bluuebunny/crossref_metadata_2025 huggingface dataset:
Synergistic Effects of Raised Temperature and CO2 on Strategists of Soil Enzyme and Microbial Communities
Authors: Song Bin , Yu Zhenhua , Wang Yuchao , Adams Jonathan , Razavi Bahar
Published: March 2024

The effects of global warming and CO2 influence on soil processes and crop growth are a major area of concern. Rhizosphere soil enzymes, mostly produced by microbes, play a pivotal role in enhancing soil nutrient accessibility for plant assimilation. Knowledge about the responses and adaptations related to the nutrient acquisition in space of microbial communities to increased temperature and CO2 re remaining deficient. Here, we grew soybean in rhizobox mesocosms under raised temperature (+2 ℃, ET) and CO2 (+300 ppm, ECO2) and the combination (ECO2+ ET). ECO2 increased the enzymatic hotspot area from 1.8 to 3.3% of soil, while ET increased enzyme activities by 2.5%-8.7%. Notably, the combined influence of ECO2 and ET synergistically amplified both the scope (increasing by 5.3% to 10.1%) and intensity (escalating by 35.4% to 67.3%) of three concurrent enzymes. Compared to ambient, rhizosphere communities in ECO2 were dominated by the keystone taxa of r-strategists, Acidobacteria, Proteobacteria, and Ascomycota. Conversely, ET shifted the microbial community to K- selection by increasing the relative abundance of Basidiomycota and Actinobacteria. Meanwhile, ECO2+ ET promoted the relative abundance of bacterial keystone species (Acidobacteria, Proteobacteria, and Actinobacteria) and fungi (Ascomycota and Basidiomycota) of the total community. These observations emphasize the potentially key role of enzyme hotspot areas in mediating climate change responses. Changes in the activity and extent of enzymes observed under the experimental treatments suggest a shift in balance towards a mixed r and K strategy in the hotspot microbiota. The microbial communities showed clear shifts in composition of the structure in response to the treatments, with changes in taxonomic composition, network structuring, and the balance between r and K-designated species.
Satellite-Driven Traffic Volume Estimation: Harnessing Hybrid Machine Learning for Sustainable Urban Planning and Pollution Control
Authors: Aslam Bilal , Hocking Toby , Dass Pawlok , Kato Anna , Gurney Kevin
Published: March 2024

As cities grow and more cars occupying the roads, greenhouse gas emissions and air pollution in urban areas are going up. To better understand the emissions and pollutions, and help effective urban environmental mitigation, an accurate estimation of traffic volume is crucial. This study delves into the application of Hybrid Machine Learning models to estimate and predict traffic volume by utilizing satellite data and other datasets in both the USA and Europe. The research investigates the predictive capabilities of machine learning models employing freely accessible global datasets, including Sentinel 2, Night-time light data, population, and road density. Neural Network, nearest neighbours, random forest and XGBoost regression models were employed for traffic volume prediction, and their accuracy was enhanced using a hyperparameter-tuned K-Fold Cross-validation technique. Model accuracy, evaluated through Mean Percentage Error (MPE%) and R-square, revealed that XGBoost Regression model yielding an R2 accuracy of 0.81 and MPE of 13%. The low error (and therefore high accuracy) as well as the model's versatility allows its application worldwide for traffic volume computation utilizing readily available datasets. Machine learning models, particularly the XGBoost Regression model, prove valuable for on-road traffic volume prediction, offering a dataset applicable to town planning, urban transportation, and combating urban air pollution.
How does tropical Atlantic Multidecadal Variability develop?
Authors: Senapati Balaji , O’Reilly Christopher H. , Robson Jon
Published: March 2024

