bluuebunny/crossref_metadata_2025 huggingface dataset:
A procedure to characterize physical and chemical molecular properties of individual organic matter particles
Authors: Estévez Edurne , Mützel Sophia , del Campo Rubén , Stalder Roland , Singer Gabriel
Published: February 2023

Rivers are important contributors to the global carbon cycle as they actively transform terrestrial organic matter (OM) during transport to the oceans. The efficient OM processing results from a diverse assemblage of consumers including heterotrophic microbes (i.e., fungi, bacteria and protists) and macroinvertebrates, which interact with an equally diverse pool of OM. Ecologically, OM can be understood as forming a multidimensional resource space for consumers, whose understanding, however, requires an advanced capability to describe relevant dimensions (i.e., traits of OM) at a level that matches the resolution of consumer diversity, where significant advancement is generated by molecular biological means (i.e., DNA sequencing). This implies moving beyond proxy-based indirect descriptors (e.g., indices derived from absorbance or fluorescence spectroscopic analyses), integrative bulk property measures (e.g., C, N, P, lignin, tannins and fibre content) or bulk amounts of operational size fractions (e.g., dissolved, fine and coarse particulate OM). Recent technological advances such as size-exclusion, liquid or ion chromatography coupled to mass spectrometry have allowed to describe dissolved OM (DOM) on a molecular species level, setting a great step forward in the highly resolved description of DOM properties. However, particulate OM (POM) characterization remains behind significantly. Here, a per-particle basis description with regard to physical features and macromolecular composition is needed. We propose a procedure to asses both physical and chemical molecular properties of individual POM particles by combining (i) photometrical techniques, which are based on image processing and particle analysis (e.g., ImageJ) of pictures obtained with microscopes or cameras, and (ii) attenuated total reflectance infrared spectroscopy (ATR-FTIR) to measure particle-specific chemical composition. We apply this method to POM samples collected along large-scale environmental gradients in river networks.
Sea state contribution to steric sea-level
Authors: Bonaduce Antonio , Pham Nam , Staneva Joanna , Grayek Sebastian , Raj Roshin P. , Breivik Øyvind
Published: February 2023

The effect of wave-induced processing on steric sea-level is investigated through ocean-wave coupled simulations. The experiments are performed with a high-resolution configuration of the Geestacht COAstal model SysTem (GCOAST), implemented in the Northeast Atlantic, the North Sea and the Baltic Sea which are considered as connected basins. The GCOAST system accounts for wave-ocean interactions and the ocean circulation relies on the NEMO (Nucleus for European Modelling of the Ocean) ocean model, while ocean-wave simulations are performed using the spectral wind wave model WAM. The objective is to quantify the sea-state contribution to steric sea-level variability and trend over a 26-year period (1992-2017). The ability of wave-ocean coupled simulations to disclose the sea-state contributions to sea-level variability and surge is demonstrated. The contribution of the wave-induced processes (WIPs) to the sea surface dynamics (e.g. temperature and salinity), ocean mixing (mixed layer thickness), and on the modulation of air-sea fluxes (e.g. heat flux) clearly appear both during winter (10-20 %) and summer (10 %), which in turn affect the steric sea-level variability. Investigating the components of steric sea-level signal, the thermosteric sea-level shows larger amplitudes compared to the halosteric component. Significant contributions to the thermosteric sea-level variability (40 %) due to wave-induced processes are observed in the North Atlantic (in summer) and along the Norwegian Trench (in winter). WIPs influence the thermosteric sea-level trends in the North Atlantic up to the order of 1 mm yr-1, both during winter and summer, in the open ocean and at the shelf break, while smaller contributions are observed over the shelf areas of the North Sea.
Six-component wave type fingerprinting and filtering
Authors: Sollberger David , Bradley Nicholas , Edme Pascal , Robertsson Johan O. A.
Published: February 2023

We present a technique to automatically classify the wave type of seismic phases that are recorded on a single six-component recording station (measuring both three components of translational and rotational ground motion) at the earth's surface. We make use of the fact that each wave type leaves a unique 'fingerprint' in the six-component motion of the sensor. This fingerprint can be extracted by performing an eigenanalysis of the data covariance matrix, similar to conventional three-component polarization analysis. To assign a wave type to the fingerprint extracted from the data, we compare it to analytically derived six-component polarization models that are valid for pure-state plane wave arrivals. For efficient classification, we make use of the supervised machine learning method of support vector machines that is trained using data-independent, analytically-derived six-component polarization models. This enables the rapid classification of seismic phases in a fully automated fashion, even for large data volumes, such as encountered in land-seismic exploration or ambient noise seismology. Once the wave-type is known, additional wave parameters (velocity, directionality, and ellipticity) can be directly extracted from the six-component polarization states without the need to resort to expensive optimization algorithms.We illustrate the benefits of our approach on various real and synthetic data examples for applications such as automated phase picking, aliased ground-roll suppression in land-seismic exploration, and the rapid close-to real time extraction of surface wave dispersion curves from single-station recordings of ambient noise. Additionally, we argue that an initial step of wave type classification is necessary in order to successfully apply the common technique of extracting phase velocities from combined measurements of rotational and translational motion.
Effect of stress regime change on fractured carbonate’s permeability: A case of Latemar carbonate buildup (The Dolomites, Northern Italy)
Authors: Igbokwe Onyedika Anthony , Timothy Jithender , Kumar Ashwani , Yan Xiao , Mueller Mathias , Verdecchia Alessandro , Meschke Günther , Immenhauser Adrian
Published: February 2023

