant Funds, and the generous contributions by Dr Bruce L. Heflinger.

Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Seyler, L. M., Trembath-Reichert, E., Tully, B. J., & Huber, J. A. Time-series transcriptomics from cold, oxic subseafloor crustal fluids reveals a motile, mixotrophic microbial community. Isme Journal, (2020), doi:10.1038/s41396-020-00843-4.

Description: The oceanic crustal aquifer is one of the largest habitable volumes on Earth, and it harbors a reservoir of microbial life that influences global-scale biogeochemical cycles. Here, we use time series metagenomic and metatranscriptomic data from a low-temperature, ridge flank environment representative of the majority of global hydrothermal fluid circulation in the ocean to reconstruct microbial metabolic potential, transcript abundance, and community dynamics. We also present metagenome-assembled genomes from recently collected fluids that are furthest removed from drilling disturbances. Our results suggest that the microbial community in the North Pond aquifer plays an important role in the oxidation of organic carbon within the crust. This community is motile and metabolically flexible, with the ability to use both autotrophic and organotrophic pathways, as well as function under low oxygen conditions by using alternative electron acceptors such as nitrate and thiosulfate. Anaerobic processes are most abundant in subseafloor horizons deepest in the aquifer, furthest from connectivity with the deep ocean, and there was little overlap in the active microbial populations between sampling horizons. This work highlights the heterogeneity of microbial life in the subseafloor aquifer and provides new insights into biogeochemical cycling in ocean crust.

Description: The Gordon and Betty Moore Foundation sponsored most of the observatory components at North Pond through grant GBMF1609. This work was supported by NSF OCE-1062006, OCE-1745589 and OCE-1635208 to J.A.H. E.T.R. was supported by a NASA Postdoctoral Fellowship with the NASA Astrobiology Institute and a L’Oréal USA For Women in Science Fellowship. The Center for Dark Energy Biosphere Investigations (C-DEBI OCE-0939564) also supported the participation of J.A.H. and B.T. This is C-DEBI contribution number 548.

Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Coskun, O. K., Vuillemin, A., Schubotz, F., Klein, F., Sichel, S. E., Eisenreich, W., & Orsi, W. D. Quantifying the effects of hydrogen on carbon assimilation in a seafloor microbial community associated with ultramafic rocks. Isme Journal. (2021), https://doi.org/10.1038/s41396-021-01066-x.

Description: Thermodynamic models predict that H2 is energetically favorable for seafloor microbial life, but how H2 affects anabolic processes in seafloor-associated communities is poorly understood. Here, we used quantitative 13C DNA stable isotope probing (qSIP) to quantify the effect of H2 on carbon assimilation by microbial taxa synthesizing 13C-labeled DNA that are associated with partially serpentinized peridotite rocks from the equatorial Mid-Atlantic Ridge. The rock-hosted seafloor community was an order of magnitude more diverse compared to the seawater community directly above the rocks. With added H2, peridotite-associated taxa increased assimilation of 13C-bicarbonate and 13C-acetate into 16S rRNA genes of operational taxonomic units by 146% (±29%) and 55% (±34%), respectively, which correlated with enrichment of H2-oxidizing NiFe-hydrogenases encoded in peridotite-associated metagenomes. The effect of H2 on anabolism was phylogenetically organized, with taxa affiliated with Atribacteria, Nitrospira, and Thaumarchaeota exhibiting the most significant increases in 13C-substrate assimilation in the presence of H2. In SIP incubations with added H2, an order of magnitude higher number of peridotite rock-associated taxa assimilated 13C-bicarbonate, 13C-acetate, and 13C-formate compared to taxa that were not associated with peridotites. Collectively, these findings indicate that the unique geochemical nature of the peridotite-hosted ecosystem has selected for H2-metabolizing, rock-associated taxa that can increase anabolism under high H2 concentrations. Because ultramafic rocks are widespread in slow-, and ultraslow-spreading oceanic lithosphere, continental margins, and subduction zones where H2 is formed in copious amounts, the link between H2 and carbon assimilation demonstrated here may be widespread within these geological settings.

Description: This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project-ID 364653263—TRR 235 to WDO and WE, and under Germany’s Excellence Strategy—EXC 2077-390741603. The work was also supported by the Dalio Explore Fund and LMU Mentoring Program. Open Access funding enabled and organized by Projekt DEAL.

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in ISME Journal (2019), doi:10.1038/s41396-019-0373-4.

Description: The benthos in estuarine environments often experiences periods of regularly occurring hypoxic and anoxic conditions, dramatically impacting biogeochemical cycles. How oxygen depletion affects the growth of specific uncultivated microbial populations within these diverse benthic communities, however, remains poorly understood. Here, we applied H218O quantitative stable isotope probing (qSIP) in order to quantify the growth of diverse, uncultured bacterial populations in response to low oxygen concentrations in estuarine sediments. Over the course of 7- and 28-day incubations with redox conditions spanning from hypoxia to euxinia (sulfidic), 18O labeling of bacterial populations exhibited different patterns consistent with micro-aerophilic, anaerobic, facultative anaerobic, and aerotolerant anaerobic growth. 18O-labeled populations displaying anaerobic growth had a significantly non-random phylogenetic distribution, exhibited by numerous clades currently lacking cultured representatives within the Planctomycetes, Actinobacteria, Latescibacteria, Verrucomicrobia, and Acidobacteria. Genes encoding the beta-subunit of the dissimilatory sulfate reductase (dsrB) became 18O labeled only during euxinic conditions. Sequencing of these 18O-labeled dsrB genes showed that Acidobacteria were the dominant group of growing sulfate-reducing bacteria, highlighting their importance for sulfur cycling in estuarine sediments. Our findings provide the first experimental constraints on the redox conditions underlying increased growth in several groups of “microbial dark matter”, validating hypotheses put forth by earlier metagenomic studies.

Description: This work was supported by a grant OR 417/1-1 from the Deutsche Forschungsgemeinschaft, and a Junior Researcher Fund grant from LMU Munich to WDO. This work was performed in part, through the Master’s Program in Geobiology and Paleontology (MGAP) at LMU Munich.