bluuebunny/crossref_metadata_2025 huggingface dataset:
Earth Observation for Surface Melt Monitoring over Antarctic Ice Shelves: Opportunities and Challenges 
Authors: de Roda Husman Sophie , Hu Zhongyang , Lhermitte Stef , Wouters Bert , Kuipers Munneke Peter
Published: March 2022

Surface meltwater is becoming an increasing driver for ice shelf disintegration and consequent mass loss from the AIS. In this regard, monitoring surface melt over Antarctic ice shelves can enhance our understanding of their stability. Earth Observation (EO) satellites provide decadal records of land dynamics over Antarctica, and have been applied in surface melt monitoring. Thereby, they hold a potential to monitor the spatiotemporal evolution of surface melt over the entire AIS. Among the wealth of EO satellites, scatterometer and radiometer observations are most frequently used for surface melt detection, followed by SAR and optical data. Most studies used observations from a single satellite to study surface melt, while specific sensor characteristics (e.g., spatial resolution, overpass time, penetration depth) largely influence the potential for detecting surface melt. Therefore, we compare differences in melt detection between radiometer, scatterometer, SAR and optical sensors to assess the opportunities and challenges in observing surface melt for different EO satellites. We apply state-of-the-art melt detection algorithms to radiometer (Special Sensor Microwave Imager/Sounder, SMMIS), scatterometer (Advanced Scatterometer, ASCAT), Synthetic Aperture Radar (SAR; Sentinel-1), and optical (Moderate Resolution Imaging Spectroradiometer, MODIS) data over the Larsen B+C and Amery Ice Shelves for the 2015-2020 melt seasons. We construct melt timeseries and spatial maps using the melt detection algorithms. and intercompare the spatiotemporal patterns of detected melt. Finally, we compare areas with different melt patterns with auxiliary data sets (i.e., Regional Atmospheric Climate Model (RACMO2), Digital Elevation Models (DEM), high resolution optical imagery). Our results show that the largest differences in detected melt between the EO satellites can be linked to physical properties of the surface, sensor properties and atmospheric conditions. Over the blue ice areas, MODIS indicates more surface melt than the other sensors, as they miss blue ice areas due to either a coarse spatial resolution or the applied detection algorithms. However, over the ice shelves, MODIS detects significantly less surface melt, which can be attributed to the very high cloud obstruction frequency over AIS. Based on this intercomparison, we discuss the opportunities and challenges for melt detection across the AIS regarding the choice of different sensors and the chosen melt detection algorithms. We conclude that merging observations from different satellites (e.g. using machine learning) would further strengthen our knowledge on the presence of surface melt across the AIS, since this combines the strengths of specific sensors based on their sensor characteristics and the area of interest.
TERRANOVA from the last and current Interglacial periods into the Anthropocene: an Atlas database drawing lessons from ancient land use for future European landscape management
Authors: Kluiving Sjoerd , Roche Didier , Zapolska Anhelina , Pearce Elena , Svenning Jens-Christian , Hatlestad Kailin , Lindholm Karl-Johan , Nikulina Anastasia , Scherjon Fulco , Martinez Alexandre , Vella Emily , Serge Maria-Antonia , Mazier Florence , Davoli Marco , Arthur Frank , Renssen Hans , MacDonald Katherine , Roebroeks Wil , Fernandez Nestor
Published: March 2022

TERRANOVA is a Marie Skłodowska-Curie Innovative Training Networks (H2020-MSCA-ITN) project (2019-2023) training 15 PhD students in a new learning initiative between Humanities and Science: Mapping past environments and energy regimes, rethinking human-environment interaction and designing land management tools for policy. TERRANOVA will produce an unprecedented atlas with layers of reconstructed and modelled land-use and vegetation dynamics, climate change and mega-fauna history in Europe from the Eemian (Last Interglacial) and the Holocene from the start up until the present day. This paper describes the intermediate results of two years of research into Atlas building. Communication and data exchange, as well as the process of atlas generation work flow, have been undertaken, including examples of datasets from deep history, ancient landscapes, energy regimes and climate scenarios. The atlas database implements state-of-the-art standards for increasing the interoperability of spatiotemporal datasets. It is currently formed by four main data types: Archaeological data, Climate data, Land cover data, and Megafauna (i.e. large mammals) distribution. The intermediate publication concludes with listing the next steps to stream the Terranova atlas as a tool for communicating the European history of environmental change, including support for future landscape management policies.
Temporal evolution of the background solar wind throughout the inner heliosphere
Authors: Opitz Andrea , Timar Aniko , Nemeth Zoltan , Dalya Zsuzsanna , Koban Gergely , Biro Nikolett , Madar Akos
Published: March 2022