Atlantic Multidecadal Variability (AMV) has been linked to climate variability in many regions across the globe. However, the mechanisms through which the AMV develops remain unclear. Modelling studies show that global teleconnections from the AMV are sensitive to how the tropical branch is represented, though understanding how the decadal Sea Surface Temperature (SST) anomalies develop in this region has received little attention. Here, we present a quantitative examination of the generation of tropical AMV using SST restoring experiments. In contrast to the generally proposed mechanisms of wind-flux-SST or cloud feedback, this study provides new insight into the dominance and crucial role of upper ocean dynamics, particularly concerning the mixed layer depth. Given the sensitivity of tropical AMV on global implications, the accurate simulation of the upper ocean dynamics in coupled climate models becomes imperative.
Dependence of simulated variability of surface climate on model complexity – insights from an ensemble of transient simulations of the Last Deglaciation
Authors: Ziegler Elisa , Weitzel Nils , Baudouin Jean-Philippe , Kapsch Marie-Luise , Mikolajewicz Uwe , Gregoire Lauren , Ivanovic Ruza , Valdes Paul , Wirths Christian , Rehfeld Kira
Published: March 2024

Climate variability is crucial to our understanding of future climate change and its impacts on societies and the natural world. However, the climate records of the observational era are too short to explore long-term variability. Conversely, an exploration of long transient simulations from state-of-the-art Earth System Models (ESMs) poses high computational demands. It is therefore pertinent to identify the level of complexity sufficient to simulate the variability of surface climate from annual to centennial and longer timescales.To this end, we use an ensemble of transient simulations of the Last Deglaciation, the last period of significant global warming. The ensemble covers an energy balance model (EBM), models of intermediate complexity (EMICs), general circulation models (GCMs) and ESMs. This constitutes a hierarchy that we categorize based on employed atmosphere and ocean components and their resolution, as well as implemented radiation, land hydrology, vegetation and aerosol schemes.To investigate the simulated variability of surface temperature and precipitation, we analyze changes in the shapes of their distributions as characterized by their higher order moments – variance, skewness, kurtosis – with warming. These higher order moments relate the tails to the extremes of the distributions. We identify spatial and temporal patterns and how they depend on model complexity. The EMICs can generally match the global and latitudinal changes in temperature variability found in more complex models. However, they lack in precipitation variability. We further find that the EMICs fail to simulate the tails of the precipitation distributions. We observe dependency of variability on the background state, generally increasing with model complexity. However, there is still a large spread between models of similar complexity, some of which can be related to differences in forcings. Furthermore, questions remain on the abilities of models of any complexity to simulate a magnitude of long-term variability similar to that found regionally in proxy reconstructions. Our analysis offers implications as to the complexity needed and sufficient for capturing the full picture of climate change and we offer some first insights into how the findings translate to future projections of climate change.
Atmospheric Impacts of Hydrogen as a Sustainable Aviation Fuel
Authors: Gibney Evan , Eastham Sebastian , Allroggen Florian , Barrett Steven
Published: March 2024

Hydrogen is being investigated as a promising zero-carbon sustainable aviation fuel (SAF), offering the potential to eliminate direct CO2 emissions with low lifecycle greenhouse gas emissions. Additionally, the combustion of hydrogen can remove all emissions of SOx, nvPM, CO, and unburned hydrocarbons. There are, however, climate and air quality costs to the use of hydrogen. Combustion of hydrogen is still expected to result in emissions of NOx, and the degree to which contrails will be increased or mitigated is unknown. In addition, there has been little research into the long-term consequences of direct emission of hydrogen.Hydrogen emissions originate from leakage, venting, and purging that occur both within the supply chain and on the aircraft. Though not a direct greenhouse gas, hydrogen reacts in the atmosphere via mechanisms that increase the effects of other potent greenhouse gases and air pollutants. Specifically, increased emissions of hydrogen are projected to increase the lifetime of methane, the tropospheric burden of ozone, and the stratospheric burden of water vapor – all greenhouse gases. No study to date has assessed the additional climate impacts associated with direct emission when considering hydrogen as an aviation fuel. Furthermore, with the dominant loss mechanism of emitted hydrogen being based in soil, no study has evaluated the degree to which these indirect mechanisms might differ for hydrogen which is emitted at altitude. These considerations have the potential to change the perceived sustainability of hydrogen as an aviation fuel.In this study, we quantify the climate and air quality impacts (excluding contrails) of a hypothetical future hydrogen aircraft fleet compared to equivalent kerosene and hydrocarbon-based SAF fleets. We use the GEOS-Chem global chemistry transport model, modified to represent hydrogen’s surface soil sink, to conduct a spatially discretized, multi-year impact assessment. Multiple scenarios are evaluated to address uncertainty in factors such as hydrogen leakage rates and NOx emissions from hydrogen aircraft. This assessment will provide the foundation for understanding the magnitude of the environmental benefits and costs of hydrogen-fueled aviation.
CESM2energy: a modular climate-to-energy pipeline 
Authors: Bloin-Wibe Luna , Göke Leonard , Savelsberg Jonas , Wohland Jan
Published: March 2024