Changes in stress regimes impact the geometry of fracture networks and affect the porosity and permeability of carbonate reservoirs. This is, predominantly, because of the complexity of the deformation phases, the poor understanding of the mechanical and diagenetic mechanisms that affect apertures, and the difficulty in precisely characterizing aperture distributions in the subsurface. Utilizing outcrop data analysis and displacement-based linear elastic finite element modelling, we study the effect of stress regime change on fracture network permeability. The model is based on fracture networks, specifically fracture sub-structures.The Latemar, which is primarily affected by subsidence deformation and Alpine compression, is used as an outcrop analogue for isolated (Mesozoic) carbonate formations with fracture-dominated permeability. We apply a novel strategy involving two compressive boundary loading conditions constrained by the study area's NW-SE and N-S stress directions. Stress-dependent heterogeneous apertures and effective permeability were computed by: (i) using the local stress state within the fracture sub-structure and (ii) running a single-phase flow analysis considering the fracture apertures in each fracture sub-structure.Our results show that the impact of the modelled far-field stresses at: (i) subsidence deformation (first stage loading) from the NW-SE, and (ii) Alpine deformation (second stage loading) from the N-S, increased the overall fracture aperture and permeability. In each case, increasing permeability is associated with open fractures parallel to the orientation of the loading stages and with fracture densities. The anisotropy of permeability is affected by shear dilation and is increased by the density and connectedness of the fracture network. The two far-field stresses simultaneously acting within the selected fracture sub-structure at a different magnitude and orientation do not necessarily cancel out each other in the mechanical deformation modelling. These stresses effect the overall aperture and permeability distributions. These effects, which may be ignored in simpler stress-dependent permeability, can result in significant inaccuracies in permeability estimation, especially in the subsurface carbonate reservoirs.
Temperature control on biochar decomposition in soil - implications for long-term carbon sequestration
Authors: Elsgaard Lars , Eriksen Rikke Lykke
Published: February 2023

Biochar is an aspirational strategy for long-term carbon sequestration in soil, emergent in guidelines by the Intergovernmental Panel on Climate Change (IPCC). Yet, the rate and pathways of biochar mineralization remain uncertain, and information is scarce on the role of soil temperature. Recent studies predicting the 100-yr stability of biochar in soil use a profile of temperature sensitivity (Q10) for biochar mineralization that deviates markedly from common biochemical temperature relationships, especially at mean annual temperatures of 0-10°C, which prevail in many temperate soils. Here, we compared estimates of biochar stability using (i) empirical Q10 data and (ii) Arrhenius activation energies for biochar mineralization similar to those for other recalcitrant biomolecules. The results indicate that empirical Q10 data used so far overestimate the long-term stability of biochar in soils at 0-10°C, but underestimate the stability at >10°C. The size of these effects increases with higher molar ratio of hydrogen to organic carbon (H/Corg) in the biochar, meaning that predictions for labile biochars are more uncertain. We conclude that care should be taken when normalizing biochar stability data to prevailing soil temperatures and call for further studies to document the temperature sensitivity of biochar mineralization
Monsoon-triggered landslide timings derived from Sentinel-1 reveal cloudburst triggering and suggest earthquake-induce hillslope weakening
Authors: Burrows Katy , Marc Odin
Published: February 2023