The solar wind properties at a given point in the heliosphere depend strongly on the source surface characteristics, the dynamical effects during propagation and the transient events. We study the background solar wind structures after modelling their propagation throughout the 3-dimensional heliosphere. We remove the transient events from the observations, then apply the ballistic propagation method corrected for pressure gradients at stream interactions. A detailed multi-spacecraft investigation of the radial and latitudinal effects improves our model. These results are applied to study the temporal evolution of the solar wind by excluding the spatial effects through adjusting for the timelag calculated from the spacecraft separations.
Recent evolution of debris-covered glaciers in the Manaslu region of Nepal (1970 - 2019): the case of Ponkar Glacier
Authors: Racoviteanu Adina E. , Glasser Neil F. , Robson Benjamin A. , Harrison Stephan , Millan Romain , Kayastha Rijan B. , Kayastha Rakesh
Published: March 2022

Debris-covered glaciers in the Manaslu region of Nepal have been scarcely studied. Here we aim to fill this gap using new, multi-sensor, freely available 2019 Planet high-resolution (3 to 5 m) imagery, 1970 Corona declassified imagery and UAV and stake ablation data acquired in the field to characterize the surface and evolution of these glaciers over the last five decades. We report regional area changes, glacier thickness, geodetic glacier mass balance and surface velocity changes and focus on Ponkar Glacier and Thulagi Glacier and Lake for an in-depth assessment of surface geomorphology and surface feature dynamics (ponds, vegetation and ice cliffs).

Glaciers in the Manaslu region experienced a mean area loss of -0.26 ± 0.0001 % a-1 between 1970 and 2019, with a mean surface lowering of -0.20 ± 0.02 ma-1 over the period 1970 to 2013, corresponding to a regional geodetic mass balance of -0.17 ± 0.03 m w.e.a−1. Overall, debris-covered glaciers had higher thinning rates compared to clean ice glaciers. During the period 1970 to 2013, the debris-covered Ponkar Glacier had a geodetic mass balance of -0.06 ± 0.01 m w.e.a−1, with parts of the central trunk thickening and a nine-fold increase in the thinning rates over the lower parts of the glacier tongue in the recent years (2013 to 2019). Ice-surface morphology changes between 1970 and 2019 include a decrease in ogives and open crevasses, an increase in ice cliffs and ponds and the expansion of the supraglacial debris and ice-surface vegetation, suggesting reduced ice-dynamic activity.
Towards energy autonomy of small Mediterranean islands: Challenges, perspectives and solutions
Authors: Zisos Athanasios , Pantazi Maria-Eleni , Diamanta Marianna , Koutsouradi Ifigeneia , Kontaxopoulou Anna , Tsoukalas Ioannis , Sakki Georgia-Konstantina , Efstratiadis Andreas
Published: March 2022

The energy autonomy of small non-interconnected islands in the Mediterranean, taking advantage of their high renewable energy potential, has been a long-standing objective of local communities and stakeholders. This is also in line with the recently implemented European Green Deal, which has set the goal of increasing the renewable energy penetration in European countries’ power systems. However, the islands have further challenges than the large-scale inland areas. On the one hand, their population fluctuates significantly across seasons, as result of tourism, which is their key economic activity. The footprint of tourism is a substantial stress to all associated resources and infrastructures during the summer period. On the other hand, most of these areas suffer from both water and land scarcity. These features raise several challenges regarding the development of really autonomous energy systems, based on renewables and essential storage works to regulate the energy surpluses and deficits in the long run. Taking as example the Cycladic island of Sifnos, Greece, we investigate the design of a hybrid power system, combining wind, solar and hydroelectric energy. A major component of the proposed layout is the pumped-storage system. Due to the limited surface water resources of the island, we configure an upper tank at an elevation of 320 m, recycling seawater. This peculiarity introduces a significant level of uncertainty in hydraulic calculations, as well as various technical challenges, such as the erosion of pipes and the electromechanical equipment, and the waterproofing of the tank. An additional challenge is raised by the peculiar wind regime of the island, that makes essential to choose a hub height of turbines to minimize the frequency of power cut-offs. The basis of a rational design procedure for the main system components is the financial optimization that ensures a desirable level of reliability. This is achieved through a stochastic simulation approach that takes into account the stochastic nature of the underlying hydrometeorological drivers (wind velocity and solar radiation) and the energy demand.
Large mammalian herbivores increase the stability of soil carbon in grazing ecosystems
Authors: Naidu Dilip , Bagchi Sumanta
Published: March 2022