Transitioning to renewable energy will be instrumental in mitigating the devastating effects of climate change. Because of the many unknowns in the design and dispatch of future energy systems, quantifying climate risk in the energy sector is challenging: in particular, renewable energy production and heating demand is highly reliant on meteorological conditions, which are variable in nature and shifting due to climate change.It is therefore important to use large samples of renewable generation and demand, for current and future climates, in energy system modeling. However, lacking standardized ways to translate between the climate and energy model world, most existing studies rely on different assumptions and draw from a limited sample of available climate variables.To this end, we created a modular climate-to-energy pipeline: starting with hourly output from the climate model CESM2, it bias corrects, translates, and scales to the various inputs of energy system models. We base the conversion on open-source tools: GSEE for solar power generation, windpowerlib for wind from climate model levels and demand.ninja for heating and cooling demand. The resulting pipeline ensures consistency of variables, with inputs and outputs tailorable to specific needs.We use the pipeline to analyze seasonal cycles of energy generation and demand under different weather conditions, for current and future climates deploying the AnyMOD.jl framework for energy system modeling. Because of the modular approach, the pipeline could easily be adapted for other climate models and time-series, providing better evidence for climate-informed energy system planning.
Benthic foraminifera in the surface sediments of the southern Baltic Sea – paleoenvironmental proxy perspectives
Authors: Jernas Patrycja
Published: March 2024

The Baltic Sea developed to its modern settings as a result of complex processes initiated by the retreat of the Fennoscandian Ice Sheet around 15,000 cal BP. The formation of the Baltic Sea went through a series of stages, each of which was characterized by changes in environmental conditions, especially in terms of spatial extent, salinity and water levels. Although the history of sea level and salinity changes in the Baltic Sea has already been fairly well described, different parts of the current basin have been subjected to changes of varying speed, extent and consistency with the general trend for the entire Baltic, as exemplified by foraminifera based reconstructions from more saline western region of the sea.The aim of the study, was to investigate whether foraminifera could also inhabit the low saline southern Baltic Sea and whether there would be indicator species among them, preferring e.g. a certain ranges of temperature or salinity of the bottom water. For this purpose, surface sediments were examined from 19 locations following the salinity gradient, from the more saline Bornholm Basin to areas characterized by gradual water freshening, i.e. the Slupsk Furrow, the Gdansk Basin, up to the Gotland Basin. The obtained results indicate that the foraminifera biodiversity is low (5 species), which is common in the low saline environment of the Baltic Sea. The foraminifera fauna showed pattern in species distribution from the western to the eastern part of the studied transect. The muddy sediments of the Bornholm Basin (bottom salinity of 16.58) were rich in Ammonia beccari, Elphiudium excavatum clavatum and Elphidium incertum. The sandy-gravel sediments of the Slupsk Furrow were barren or single individuals of Miliammina fusca occurred randomly, which may be related to the strong hydrodynamics of the bottom currents at this area. The Gdansk Basin up to the Gotland Basin (bottom salinity around 12) was dominated by Reophax dentaliniformis, which also accounted for more than 70% of the total foraminifera fauna of the southern Baltic Sea in terms of abundance. The conducted statistical analysis indicates a strong correlation of A. beccari and Elphidium spp. with temperature and salinity of the bottom waters, whereas R. dentaliniformis with sea depth, the knowledge that can be used in palaeoceanographic reconstructions of the Baltic Sea.
Reflections regarding our biogeochemical studies in lakes and marine environments
Authors: Conley Daniel
Published: March 2024