Heavy rainfall events in mountainous areas can trigger thousands of destructive landslides, which pose a risk to people and infrastructure and significantly affect the landscape. In Nepal, monsoon rainfall triggers hundreds of landslides across the country every year and represent a large share of total sediment production. However, a persistent problem is that monsoon-induced landslides are mapped using multi-spectral satellite images, where cloud cover makes it impossible to constrain precisely landslide timing. This has hampered our understanding of how rainfall is driving landsliding during the monsoon and how the hillslope susceptibility to rainfall could be modulated after earthquakes. Sentinel-1 SAR images offer a solution to this problem since SAR can be acquired through cloud cover, is sensitive to landslides, and the regular acquisition strategy of the satellite means that images are acquired every 12 days on two tracks globally. A newly developed method based on Sentinel-1 amplitude time series can be used to assign 12-day time windows for 30% of the landslides in an inventory (Burrows et al., NHESS, 2022).We apply this method to optically-derived inventories of monsoon triggered landslides across Nepal from 2015-2019, obtaining timing information for hundreds of landslides during this period. We use this new landslide timing information alongside satellite rainfall data (GPM IMERG calibrated using rain gauges to better account for orographically-induced precipitation) to further our understanding of landslide triggering during the monsoon. We are able to identify spatio-temporal clusters of landslides that are concurrent with intense peaks in rainfall during the 2017 and 2019 monsoon seasons. This suggests that cloudburst events during the monsoon can drive a large share of the mass-wasting volume associated with a given year.We also observe that, during the 2015 monsoon season, a large number of landslides failed earlier and after much less rainfall than in 2017-2019. This may reflect weakening of the hillslope following the Mw 7.8 Gorkha earthquake, which occurred around six weeks before the onset of the monsoon season in 2015, triggering co-seismic landslides across central and eastern Nepal and resulting in elevated numbers of landslides during the 2015 monsoon. Using the satellite rainfall data, we model the evolution of soil water content through time for every landslide. By using the modelled soil moisture at the time of failure in the Factor of Safety equation, we can obtain an estimate of cohesion for every landslide. By comparing cohesions for the 2015 dataset against those from 2017-2019, we suggest that the early landsliding in 2015 could be explained by a cohesion loss of 1-5 kPa.
Persistence of subsoil compaction and potential for natural recovery in a sandy loam soil
Authors: Arthur Emmanuel , Fouladidorhani Maliheh , Yan Fulai , Nazari Meisam , Nawaz Muhammad Mohsin , Munkholm Lars , Lamandé Mathieu
Published: February 2023

Mechanization operations in agriculture have, for the last two decades, involved consistently higher wheel loads with an increased risk of soil compaction, particularly in the subsoil. Subsoil compaction is more persistent compared to the topsoil due to limited mitigation options. There is, however, a potential for the natural recovery of compacted subsoils through processes such as freeze-thaw and wet-dry cycles, and biological activity. The objectives of the present study were to (i) quantify the persistent effects of subsoil compaction on subsoil pore characteristics and water flow, based on visual and quantitative methods, and (b) investigate the potential for natural recovery nine years after the compaction event.Soil compaction was achieved by tractor-trailer combinations for slurry application with a maximum wheel load of 8 Mg on a loamy Luvisol. The compacted plots were trafficked annually for four years (2010-2013). Nine years later (2022), field measurements (saturated hydraulic conductivity, visual evaluation of subsoil structure [SubVESS], and penetration resistance) were conducted at a depth of 0.3-0.4 m. Additionally, undisturbed samples of 100 cm3 were taken for measurements of gas flow (air permeability [ka] gas diffusivity [Dp/Do], and air-filled porosity[ε]) after equilibration at a matric potential of −100 hPa. The negative impact of compaction on the measured variables was compared to previous measurements conducted four years after (2017) the compaction event.Nine years after compaction, there was still a marked negative effect of compaction on the soil structure assessed by the SubVESS method, with the largest impact observed on soil strength, root growth restriction, and aggregate friability. Saturated hydraulic conductivity was 63% lower in the compacted treatments compared to the control, while penetration resistance increased from 1.91 to 2.65 MPa after compaction. We also observed a strong negative effect of compaction on soil air permeability (−54%), gas diffusion (−30%) and the effective air-filled porosity (−24%). These changes were reflected in decreased pore organization [PO] and tortuosity in the compacted plots. Compared to five years earlier, there was a potential for natural recovery of the gas transport and pore structure variables (ka, Dp/Do, ε, PO). In 2017, there was an average compaction-induced reduction of 55% in the mentioned variables, and this changed to 38% in 2022, suggesting an increased recovery with time. Thus, although the effect of compaction on the subsoil was persistent after several years, there is a possibility that natural processes may play a significant role in recovering critical soil functions after compaction in the upper subsoil.
Adaptive river system and economy-wide planning framework for Nile water resources management
Authors: Basheer Mohammed , Nechifor Victor , Calzadilla Alvaro , Harou Julien
Published: February 2023