Grazing by mammalian herbivores can serve as a climate mitigation strategy as it influences the size and stability of a large soil-C pool (more than 200 Pg C in the world’s grasslands, steppes, and savannas). With the continuing decline in large mammalian herbivores, the resultant loss in grazer functions can be consequential for this soil-C pool, and ultimately for the global carbon cycle. While herbivore effects on the size of the soil-C pool and conditions under which they lead to gains/loss in soil-C are well known, their effects on the equally important aspect of stability of soil-C remain unknown. Also unknown is whether herbivore effects on soil-C and soil-N are related to each other. We use a replicated long-term grazer-exclusion experiment in the Trans-Himalayan ecosystem of northern India to evaluate the consequences of herbivore-loss on the stability of soil-C by quantifying interannual fluctuations (2006-2021). We test how grazers influence the stability of soil-C due to their impacts on both soil-C and soil-N. We find that experimental herbivore-exclusion raises inter-annual fluctuations in both soil-C and soil-N. Importantly, structural equations modelling show that herbivore-exclusion increases the soil-C and soil-N coupling, and weakens the stabilizing effect of soil-N on soil-C. Herbivore-loss, and consequent decline in grazer functions in soil, can therefore undermine the stability of soil-C. Conserving and restoring the functional role of large mammalian herbivores is critical for this valuable ecological service and towards climate mitigation.
Insights into the 3D lithospheric structure below the Sea of Marmara region from seismic tomography and forward gravity modeling
Authors: Fernandez Naiara , Scheck-Wenderoth Magdalena , Bott Judith , Cacace Mauro , Gholamrezaie Ershad
Published: March 2022

The North Anatolian Fault Zone (NAFZ) extends for about 1500 km in the Eastern Mediterranean region, from eastern Anatolia to the northern Aegean. The NAFZ is characterized by strong and frequent seismic activity, increasing the seismic hazard in the region. In the Sea of Marmara area (NW Turkey), the North Anatolian Fault splits into three main branches. The northern branch of the fault, the Main Marmara Fault (MMF), has produced several major earthquakes (M7+) in the past, with a recurrence time of about 250 years. At present, there is a 150 km seismic gap along the MMF which has not ruptured since 1766. The observed fault segmentation, with creeping and locked segments, is indicative of along-strike variability in the fault strength along the seismic gap.

Previous modeling studies in the Sea of Marmara have revealed how crustal heterogeneities effectively affect the thermal and mechanical states of the lithosphere and can likely explain the observed fault segmentation in the area. Therefore, constraining the 3D structure of the deeper crust and upper mantle below the Sea of Marmara is crucial to better assess the mechanical stability of the fault and the possible seismic hazards in the area. In this study, we make use of seismic tomography models and forward gravity modelling to gain insights into the 3D lithospheric structure below the Sea of Marmara. Two tomographic models are used to compute a 3D density model of the area relying on two distinct approaches for the crust and the lithospheric mantle. The results showcase a heterogeneous and rather complex crustal density distribution in the study area[m1] . The 3D density distributions are used in a second step to forward model the gravity response. The results from this new tomography-constrained 3D gravity modelling are then compared to published gravity data and iteratively corrected to fit the overall gravity signals. The final 3D lithospheric-scale density model of the study area will be the basis for thermo-mechanical modeling experiments aimed at improving our current understanding of the present-day geomechanical state of the Sea of Marmara and the MMF and its implications for the seismic hazard of the region.
The impact of reservoir on downstream water quality and pCO2: a case study in Seine Basin, France
Authors: Yan Xingcheng , Thieu Vincent , Garnier Josette
Published: March 2022

The impact of reservoirs on downstream water quality has received widespread attention, but most current studies are based on short-term data only, and less attention has been paid to the impact of reservoirs on downstream carbon dioxide (CO2) concentrations. In the present study, we assessed the nutrient budgets (DIN: dissolved inorganic nitrogen, PO43-: orthophosphate, DSi: dissolved silica) of the reservoirs (Marne, Aube, Seine, and Pannecière reservoirs) in the Seine Basin using long-term dataset (1998-2018), and we also evaluated the reservoir effect on downstream partial pressure of carbon dioxide (pCO2) based on field measurements during 2019-2020. The mean annual retention rates accounted for 16%-53%, 26%-48%, and 22%-40%of the inputs of DIN, PO43-, and DSi in the four reservoirs during the period 1998 to 2018, respectively, showing that the four reservoirs play important roles in nutrient retentions. We further identified that three reservoirs (Marne, Aube, and Seine reservoirs) significantly changed downstream water quality during the emptying period, increasing the concentrations of dissolved organic carbon (DOC) and biodegradable DOC, while lowering the concentrations of DIN, DSi, PO43-, and total alkalinity. Interestingly, we found that the three reservoirs notably decreased downstream pCO2(24%-37%) and enhanced the gas transfer coefficient of CO2 (21%) in downstream rivers compared to the upstream ones, during the emptying period, which highlights the necessity to consider the potential impact of reservoirs on downstream riverine not only for water quality variables, but also for CO2 emissions. Finally, the findings of this study highlight the importance of the combination of biogeochemical and hydrological characteristics to understand the biogeochemical functioning of reservoirs to downstream rivers.
EPOS-Norway Portal
Authors: Michalek Jan , Atakan Kuvvet , Rønnevik Christian , Kverme Sara , Ottemøller Lars , Natvik Øyvind , Langeland Tor , Lampe Ove Daae , Fonnes Gro , Cook Jeremy , Christensen Jon Magnus , Baadshaug Ulf , Kierulf Halfdan Pascal , Grøtan Bjørn-Ove , Olesen Odleiv , Dehls John , Maupin Valerie
Published: March 2022

The European Plate Observing System (EPOS) is a European project about building a pan-European infrastructure for accessing solid Earth science data, governed now by EPOS ERIC (European Research Infrastructure Consortium). The EPOS-Norway project (EPOS-N; RCN-Infrastructure Programme - Project no. 245763) is a Norwegian project funded by National Research Council. The aim of the Norwegian EPOS e‑infrastructure is to integrate data from the seismological and geodetic networks, as well as the data from the geological and geophysical data repositories. Among the six EPOS-N project partners, four institutions are providing data – University of Bergen (UIB), - Norwegian Mapping Authority (NMA), Geological Survey of Norway (NGU) and NORSAR.