My fascination with the biogeosciences started with the investigation of nitrogen (N) and phosphorus (P) enrichment of lakes stimulating the growth of diatoms leading to increased sedimentation and eventual depletion of dissolved silicate from the water column. At that time most research on the global Si cycle was focused on weathering and had not explored the complexity of the terrestrial biogeochemical cycle. Our research demonstrated that diatoms and phytoliths, e.g. biogenic silica that accumulates in the living tissues of growing plants, are transported from lakes and rivers on the continents into the oceans. The emerging understanding is that the flux and isotopic composition of dissolved silicate delivered to the ocean has likely varied over time mediated by a fluctuating continental pool. An important question we addressed was if reductions of P and N could reduce eutrophication and degradation of freshwater and marine ecosystems. Our analysis explored the rationale for only P or only N reductions and concluded that dual–nutrient reduction strategies were needed for aquatic ecosystems. A focus on only P or only N reduction should not be considered unless there is clear evidence or strong reasoning that reducing the inputs of only one nutrient is justified in that ecosystem and will not harm downstream ecosystems. The depletion of dissolved oxygen in bottom waters is one of the common responses of aquatic ecosystems to eutrophication. A classic example is the semi-enclosed brackish Baltic Sea. Our research has shown that the Baltic Sea is the largest anthropogenically induced hypoxic area in the world, which has increased 10-fold during the last century due to increased nutrient inputs. Concurrently, the coastal zone has experienced increasing hypoxia during the same period with the Baltic Sea coastal zone containing over 20% of all known sites suffering from hypoxia worldwide. Our research has highlighted the continuously growing problems of hypoxia and anoxia with eutrophication. Altered global biogeochemical cycles is not only a feature of the Anthropocene but ongoing geological processes. Our recent research has focused on the use of silicon isotope signatures of unaltered sponges and radiolarians to estimate dissolved silicate drawdown as a proxy for the changes in the productivity of diatom communities in the Mesozoic oceans and how the ocean chemistry changed with the evolution of diatoms. Our major results to date suggest that dissolved silicate has been low in the oceans for at least the last 100 million years because of the extreme efficiency of dissolved silicate uptake by diatoms reducing ocean concentrations. My continued enchantment with biogeochemical processes and collaboration with other creative scientists has lead to uncovering new biogeochemical pathways which stimulates the drive to learn more about how ecosystems operate.
Examination of the organic carbon stock of the soil of Hungarian beech stands and the determining factors
Authors: Bidló András , Balázs Pál , Katona Máté , Végh Péter , Horváth Adrienn
Published: March 2024

The beech stands ratio of Hungarian forests barely reaches 6%. However, beech is a native tree species with high production capacity; therefore, its importance in nature conservation and economy is significant. Due to global climate change, the focus is on the ability of carbon fixing and storage capacity in beech forest ecosystems. While we can estimate the amount of biomass above ground with relative precision, we have little data about organic carbon in soils.The primary goal of our work was to collect as much data as possible on the amount of organic carbon stored in the soil of these native forest stands. Furthermore, the most significant factors were determined that influenced the sequestration.During the research, undisturbed and disturbed soil samples were collected from every 10 cm layer in 40 beech stands. The depth depended on the bedrock. On loessy or sandy bedrock, the depth was 110 cm. In the case of rocky structure, samples were taken from 0-40 cm depth. Moreover, litter samples were taken and analyzed. The properties of the stands were also recorded on the sampling sites (tree species, diameter, etc.).The soil pH was 5.17 on average, while the minimum value was 3.87 and the maximum was 8.4. The humus content varied between 0.16 and 15.65% because it decreased with depth. The average organic carbon stock was 6.39 C t/ha (Cminimum  1.46 C t/ha, Cmaximum 34.03 C t/ha). Moisture determines the organic carbon stock of the soil most of all.This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme. Some of the tools used during the research were acquired within the framework of the "Investigation of the conditions for the cultivation of wood biomass - GINOP-2.3.3-15-2016-00039" project.
Fingerprinting the AMOC and predicting a collapse
Authors: Ditlevsen Peter
Published: March 2024