Climate change is projected to affect precipitation and evapotranspiration over the Nile Basin, resulting in modifications to streamflow, irrigation water demands, and evaporation from open water bodies. Future socioeconomic pathways are a key input to climate change projections as they incorporate assumptions regarding economic systems through population and economic growth and climate policies. However, there are huge hydrological and socioeconomic uncertainties and the complex interlinkages of the climate, hydrological, river, and economic systems represent a challenge for planning a resilient future. This study introduces a planning framework for designing adaptive management plans for the Nile infrastructure system. The framework combines climate change projections from CMIP6, a semi-distributed hydrological model, a river infrastructure system model, economy-wide models of Ethiopia, Sudan, and Egypt, and a multiobjective design algorithm. The framework's hydrological, river system, and economy-wide components are linked to the climate projections, ensuring coherence in socioeconomic development. The multiobjective design algorithm provides the ability to search for efficient adaptive management plans for Nile infrastructures. The adaptive planning framework was used to design efficient options for an adaptive management policy of the Grand Ethiopian Renaissance Dam (GERD), considering economy-wide and river system interests of Ethiopia, Sudan, and Egypt in 2020-2045. We compared the performance under the adaptive policy designs to the performance under a recent proposal discussed in Washington, D.C. Results show that under an example compromise solution, the mean discounted real GDP increases by 0.77, 0.67, and 0.18 billion USD in 2020-2045 for Ethiopia, Sudan, and Egypt, respectively, compared to the Washington Draft Proposal. These economic benefits are higher in extreme climate projections, with rises in discounted real GDP of up to 15.8, 6.3, and 3.0 billion USD over 2020-2045 for Ethiopia, Sudan, and Egypt, respectively.
Patagonian Ice Sheet extent as an indicator of the regional climate regime at the Last Glacial Maximum
Authors: Castillo-Llarena Andrés , Retamal-Ramirez Franco , Bernales Jorge , Jacques-Coper Martin , Rogozhina Irina
Published: February 2023

During the Last Glacial Maximum (LGM, 23 to 19 thousand years ago), the Patagonian Ice Sheet (PIS) expanded along the Andes between ~ 38 °S to 55 °S. Existing paleoclimatic and paleoglacial evidence, especially that derived from glacial landforms, seems to indicate that the timing of maximum ice sheet expansions in the Southern and Northern Hemispheres was not synchronous. Moreover, significant uncertainties still exist in the onset of regional deglaciation and its major drivers. In this context, a combination of ice sheet modelling, glacial geochronology and paleoclimate reconstructions can provide important insights into the former PIS geometry and its contribution to the sea level low during the LGM. It can also help us infer likely paleoclimate scenarios and climate models that capture regional climate responses to global change in the most realistic manner.Here we present an ensemble of numerical ice sheet simulations of the PIS at the LGM to constrain an envelope of probable atmospheric conditions derived from a range of model-based climate forcing products from the phases 3 and 4 of the Paleoclimate Modelling Intercomparison Project (PMIP). The resulting ensemble is then used as a guideline to identify sectors of the PIS where a significant disagreement between the field evidence and modelling results is obtained, highlighting a strong dependence of the PIS geometry on the uncertainties in near-surface air temperature forcing. We find that all ensemble members consistently fail to reproduce the ice sheet extent towards the northern part of Patagonia within the explored model parameter space. At the same time, the modelled PIS expands beyond its southeastern reconstructed boundary. Our analysis of the ice sheet’s mass budget seems to indicate that these discrepancies between the modelled and reconstructed PIS extents arise from poorly resolved topographic features within the global climate models and the general lack of observational data on ice thickness distribution during the LGM. We conclude that INM-CM4-8 and MPI-ESM1-2-LR produce the most realistic climate forcing across Patagonia at the LGM. It should be kept in mind that this analysis is based only on the evaluation of modelled ice sheet extents against geological evidence, as observational data on the former ice sheet thickness are still lacking. Nevertheless, our analysis suggests that the quality of the regional model-based climate reconstructions is directly linked to the horizontal resolution that must be capable of resolving topographic features of the Andes and ideally of the PIS itself.
Lessons from Red Cross Red Crescent Anticipatory Action
Authors: Tozier Arielle , Castro Jr. Eduardo , Rahaman Hafizur , Heinrich Dorothy , Clatworthy Yolanda , Mundorega Luis
Published: February 2023

The Red Cross Red Cresent is among the organizations with the longest and most extensive experience with forecast-based action. We present the findings of recently-published research based on interviews with 139 stakeholders involved in Red Cross Red Crescent (RCRC) AA programs in 18 countries. We find that the organizaitonal benefits of forecast-based ation include capacity building, more proactive operations, and expedited humanitarian response. Forecast-based action can also help to overcome common challenges in climate services by providing a framework and decision-making and resources for early action. Despite these benefits, AA practitioners struggle with challenges common to climate services, development, and humanitarian aid, including local project ownership, capacity and infrastructure, integration with existing systems, data availability, forecast uncertainty, and monitoring and evaluation. We conclude that forecast-based action systems can only be sustainble if they address these perennial challenges and focus on building capacity and ownership. Furthermore, donors can play a major role in facilitating these shifts by providing funding designed to support long-term multi-stakeholder processes.
Analysis of organic aerosol markers and chiral compounds in an ice core from the Siberian Altai using UHPLC-HRMS
Authors: Schäfer Johanna , Burgay Francois , Singer Thomas , Schwikowski Margit , Hoffmann Thorsten
Published: February 2023