In this contribution, we present the EPOS-Norway Portal as an online, open access, interactive tool, allowing visual analysis of multidimensional data. It supports maps and 2D plots with linked visualizations. Currently access is provided to more than 300 datasets (18 web services, 288 map layers and 14 static datasets) from four subdomains of Earth science in Norway. New datasets are planned to be integrated in the future. EPOS-N Portal can access remote datasets via web services like FDSNWS for seismological data and OGC services for geological and geophysical data (e.g. WMS). Standalone datasets are available through preloaded data files. Users can also simply add another WMS server or upload their own dataset for visualization and comparison with other datasets. This portal provides unique way (first of its kind in Norway) for exploration of various geoscientific datasets in one common interface. One of the key aspects is quick simultaneous visual inspection of data from various disciplines and test of scientific or geohazard related hypothesis. One of such examples can be spatio-temporal correlation of earthquakes (1980 until now) with existing critical infrastructures (e.g. pipelines), geological structures, submarine landslides or unstable slopes. 

The EPOS-N Portal is implemented by adapting Enlighten-web, a server-client program developed by NORCE. Enlighten-web facilitates interactive visual analysis of large multidimensional data sets, and supports interactive mapping of millions of points. The Enlighten-web client runs inside a web browser. An important element in the Enlighten-web functionality is brushing and linking, which is useful for exploring complex data sets to discover correlations and interesting properties hidden in the data. The views are linked to each other, so that highlighting a subset in one view automatically leads to the corresponding subsets being highlighted in all other linked views.
New imaging strategies for constraining upper mantle anisotropy with teleseismic P- and S-wave delay times
Authors: VanderBeek Brandon
Published: March 2022

Teleseismic travel-time tomography remains one of the most popular methods for obtaining images of Earth's upper mantle. However, despite extensive evidence for a seismically anisotropic mantle, assuming an isotropic Earth remains commonplace in such imaging studies. This assumption can result in significant imaging artefacts which in turn may yield misguided inferences regarding mantle dynamics. Using realistic synthetic seismic datasets produced from waveform simulations through elastically anisotropic geodynamic models of subduction, I show how such artefacts manifest in teleseismic P- and S-wave tomography. The anisotropy-induced apparent anomalies are equally problematic in both shear and compressional body wave inversions and the nature of the shear velocity artefacts are dependent on the coordinate system in which the delay times are measured. In general, the isotropic assumption produces distortions in slab geometry and the appearance of large sub- and supra-slab low-velocity zones. I summarise new methods for inverting P- and S-delay times for both isotropic and anisotropic heterogeneity through the introduction of three anisotropic parameters that approximate P and S propagation velocities in arbitrarily orientated hexagonally symmetric elastic media. Through a series of synthetic tomographic inversions, I demonstrate that both teleseismic P- and S-wave delay time data can resolve complex anisotropic heterogeneity likely present in subduction environments. Moreover, including anisotropic parameters into the inversions improves the reconstruction of true isotropic anomalies. Particularly important to the removal of erroneous velocity structure is accounting for dipping fabrics as many imaging artefacts remain when simpler azimuthal anisotropy is assumed. I conclude by highlighting results from recent applications of the anisotropic imaging method to P-wave datasets in the Western US and Mediterranean.
Robustness and singularity of pre-seismic signals in GRACE gravity solutions: application to the 2011 Tohoku Mw9.0 Earthquake
Authors: Panet Isabelle , Narteau Clément , Lemoine Jean-Michel , Bonvalot Sylvain , Remy Dominique
Published: March 2022

Documenting the preparation phase of giant earthquakes and retrieving pre-seismic signals of upcoming events is a crucial challenge. Over the short term, various deformation transients have been detected before large subduction events, emphasizing in particular the role of the slab pull in driving plate motions (e.g., Bouchon et al., 2016 ; Bedford et al., 2020). Among them, we previously evidenced an anomalous gravity gradient signal during the months before the March 2011 Tohoku earthquake, likely originating from the solid Earth (Panet et al., 2018). We showed that it could reflect a broad deformation of the subducted slab prior to the event, generating the giant earthquake as the deformation propagated from depth to surface.