 In a recent paper [2] we predicted a collapse of the AMOC as soon as mid-century at odds with assessments based on climate model scenarios. The prediction was based on the sub polar gyre fingerprint as a proxy for the AMOC as proposed by Ceasar et al. [2]. Several other fingerprints have been proposed, all showing early warning signals of a forthcoming tipping point [3]. Here we present a statistical analysis, optimally extracting the common signal in the different fingerprints in order to further solidify the assessments. [1] Ditlevsen, P., Ditlevsen, S. Warning of a forthcoming collapse of the Atlantic meridional overturning circulation. Nat Commun 14, 4254 (2023)[2] Caesar, L., Rahmstorf, S., Robinson, A. et al. Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature 556, 191–196 (2018)[3] Boers, N. Observation-based early-warning signals for a collapse of the Atlantic Meridional Overturning Circulation. Nat. Clim. Chang. 11, 680–688 (2021)
Fault (re)activation and fluid-induced seismicity: an example from the Val d'Agri intermontane basin (southern Italy)
Authors: Lavecchia Alessio , Serlenga Vincenzo , Filippucci Marilena , Stabile Tony Alfredo , Prosser Giacomo , Tallarico Andrea
Published: March 2024

The occurrence of fluid-induced, moderate-to-large earthquakes in several locations around the globe sparked interest in the relationships between fluids and seismicity over the last few years. Several studies suggest variations of the stress state of rocks, due to the increase or drop of the pore fluid pressure, can be a mechanism that can trigger earthquakes in the presence of fluid phases. In this scenario, the Val d’Agri represents a precious case study where the effect of fluids on seismic activity can be observed. In this region, wastewater reinjection reactivated the Costa Molina blind thrust in the eastern sector of the Val d’Agri, where present-day seismicity was almost absent. A few kilometers SW from this cluster, seasonal water loading from the artificial Pertusillo reservoir generates further seismic activity within the buried carbonatic platform. The formation and evolution of the faults generating seismicity are still a matter of debate, especially in the compressional/extensional tectonic setting that characterizes the southern Apennines geological history. Consequently, the distribution of the seismic potential in the region is largely unconstrained.We built up a numerical, thermo-mechanical model to identify the principal mechanisms that generated the present-day tectonic setting observed in the Val d’Agri and the surrounding region, and to assess the seismic hazard characterizing this area. We suggest the presence of a major dècollement layer that decouples deformation between the sedimentary cover and the crystalline basement, represented by the Triassic Burano Formation. Our model quantifies the stress field and estimates Coulomb stress values in the Val d’Agri crust, allowing us to assess the potential of the rocks to generate earthquakes. We suggest that Coulomb stress values are positive in a large part of the crust, and therefore that fluid injection may be particularly effective for the reactivation of buried structures, especially within the carbonatic platform at a depth between 2 and 6 km.
The enigmatic Mount Grace extrusive carbonatites, southeastern Canadian Cordillera: volcanic architecture, mantle source, and tectonomagmatic framework
Authors: Abdale Lindsey , Groat Lee , Russell J. Kelly , Millonig Leo
Published: March 2024