The assessment of global warming and its far-reaching influences on our planet necessitates reliable and accurate climate models. For this purpose, past atmospheric conditions like aerosol composition must be studied to understand their influence on the Earth’s climate. Ice cores are valuable climate archives that preserve organic compounds from atmospheric aerosols, which can be utilized as marker species for their respective emission sources.Secondary organic aerosols (SOAs) are formed in the atmosphere by the oxidation of volatile organic compounds (VOCs), which can be either of anthropogenic or biogenic origin. The most common precursors of SOAs are monoterpenes, which are naturally emitted by vegetation in large amounts. Furthermore, organic compounds formed during biomass burning events contribute to the aerosol budget and allow the reconstruction of paleo-fire activity. Of great interest as a marker species is the anhydrosugar levoglucosan, which is formed during the combustion of cellulose. In addition to its combustion products, intact polymeric lignin, digested via alkaline oxidative degradation, can provide information about the type of vegetation which it originated from. A large variety of these markers were analyzed in an ice core extracted from the Belukha glacier located in the Altai region of Southern Siberia covering a time span of three centuries. A sample preparation method including multiple solid phase extractions and UHPLC-HRMS analysis was employed.Chiral compounds have the same molecular formula and atom connectivity but act like mirror images of each other. In most environmental studies, no distinction is made between these so-called enantiomers. However, chirality can affect chemical and physical properties and thus influence particle formation reactions in the atmosphere. The enantiomeric ratio of a chiral compound can also further elucidate possible emission sources. Here we present the first chiral analysis of monoterpene oxidation products in ice cores and thus on a long-term scale. For this purpose, a multiple heartcut two-dimensional liquid chromatography method (mLC-LC) was developed that allows the simultaneous determination of the enantiomeric ratios of the monoterpene oxidation products cis-pinic acid and cis-pinonic acid in complex ice core samples. This novel method was successfully applied to Belukha ice core samples.
Delineating the lithospheric architecture of the Rae cratons using Hf and O isotopes and trace elements in zircon
Authors: Cutts Jamie , Davis William
Published: February 2023

Characterizing the internal lithospheric architecture of Archean cratons is key to establishing the large-scale tectonic controls that contributed to their nucleation and formation and may play an important role in identifying the occurrence and distribution of mineral deposits. As many Archean cratons have experienced a polygenetic history, including multiple magmatic, metamorphic, and/or hydrothermal events, the primary architecture of cratonic crust may be reworked and obscured. The Rae craton in northern Canada, is no exception in that it grew through the accretion of Neoarchean (dominantly 2.58-2.75 Ga) crustal blocks followed by its amalgamation with the Slave, Hearne, and Superior cratons during <2.0 Ga Palaeoproterozoic orogenic events.Hafnium (Hf) and oxygen (O) isotopic analysis of zircon in crustal rocks has proven to be a powerful tool to elucidate crustal architecture by identifying spatial and/or temporal changes in isotopic composition that directly relate to distinct crustal age and compositional domains within a craton. Specifically, Hf isotopic data addresses the age (and compositions) of the source to igneous rocks, including degree of contamination of juvenile magmatism, while O isotope compositions monitor the extent of recycling of hydrothermally altered or weathered crust. However, systematic Hf and O isotopic data for different bedrock source terranes within Archean terranes of northern Canada is not widely available limiting the ability to refine lithospheric structures that may be preserved in the crustal column.In this study, we present preliminary in-situ U-Pb-Hf-O-trace element data from 115 Archean samples from across the Rae craton that were selected from the geochronology archive at the Geological Survey of Canada. All samples have been previously dated and were selected to cover the full spatial and temporal breadth of the craton with priority given to those preserving the highest quality zircon with the most unimodal age distributions. A small number of grains per sample were first dated by secondary ion mass spectrometry (SIMS) to confirm prior age determinations and to identify key grains for subsequent O and Hf isotope/trace element analysis by SIMS and laser ablation – inductively coupled plasma mass spectrometry, respectively. Collectively, these data will help refine petrological models of Rae crust formation, differentiate crustal domains that may or may not have experienced contrasting processes of formation, and contribute to identifying potential boundaries between isotopically different crustal blocks representing cryptic tectonic transitions within the cratons.
Historical and projected drought characteristics across different hydrological regimes in Central Chile
Authors: Lema Fabián , Mendoza Pablo , Vásquez Nicolás , Mizukami Naoki , Zambrano-Bigiarini Mauricio , Vargas Ximena
Published: February 2023