Taking the example of the 2011 Tohoku earthquake, we conduct here a systematic and global retrospective analysis of time series of GRACE-reconstructed gravity gradients truncated in February 2011. Our aim is to test whether the gravity gradient variations preceeding the earthquake can be identified as singular and potentially originating from the solid Earth in an automated way and without knowledge on the upcoming event. First, we enhance the angular resolution of the gravity gradients in order to extract signals closely aligned with a chosen plate boundary orientation. Along this preferred orientation, we extract fast temporal variations at the sub-annual timescales of geodetic, gravitational and seismic signals reported before the event in previous studies. To evaluate the significance of the obtained gravity gradient anomalies, we design a method to extract coherent signals between different GRACE gravity field models and assess their sensitivity to the dealiasing ocean model. We present and discuss the results of these analyses applied to different sets of GRACE gravity models: the GRGS03, GRGS04 and CSR06 solutions, as well as their respective ocean dealiasing models. Beyond the case of the Tohoku earthquake, our approach can be applied to the systematic monitoring of the Pacific subduction belt, to detect gravity variations potentially linked with sudden changes in slab motions in-depth these plate boundaries.

 

References

Bedford, J. R., et al. (2020). Months-long thousand-kilometre-scale wobbling before great subduction earthquakes, Nature 580, 628-635.

Bouchon, M., et al.  (2016). Potential slab deformation and plunge prior to the Tohoku, Iquique and Maule earthquakes, Nature Geoscience 9, 380-383.

Panet, I., et al. (2018). Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data, Nature Geoscience 11, 367-373.
Should I grow or should I go? - Transcriptomic responses of permafrost soil microbiomes to sudden thaw and erosion
Authors: Scheel Maria , Zervas Athanasios , Jacobsen Carsten Suhr , Christensen Torben Røjle
Published: March 2022

Permafrost soils usually remain frozen in summer, often even for millennia. Due to low temperatures, decomposition rates are low and alone Arctic permafrost is estimated to store 1850 Gt carbon (C). This currently corresponds to about twice the amount of atmospheric CO2. While microorganisms within their seasonally thawing surface (active) layer are adapted to enormous temperature fluctuations, the intact permafrost microbiome contains spore-formers and extremophiles at low metabolic states. With global warming, seasonal thaw depth increases, not only leading to loss of ancient communities, but also to a growing availability of soil carbon for decomposition. Much of permafrost microbial taxonomic and metabolic diversity is unknown still, but our most urgent gaps of knowledge exist in monitoring this vulnerable microbiome’s ecological and metabolic adaptation in situ during permafrost thaw and erosion. Insights about microbial carbon sequestration in thawing soils is crucial - yet understudied, as permafrost environments are usually remote and modern sequencing techniques require elaborate sample storage and transport.

Here, we present our results of total RNA sequencing of abruptly eroding as well as intact 26200-year-old permafrost soils, from the high Arctic Northeast Greenland. Gene expression of samples describes the community composition (rRNA) and active metabolic pathways (mRNA) in zones of intensely degrading permafrost. The impact of changing physicochemical soil parameters with depth, such as pH, age, soil moisture and organic matter content was compared to determine possible metabolic and community-level responses. We revealed taxonomic composition and diversity, as well as metabolic pathways of microbial organic carbon remineralization especially at the crucial freshly thawed permafrost depths.
Exploring local perceptions of water quality in the upper Santa River, Peru
Authors: Rangecroft Sally , Dextre Rosa Maria , Richter Isabel , Kelly Claire , Turin Cecilia , Fuentealba Beatriz , Grados Bueno Claudia V. , Camacho Hernández Mirtha , Morera Sergio , Martin John , Guy Adam , Clason Caroline
Published: March 2022

Water quality is an integral part of water security, but water quality itself is complex, due to its multifaceted nature. Measuring the physico-chemical indicators for water quality (e.g. pH, turbidity, heavy metal content) can provide an objective picture of water health, but it does not provide information on how it integrates and expresses the human perspective. Perceptual information and local ecological knowledge on water quality can help to understand the usability of water and support better conservation strategies. Therefore, the aims of the Nuestro Rio project were to investigate local perceptions of water quality in the upper Santa River basin, Peru. Walking interviews (n = 99) were conducted in the field between July-August 2021 to assess community members perceptions of their local rivers and streams. Through qualitative data analysis in two rural communities in the glaciated Santa River basin, we collected local perspectives on good and poor water quality, identified some of the key water concerns of the population, and explored the importance of emotions for determining water quality perceptions. Overall water quality perspectives differed within, and between, the two communities. Yet, it was possible to identify several characteristics and concerns that the population has been perceiving in recent years, as well as their causes, both natural and anthropogenic. Both communities felt the main cause of poor water quality was pollution due to the presence of minerals in the water, “invisible” aspects of water quality. We found that local perceptions on water quality also depend on water use as it has an important effect on local organisation. Emotions, on the other hand, reflect the population’s concern, fear, anger, and even frustration, when perceiving poor water quality, and happiness, trust, and even affection, when perceiving good water quality. More inclusive science that asks people what they observe, think and feel about the quality of their rivers and water can help provide a much deeper contextual understanding (e.g. useability of water, changes over time, traditional ecological knowledge) of local dynamic human-water systems, and improve science communication and policy implementation.
Analysis of support media in packaged bioreactors for landfill leachate treatment systems 
Authors: Gómez Zully , Solano Johanna , Orjuela David , Rodrigo María , Rodrigo Javier
Published: March 2022

One of the primary environmental problems connected to the growth of cities is the proportional increase of solid waste production and the corresponding leachate generation in the final disposal sites. A research line on the definition of technical systems that facilitate the proper treatment of these leachates to minimize groundwater, surface water, air and soil pollution is currently being developed.