The Late Devonian Mount Grace carbonatites outcrop as thin, laterally discontinuous strata-bound lenses within the deformed and metamorphosed Monashee cover sequence of the Canadian Cordillera. The identified lithofacies range from carbonatite tuffs to tuff breccias, in line with a pyroclastic origin resulting from phreatomagmatic eruptions forming in a field of maar volcanoes. Carbonatitic eruptions occurred in a transgressive shallow marine platform setting along the western margin of paleo-North America. The timing and distribution of the Mount Grace carbonatites correlate with regional Late-Devonian back-arc extension and other rift-related sedimentary exhalative deposits, alkalic volcanism, and carbonatite and alkalic intrusions. Whole-rock geochemistry of the Mount Grace carbonatites shows a strong positive Nb anomaly, moderate REE contents with high LREE/HREE, and strongly negative Zr-Hf anomalies that overlap with global rift-related carbonatite compositions. A positive correlation exists between REE content and LREE/HREE, and Nb/Ta and Zr/Hf in Mount Grace samples that indicate primary carbonate and pyrochlore crystallization, increasing in the more evolved compositions. The evolved compositions correspond with higher proportions of phoscorite (apatite, biotite, ferrorichterite, and pyrochlore). We invoke an ascent model for the Mount Grace carbonatites, similar to other carbonatite/phoscorite complexes where an ascending parental carbonate-phosphate/Fe oxide-rich melt undergoes liquid immiscibility of phoscorite-enriched carbonatitic magma, allowing the lower density residual phoscorite-poor carbonatite magma to ascend rapidly through the crust. Zircon Hf and apatite and pyrochlore Nd and Sr isotopes from the Mount Grace carbonatites have relatively depleted mantle signatures at 360 Ma, very close to Focal Zone (FOZO) and high mu (238U/204Pb; HIMU)-like mantle reservoir endmembers similar to global ocean island basalts and indicates a mantle source for these melts, potentially of great depths. Apatite and pyrochlore Nd and Sr isotopes from the Mount Grace carbonatites fall within the range of values for a depleted mantle reservoir presumably developed at ~3 Ga that sits beneath the Canadian Cordillera based on data from carbonatites emplaced from 2700 to 110 Ma in the Cordillera and Canadian Shield. Zircon Hf from Mount Grace carbonatites overlap with this depleted FOZO-HIMU mantle endmember and extend towards more enriched Hf values, reflecting their metasomatic origins. We infer that reactivated crustal-scale rifts allowed the emplacement of small-degree partial melts of an underlying, moderately depleted mantle source.
Learning from the past to prepare for the worst. Impact Chain on the multi-hazard of COVID-19 pandemic and a powerful earthquake in Bucharest
Authors: Savu Cristina , Albulescu Andra-Cosmina , Armaș Iuliana , Toma-Dănăilă Dragos
Published: March 2024

In the last years, the impacts of natural hazards have been coupled with and sometimes overshadowed by those of the COVID-19 pandemic. Such co-occurrences added extra layers to risk management and highlighted the need for updated multi-hazard risk models and management plans. While developing the tools, models, and strategies to battle the challenges of the post-pandemic world, an unsettling question lingers: What if the most impactful and feared hazard in a specific area were to occur during a pandemic wave?This study aims to 1) take an in-depth look at the impact of the COVID-19 pandemic on the hospital system in Bucharest, Romania, and 2) identify the compounded impacts of a powerful earthquake that would potentially affect the city during a pandemic wave, under an Impact Chain-based approach. To this end, two Impact Chains are analysed side by side: one of them presents the actual impacts of the pandemic documented for 2020-2022, and the other focuses on the potential impacts of a powerful earthquake, similar to the one that affected Romania in March 1977 (7.4 MW). The co-occurrence of such powerful hazardous events poses a worst-case scenario for Bucharest, which stands out as the European capital with the highest seismic risk and one of the urban centres severely affected by the COVID-19 pandemic. The Impact Chain centred on the COVID-19 pandemic dwells on a wide range of sources: scientific literature, data collected from hospital administration (e.g., reports on available medical resources, including human resources), official reports from international health care organisms, legislative documents that regulate COVID-19 prevention protocols, official press releases, and grey literature in the form of news reports. The earthquake-based Impact Chain represents a simplified, expert knowledge-based version of a larger chain developed within the Paratus Project as part of the analysis of present and future outcomes of a major earthquake in Bucharest. By juxtaposing the two Impact Chains, this study addresses the research gap concerning the compounded impacts of earthquakes and the COVID-19 pandemic, an area currently open for further investigation. This analysis offers an initial answer to the worrisome question posed earlier, aiding in the preparation for “the worst” in Bucharest.Keywords: COVID-19 pandemic, earthquake, impact chain, hospital system, Romania
Managing Urban Water Supplies under Future Uncertainties: A Case Study of Bengaluru, India
Authors: Mohapatra Snigdha Sarita , Arora Meenakshi , Wu Wenyan , Tiwari Manoj Kumar
Published: March 2024