Drought is one of the main hydroclimatic hazards worldwide, affecting water availability, ecosystems and socioeconomic activities. Since 2010, Central Chile (30–38°S) has been experiencing a drought with unprecedented duration and severity (also known as the Central Chile megadrought), producing drastic reductions in river flows, snow cover and reservoir levels. Nevertheless, there is limited understanding of how hydrological processes have been altered and whether such variations will persist during the 21st century. In this study, we characterize the magnitude, frequency, and duration of drought events under historical conditions and future climate scenarios across different hydrological regimes in Central Chile. To this end, we generate daily time series of streamflow, evapotranspiration, soil moisture and other hydrological variables in six case study basins with little human intervention for the period 1981-2100, using the Structure for Unifying Multiple Modeling Alternatives (SUMMA) framework and the mizuRoute model. Simulations are conducted at a 0.05º x 0.05º horizontal resolution, using a combination of the CR2MET gridded product and ERA5 outputs to obtain historical meteorological forcings, and statistically downscaled global climate model (GCM) outputs from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to obtain future climate time series. Finally, we characterize drought events with the Standardized Precipitation Index (SPI), Standardized Streamflow Index (SSI), and Soil Moisture Index (SMI). The calibrated hydrologic model parameters yield daily streamflow simulations with a Kling-Gupta Efficiency (KGE) greater than 0.78 and 0.61 in all basins for the calibration and evaluation periods, respectively. The drought indices estimated for the historical period enable identifying the severe events of 1998-1999 and 2010-2020 (with standardized values smaller than -1.28); however, the magnitude and duration varies depending on the event and hydrological variable analyzed. Ongoing work seeks to examine inter-basin differences in terms of drought characteristics, along with projected changes in the frequency and intensity of this type of event.
Metamorphic evolution of the south-western Ivrea-Verbano Zone (Ivrea Town area, NW Italy): metamorphic textures, mineral assemblages and P-T evolution.
Authors: Karastergios Stylianos , Ferrando Simona , Frezzotti Maria Luce
Published: February 2023

In the Italian Alps, the Ivrea-Verbano Zone (IVZ) is known as one of the best preserved, i.e., not re-equilibrated during Alpine metamorphism, Variscan Units and, from SW to NE, it extends from Ivrea to Locarno. The sub-units constituting the IVZ are the Kinzigite Formation (supracrustal metapelites intercalated with marbles and metamafic rocks), the Peridotitic Massifs (Baldissero, Balmuccia and Finero) and the gabbroic Mafic Complex. The well-studied lithologies from Val Strona di Omegna and Val Sesia provide evidence of a nearly completed section from the lower crust (e.g., mafic granulites, metamafic migmatites, migmatitic metapelites) to the middle crust (e.g., amphibolites, marbles, calc-silicates and minor quartzites). In the present work, we focus on the less-studied area around Ivrea town to provide further insights into the P-T-X evolution of the IVZ.Our field work shows that the main attribute of the Ivrea outcrops is the presence of metamafic rocks intercalated with enderbitic granulites and minor high-grade metapelites (stronalites). The lithologies and their field relationships are compatible with the metamafic septa intercalated with migmatitic meta-sediments of pelitic to psammitic composition and calc-silicates of the Kinzigite Formation described in the Val Strona di Omegna and Val Sesia areas.The metabasites (orthopyroxene + clinopyroxene + plagioclase + amphibole + spinel + magnetite + ilmenite) are two-pyroxene granulites devoid of garnet. They are characterized by the widespread presence of brown amphibole, whose volume may locally exceed 20% of the rock (point-counting data). The enderbitic granulites consist of orthopyroxene + plagioclase + ilmenite + magnetite, relict calcic plagioclase + K-feldspar ± quartz, and minor retrograde amphibole and biotite. The stronalites are metapelites consisting of garnet + plagioclase + sillimanite + quartz + rutile + relict biotite. Despite the very simple mineralogy, more than one generations of the same mineral assemblage have been identified in the studied rocks by both textural relationships and mineral chemistry. These data suggest a complex metamorphic evolution of the studied area.Preliminary P-T estimates (winTWQ software) have been obtained for each mineral assemblage of the two-pyroxene granulites. The results suggest a prograde-to-peak evolution under amphibolite- to granulite-facies conditions. Pressure is not higher than 5,5 – 6,5 kbar, in agreement with the absence of garnet. The temperature varies depending on the considered mineral assemblage.Our data suggest that the Ivrea area belongs to the Kinzigite Formation and corresponds to a lower crust at the transition with a middle crust. The peculiar presence of the enderbitic granulites suggests a more complex evolution of this area with respect to the Val Strona di Omegna and Val Sesia areas.
Repurposing of idle wells from the oil and gas industry into deep borehole heat exchangers
Authors: Koltzer Nora , Schoenherr Johannes , Sporleder Maximilian , Steininger Sebastian Andreas , Halm Marcel , Kettermann Michael , Wellmann Florian
Published: February 2023