One of the leachate-treatment alternatives is installing biofilm anaerobic biological reactors, in which microorganisms take charge of degrading organic matter while minimizing the leachate pollutant load. Optimal conditions are sought to develop this technology in order to achieve the highest bioreactor efficiency. Variables such as pH, temperature, retention time and the support media where the biofilm will be formed must be considered, in addition to its design and the material use to make it.

Therefore, the support media is one of the most important factors in anaerobic biofilm reactors design, given its function of creating the surface where the microorganisms adhere to form the biofilm. A proper design of this packing facilitates having a greater surface area per unit volume, thus increasing contact with the microorganisms, which is expected to increase the removal rate. Taking this into account, this study analyzes the types of materials currently used for packaging, along with their efficiency in biofilm reactors for first-stage leachate treatment. The evaluation is made using a specific polymeric material composed of polyethylene and expanded polystyrene waste as support media for bioreactors
Lab lysimeter disaggregated ET data for the validation of a two-source model
Authors: Paciolla Nicola , Corbari Chiara , Mancini Marco
Published: March 2022

One of the main issues with obtaining accurate Evapotranspiration (ET) measurements for heterogeneous crops is managing the partition between the contribution of bare soil / cover crop and that of the main crop. Mostly, ET estimates are obtained as an aggregate of the two components, as direct measurements of distinct Evaporation (E) and Transpiration (T) are possible only with high-accuracy and time-costly field lysimeters. Hydrological modelling can provide these kinds of estimates, with the dichotomy between single-source (one energy balance equation for the whole pixel) and two-source (one balance equation each for the vegetated and the non-vegetated pixel fraction) models approaching the problem from different perspectives. In this work, a laboratory lysimeter was employed to obtain disaggregated fluxes from a global ET value and use them to validate the partitioned estimates from a two-source version (FEST-2-EWB) of the single-source FEST-EWB distributed hydrological model, which was also included in the validation as a reference. The lysimeter was sown with grass distributed in three rows, alternated with similar rows of bare soil, with irrigation being provided to the former and not to the latter. Thermal imagery from proximal sensing observations was used to calibrate the models. Two boxes were placed on the lysimeter, one completely vegetated and the other left bare. These boxes were periodically weighted separately from the lysimeter, obtaining accurate measurements of their ET, that were then scaled back to the correspondent areas in the main lysimeter. The model runs, provided similar calibration performances, showed similar global ET values, close to those measured over the lysimeter, but diverged when looking ad transpiration alone. The two-source model offered estimates much closer to those derived from the lysimeter than the single-source model.
Assessing long-term microbial impact on mineralogical trapping of uranium from deep groundwater at Äspö Hard Rock Laboratory, Sweden
Authors: Pidchenko Ivan , Christensen John , Puigdomenech Ignasi , Ignatyev Konstantin , Drake Henrik
Published: March 2022

Natural uranium (U) in deep groundwater has been extensively studied in connection to the search for suitable locations for final disposal of spent nuclear fuel (SNF).[1] The U removal process depends on environmental and geochemical conditions and is often associated with fractionation of the main ‘stable’ isotopes, 238U and 235U (δ238U). The latter thus serves as an important tracer for redox specific scenarios, in local to global temporal and spatial scales. In this contribution, one specific borehole drilled at 415 m depth into Paleoproterozoic granitoid rock at the Äspö Hard Rock Laboratory (HRL), Sweden, is investigated after 17-year experiment period (1995-2012).[2] The HRL is built and operated by the Swedish Nuclear Fuel and Waste Management Co. and serves as a full-scale tunnel as a test-facility for the actual SNF repository to be built at Forsmark. We show how various micro-analytical techniques, modelling methods, and isotope analyses can be utilized to reveal U speciation and removal pathways, associated redox changes and related U isotope fractionations in the deep aquifer and during U mineralogical trapping. Spectroscopic techniques reveal that calcite precipitated on the borehole equipment contains intermittent highly elevated U, occurring as U(IV), and thus serves as a sink for U. Thermodynamic modelling shows that aqueous Fe(II) is the main driving force for the reduction of U(VI) in the borehole water, alongside sulfides formed from bacterial sulfate reduction. The bacteria-driven degradation of technical polymer constituents present in the borehole equipment is central to processes forming the sulfides and carbonates that facilitate reduction of U(VI) and subsequent immobilisation of U(IV) into the calcite. We use δ238U to show that U undergoes several redox events in granitic rock aquifers, involving mineralogical and microbial pathways. The recorded δ238U provides evidence for reductive removal of U from fracture water, presumably taking place along redox fronts in the fracture network. The obtained data on U(IV) removal by calcite provide important insights for the assessment of the geochemical behaviour of U and other redox-sensitive species in deep anoxic aquifers, that is relevant for trace metal mobility and long-term storage of SNF and nuclear waste.

References

[1]. J. Suksi et al., (2021), Chemical Geology 584: 120551.

[2]. H. Drake et al., (2018), Environmental Science & Technology 52(2): 493-502.
Cross-divide topographic contrasts created by asymmetrical glaciation: A case study from the northeastern Qilian Shan
Authors: Lai Jingtao , Huppert Kimberly
Published: March 2022

Drainage divide migration has drawn growing attention in recent years because it can induce changes in drainage areas and confound inference of spatial or temporal changes in tectonic or climatic forcing from river profiles. Recent studies have used different metrics of divide stability, such as cross-divide contrasts in topography, to quantify a divide’s susceptibility to migration. These metrics are based on expectations of cross-divide differences in fluvial or hillslope erosion rates, yet glacial erosion may be the primary driver of topographic evolution and drainage reorganization in many mid-latitude mountain ranges. Here we report a case study in the northeastern Qilian Shan, a northwest-southeast-trending mountain belt on the northeast margin of the Tibetan Plateau. The northeast-facing range front in Qilian Shan today receives less solar insolation but more summer monsoonal precipitation than the southwest-facing front and thus hosts more small, high elevation valley glaciers. We quantify cross-divide contrasts in topography using different metrics and find stronger glacial modification of topography on northeast-facing slopes than on southwest-facing slopes. The northeast-facing range front displays oversteepened U-shaped valleys and evidence of extensive Quaternary glaciation, whereas the southwest-facing front is incised by V-shaped valleys that hosted only small Quaternary glaciers. Near the drainage divide, valleys on the northeast-facing front have steeper headwalls and higher headwall relief than valleys on the southwest-facing front. Based on these observations, we proposed a conceptual model of divide migration in the northeastern Qilian Shan: during the last glacial period, strong glacial modification on the northeast-facing range front caused headward expansion of valleys and drove southwestward divide migration. Since the onset of the present interglacial period, faster postglacial hillslope processes in northeast-facing valleys have sustained this southwestward divide migration. We develop a numerical model to test this conceptual model and discuss the impact of Quaternary glaciation on drainage reorganization in the Qilian Shan. We suggest that Quaternary glaciation and following postglacial adjustment have important impacts on divide migration and drainage reorganization in mid-latitude mountain ranges.
Measurements of cosmic rays by a mini neutron monitor aboard the German research vessel Polarstern.
Authors: Heber Bernd , Banjac Sasa , Burmeister Sönke , Zoska Martin , Giese Hanna , Herbst Konstantin , Romaneehsen Lisa , Schwerdt Carolin , Stauss Dutoit , Wallmann Carsten , Vogt Adrian , Walter Michael
Published: March 2022

Galactic cosmic rays (GCRs) consist of energetic electrons and nuclei which are a direct sample of material from far beyond the solar system. Measurements by various particle detectors have shown that the intensity varies on different timescales, caused by the Sun’s activity and geomagnetic variation. Interplanetary disturbances cause space weather effects which warrant a more detailed study. Many studies on GCR intensity decreases is based on the analysis of ground-based neutron monitors and muon telescopes. Their measurements depend on the geomagnetic position, and the processes in the Earth's atmosphere. In order to get a better understanding of the geomagnetic filter over the solar cycle, the Christian-Albrechts-Universität zu Kiel, DESY Zeuthen, and the North-West University in Potchefstroom, South Africa agreed on a regular monitoring of the GCR intensity as a function of latitude, by installing a portable device aboard the German research vessel Polarstern in 2012. The vessel is ideally suited for this research campaign because it covers extensive geomagnetic latitudes (i.e. goes from the Arctic to the Antarctic) at least once per year. Here we present the measurements for different latitude surveys including the periods of solar maximum in 2014 and solar minimum in 2019. 

The Kiel team received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405. The team would like to thank the crew of the Polarstern and the AWI for supporting our research campaign.
Aerosol-cloud interactions over the central Arctic Ocean
Authors: Zieger Paul , Karlsson Linn , Baccarini Andrea , Duplessis Patrick , Baumgardner Darrel , Brooks Ian M. , Chang Rachel , Dada Lubna , Dällenbach Kaspar R. , Krejci Radovan , Leaitch W. Richard , Leck Caroline , Salter Matthew E. , Wernli Heini , Wheeler Micheal J. , Schmale Julia
Published: March 2022

The physical and chemical properties of aerosol particles are important for the formation of cloud droplets and ice crystals. This is especially true for pristine regions such as the Arctic, where particle number concentrations are often very low. Observations from these regions are still sparse due to the technical challenges involved.