The motivation behind this study is to repurpose idle wells from hydrocarbon exploration and production to provide heat for end users being located near the idle well. This is possible by prolonging the value-added chain of idle wells from the gas and oil industry by re-completion as geothermal closed loop wells. This is the most efficient way to produce green energy without drilling new wells by saving the carbon emission and costs of building a new geothermal well.With this feasibility study we quantify the concept of re-completing idle wells in the North German Basin (NGB) into deep coaxial borehole heat exchangers. With numerical models of two typical geological settings of the NGB and two different completion schemes it was possible to simulate the thermal performance over a lifetime of 30 years. The calculated heat extraction rates are in the range of 200 kW to 400 kW with maximum values of up to 600 kW. This is higher than from already installed deep borehole heat exchangers. Sensitivity analyses demonstrate that flow rate, injection temperature and the final depths of re-completion are the most impacting parameters of thermal output determination.In the final project stage, the heat demand around two exemplary boreholes was mapped and possible heating networks were simulated. The initial production costs for heat are comparable to other renewable energy resources like biomass and - depending on distance between source and user – well competitive against current gas prices. These calculations highlight not only the environmental valuable motivation behind the concept of repurposing idle wells but could also save capital expenditures for the geothermal industry.Using a vacuum isolated tubing characterized by very low thermal conductivity of 0.02 W/(m*K), would make it possible to use the geothermal resources even more efficiently from idle wells. This project highlights the major potential of usable geothermal resources in already installed deep wells. The application has almost no geological risk, as the concept is independent of reservoir uncertainties like permeability and reservoir fluid composition, drilling risks are skipped completely and it is realizable at any location.
Identifying a seasonally inundated, nutrient-poor peat swamp forest type in the central Congo Basin
Authors: Crezee Bart , Dargie Greta , Ewango Corneille , Baker Timothy , Bola Pierre , Emba Ovide , Girkin Nicholas , Kanyama Joseph , Ndjango Jean-Bosco , Lewis Simon
Published: February 2023

The Cuvette Centrale wetland area in the central Congo Basin is home to the most extensive peatland complex in the tropics, which covers an estimated 167,600 km2 and stores approximately 29.0 petagrams of carbon belowground (Crezee et al., 2022). However, relatively little is known about these peat swamp forests, which span both the Republic of the Congo (ROC) and the Democratic Republic of the Congo (DRC). In ROC, peatlands are mostly found in interfluvial basins, where they form wide but shallow peat domes (Davenport et al., 2020), which are largely rain-fed, have ombrotrophic (low-nutrient) status and are covered by distinct hardwood- or palm-dominated forest vegetation types (Dargie et al., 2017). In contrast, peatlands in DRC can be found in different hydro-geomorphological settings, including relatively narrow river valleys along the Congo River’s eastern tributaries.Here, we present insights from in situ measurements of water table depths, peat and water chemistry, and vegetation characteristics along three of these tributaries, the Ruki, Busira and Ikelemba Rivers. Peat deposits (≥ 30 cm of ≥ 65% organic matter) were found in seasonally inundated swamp forests close to rivers, which are characterised by large (>1 m) wet season inundations. This shows that peat formation in the central Congo Basin is not only confined to permanently waterlogged swamps with relatively stable water tables year-round, predominating in ROC’s interfluvial basins, but also occurs in swamp forests that experience greater water table seasonality. Seasonal inundations are due to riverbank overflow during the wet season, and potentially upland runoff from higher terra firme ground. Since the Congo River’s eastern tributaries are highly acidic (blackwater) rivers, the seasonally inundated, river-fed swamps are still of low nutrient status, allowing peat to form. Nonetheless, they are typically characterised by shallower peat deposits than permanently waterlogged swamp forests. Comparison of vegetation plot data identifies a distinct forest type in the seasonally inundated, river-fed peat swamps: a hardwood swamp forest dominated by Oubanguia africana and Guibourtia demeusei. This vegetation type was previously described by Evrard (1968), but was not known to overlie peat soils.Our findings identify distinct rain-fed and river-fed peatlands in the central Congo Basin. These two peatland types may face different threats to their integrity. While rain-fed peatlands will be susceptible to future climate change if rainfall levels decrease, those that are also maintained by riverbank overflow, may be susceptible to changes in upstream rainfall patterns. This, as well as infrastructure projects that affect river dynamics, will likely have larger impacts on peatland functioning than previously thought.
Wind forcing and tides mediate transport of ocean heat from Storfjordrenna to the Arctic domain of the Barents Sea
Authors: Kalhagen Kjersti , Skogseth Ragnheid , Fer Ilker , Baumann Till M. , Falck Eva
Published: February 2023