Here, we present recent results of detailed in-situ observations of aerosols and clouds performed on board the Swedish icebreaker Oden over the central Arctic Ocean in 2018. We show that Aitken-mode particles, i.e. particles below 70 nm diameter, contribute significantly to cloud-forming particles (here termed cloud residuals), especially towards autumn with the start of the freeze-up of the sea ice. These cloud-forming Aitken-mode particles coincided with air that spent more time over the ice, while accumulation-mode dominated cloud residuals showed more of an oceanic influence, as shown using air back trajectory analysis. At the same time, the Aitken-mode dominated cloud residuals were associated with changes in the average chemical composition of the accumulation mode showing an increased organic contribution, in contrast to the accumulation-mode dominated cloud residuals, which showed an increased sulfate contribution. The Hoppel-minima in both whole-air and cloud residual size distributions was almost unchanged, suggesting only little addition of aerosol mass due to aqueous-phase cloud processing. Our highly detailed observations of aerosol-cloud interactions over the central Arctic Ocean close to the North Pole provide valuable insights into the properties and the origin of particles that are relevant for cloud formation in this remote region of our planet.

This work is currently in review at the Journal of Geophysical Research (JGR).
A Touch of Space Weather - Outreach project for visually impaired students
Authors: Zychova Lenka , Lefever Karolien , Crosby Norma
Published: March 2022

'A Touch of Space Weather' is a project that brings space weather science into the hands of blind and visually impaired (B&VI) high-school students. This project was awarded an EGU Public Engagement Grant in 2021.

The goal of our project is to offer B&VI teachers a new approach to teaching complex STEM topics in a creative way. One of the main activities is the creation of audio booklets, a type of media in high demand by B&VI teachers. These audio booklets address various scientific topics that are taught in science classes in general high schools, such as the Sun, Earth's magnetic field, Moon exploration, and more.

This project wants to highlight the importance of space weather, as it influences nearly every aspect of our modern life ranging from banking, navigation, telecommunications to the power supply. It is an interdisciplinary subject and therefore ideal for explaining complex scientific topics to students while at the same time teaching them space- and geo-sciences. That is why each audio booklet includes a description of a space weather phenomenon or effect relevant to the topic.

3D printed models and a tactile image provide hands-on activities to complement the audio lessons. The EGU Public Engagement Grant is covering the physical costs of creating a minimum of 30 ‘A Touch of Space Weather’ boxes that will be distributed to the schools and organizations that are providing education to B&VI people. Each box will include material for one tactile image, one USB stick with all audio booklets, assignments for students, and 3D printed models to accompany audio booklets.
Statistical study of the ripples and reformation in the collisionless shocks using MMS observation
Authors: Lotekar Ajay , Khotyaintsev Yuri , Graham Daniel , Dimmock Andrew , Lalti Ahmad , Johlander Andreas
Published: March 2022

Collisionless shocks are ubiquitous throughout the universe in near-Earth and astrophysical plasma environments. The behavior of collisionless shocks in terms of their structure and energy dissipation has been the subject of extensive research over many decades, but many open questions remain. Recent studies have demonstrated that the Earth's bow shock can exhibit ripples that propagate along the shock surface. However, their occurrence, dependence on shock parameters, and their role in shock dynamics is still under investigation. One signature of rippling is the presence of phase space holes in reduced ion distribution (integrated along the tangential plane of the shock). Such ion phase space holes are also observed in association with the shock reformation. It is unclear at what part of the parametric space these ion phase space holes are expected. In this study, we have focused on characterizing ion phase space holes at the Earth’s bow shock using MMS observations. We analyze more than 500 shock crossings observed by the MMS spacecraft and establish a systematic procedure to find the shocks exhibiting phase space holes. We investigate the key shock physical processes responsible for the existence of these phase space holes (e.g. ripples and reformation) and study the association to shock parameters such as Mach number and geometry. We present the first statistical study of this nature, and these results are important to understanding the non-stationary behavior of collisionless shocks. 
Capturing stress legacy: From tree physiology to forest resilience  
Authors: Ruehr Nadine
Published: March 2022

Extreme droughts combined with heatwaves are intensifying in frequency and severity. The impacts on tree and forest functioning are manifold, and span from declining tree growth to reduced forest health and tree die-back as observed in many regions world-wide. These detriments have clear consequences for the well-documented contemporary carbon dioxide sink of forests and hence, their role in buffering climate change. Yet to date, we lack a comprehensive understanding to quantify long-term impacts on forest resilience and productivity beyond specific individual stress events. A striking knowledge-gap persists on what determines tree recovery and survival following drought release, including the thresholds causing functional damage and the role of repair mechanisms. Here, novel insights into physiological thresholds and post-stress recovery focusing on tree hydraulic processes and carbon metabolism are presented. A conceptual framework indicates that the persistence of stress legacy depends and on the degree of functional impairment, for instance hydraulic dysfunction or leaf senescence, and the ability for repair and regrowth. I argue that an improved physiological understanding of thresholds resulting in functional damage and how fast trees can repair and/or regrow tissues provides a promising avenue in order to integrate stress legacy into forest ecosystem models.