The Barents Sea is undergoing changes with impacts on the physical environment, e.g., the seasonal sea ice formation and extent and with large consequences for the ecosystems. There are knowledge-gaps concerning the complex pathways of Atlantic Water (AW) through the Barents Sea and the associated distribution of heat and nutrients. Records from a mooring deployed between September 2018 and November 2019 on the 70 m deep saddle between Edgeøya and Hopen islands in the Svalbard archipelago show sporadic exchange between the AW-influenced trough Storfjordrenna and the Arctic domain of the north-western Barents Sea. Forced by sea surface anomalies, the observed currents show a tendency for eastward transport across the saddle year-round. However, the eastward overflow into the Barents Sea is strongly mediated by wind forcing: The predominant north-northeasterly winds with corresponding geostrophic adjustment to Ekman transport tend to hamper and sometimes even reverse this cross-saddle current. Weaker and/or southerly winds on the other hand tend to enhance the eastward flow into the Barents Sea. The strength and shape of the overflow current vary substantially on seasonal and sub-seasonal timescales: during autumn and winter, the current is strong and barotropic, while during summer, the current is weaker and more baroclinic. On shorter time scales, the strongest oscillations occur during the ice-free autumn with a periodicity of a few days. When the area has a partial sea ice cover in winter, the strength decreases and the periodicity increases to a week or more. Further analysis of variability in temperature and current velocity shows that cross-saddle transport of positive temperature anomalies (indicating heat from waters of Atlantic origin) is evident in frequency bands associated with various drivers of mesoscale variability, such as eddies, synoptic events, and tides. There are indications that the studied area will become an increasingly important location for heat transport into the interior of the Barents Sea: A comparison between historical and recent hydrographic records show that AW is warming and shoaling in the water column in Storfjordrenna, which suggests that AW will be more easily transported across the saddle by the mentioned drivers. Furthermore, the ongoing changes in the large-scale weather patterns resulting in more southerly and southwesterly winds is hypothesized to affect the strength and persistence of the overflow on the saddle between Edgeøya and Hopen islands.
Generation of multi-resolution, daily and gap-free ocean colour satellite products for coastal applications: the MultiRes project
Authors: Alvera-Azcárate Aida , Barth Alexander , Dille Antoine , Van der Zande Dimitry
Published: February 2023

Coastal ocean areas are very dynamic regions subject to strong anthropogenic pressure (e.g. industry, tourism, renewable energies, population). Satellite data constitute a unique tool to study and monitor these complex areas at high spatial and temporal resolutions. While “traditional” ocean colour satellites like Sentinel-3 provide daily temporal resolution, their sensors do not measure at the spatial resolution needed to correctly resolve complex coastal dynamics. On the other hand, while high spatial resolution sensors, like the MSI onboard Sentinel-2 (10m - 60m resolution), are able to resolve these small scales, their revisit time is far from optimal (2-5 days for the Sentinel-2 A & B tandem). Additionally, both high spatial resolution datasets and traditional ones are hindered by the presence of clouds, resulting in a large amount of missing data. Given the high complementarity of these two measurement strategies (Sentinel-3 and Sentinel-2), we present a methodology to derive gap-filled multi resolution ocean colour products from the synergistic use of Sentinel-2 and Sentinel-3 data. Applying DINEOF (Data Interpolating Empirical Orthogonal Functions), we exploit and combine both the high-resolution spatial variability information contained in Sentinel-2 products as well as the high temporal information of Sentinel-3. Both Sentinel-2 and Sentinel-3 products are generated using the Copernicus Marine High-Resolution processor, which uses automated switching algorithms adapted to the local water conditions (at the pixel level) to retrieve optimal remote sensing spectra and water quality variables. With this approach, we address the high variability of different water types with small scale changes. The combined Sentinel-2 and Sentinel-3 products consist of Chlorophyll-a concentration and turbidity retrieved through a multi-algorithm approach with optimized quality flagging. An analysis of turbidity and chlorophyll daily data at 100m resolution in the northern Adriatic Sea and the Belgian coastal zone will be presented, alongside an analysis of the spatial scales resolved by the original and merged DINEOF datasets.
The usage of fog and dew in solar power plants of the Atacama Desert
Authors: Lobos Roco Felipe , Suarez Francisco , Escobar Rodrigo , Osses Pablo , Ramirez Carla , Keim Klaus , Aguirre Ignacio , Aguirre Francisca , Vargas Constanza , Abarca Francisco , del Rio Camilo
Published: February 2023

The Atacama desert is one of the most promising places on Earth for developing solar power energy due to its aridity, irradiation, and market conditions. However, the high levels of dust attenuate solar power production. This problem is solved by frequent cleaning of the solar panels, which requires a significant amount of water in one of the driest places in the world. Despite the drought condition, the fog and dew formed at the coastal zone of the desert arise as a complementary water source that can potentially be tapped. In this study, we assess the potential of atmospheric water for usage in four solar power plants. We conduct this assessment by combining a satellite-spatial analysis of fog and low cloud frequency, a thermodynamic vertical characterization of the marine boundary layer, and an observational analysis of fog and dew collection using different instruments. Our results reveal that fog and dew are a regular phenomenon in the solar power plants analyzed, being present between 3% and 20% of the year. Oceanic conditions control such phenomena through the inland advection of the marine boundary layer. This layer interacts with a complex topography characterized by natural corridors that allow fog and low clouds to penetrate farther inland. Our observations show that fog and dew are collected mainly during the night, with average rates between 0.1 and 0.2 L m-2 day-1. Our research confirms that atmospheric water potential vastly exceeds the solar power plant water demand, demonstrating that atmospheric water is a reliable source for the industry.