The future uncertainties, spanning both climatic (e.g., precipitation) and non-climatic (e.g., population growth) factors, will significantly impact urban water demands and supplies. To enhance future water security in urban areas, the Integrated Urban Water Management (IUWM) approach has gained popularity globally. The IUWM approach emphasizes a varied water supply source, addresses multiple sustainability objectives, and ensures the provision of fit-for-purpose water. This study uses an Integrated Urban Water Balance Model (IUWBM), developed in eWater Source platform version 5.10.0.11841, which utilizes different types of water (i.e., river water, groundwater, harvested stormwater, rooftop rainwater, and recycled wastewater) to meet future water needs. However, depending on how much water each source supplies, combining different water sources to meet the demand may result in trade-offs with the integrated urban water system's total cost and energy consumption. Given the future uncertainties, it is crucial to develop robust optimal water mix solutions that are minimal in total costs and total energy consumption across various future scenarios. This study proposes to address this challenge, focusing on Bengaluru (i.e., a city in India) as a case study due to its relevance to the identified issues. The IUWBM is linked to an optimization tool (i.e., Insight Version 5.10.0.11841, which uses the NSGA-II algorithm). Three robustness metrics—Laplace Principle of Insufficient Reasons, Hurwicz Optimistic-Pessimistic Rule, and Signal-to-Noise Ratio—are added to a multi-scenario, multi-objective optimization problem to make the decision-making more robust. All optimal solutions generated adhere to constraints, maintaining an average volumetric and time reliability of water supply above 99.50% for the study area. The findings reveal that low-cost optimal water mix solutions tend to exhibit higher energy consumption as they prioritize savings in the capital costs of building the new water supply infrastructure. Capital costs, therefore, significantly impact the total costs, while operating energy plays a crucial role in total energy consumption in Bengaluru urban water supplies. The present research also found that harvested stormwater and recycled wastewater emerge as potentially low-cost, low-energy, and reliable sources for potable and non-potable water, respectively, under future uncertainties. Additionally, recycled wastewater is preferable for non-potable uses as it offers the added benefit of mitigating adverse environmental impacts on Bengaluru's valleys and lakes.
Re-grazing of an alpine pasture sustains ecosystem services
Authors: Ramm Elisabeth , Andrade-Linares Diana R. , Garcia-Franco Noelia , Han Jincheng , von Heßberg Andreas , Dashpurev Batnyambuu , Jentsch Anke , Krämer Alexander , Schloter Michael , Wiesmeier Martin , Dannenmann Michael
Published: March 2024

Alpine pastures have shaped the landscapes of the European Alps for millennia. However, more and more alpine pastures have been abandoned since the 1950s, e.g., due to the work intensiveness at high altitudes. Such abandonment of alpine pastures in the long term leads to natural reforestation. And despite ample potential surface in the mountains, the pressure to provide important ecosystem services by pastures under the auspices of climate change nowadays concentrates on the lowlands, because already abandoned alpine pastures are still very rarely re-established. Meanwhile, it has been widely acknowledged that alpine pastures fulfill important provisioning, regulating, and cultural ecosystem services, with particularly cultural landscape and plant and faunistic biodiversity being at risk due to reforestation.     Cattle grazing during summer not only means a soil disturbance which can increase plant biodiversity, but also increases nutrient availability and has unclear effects on soil organic carbon and associated soil functions. However, the precise effects of grazing have only rarely been proven. To test whether the preservation of intact alpine pastures by re-introducing cattle grazing is worth supporting, it is important to evaluate the effects of re-grazing on the soil organic carbon (SOC) stocks, the soil nitrogen (N) cycling, and water contamination with nutrients.     Within the SUSALPS (Sustainable use of alpine and pre-alpine grassland soils in a changing climate) project, a typical alpine pasture in the German Alps abandoned in 1955 (Brunnenkopf, Ammergauer Alpen) is being re-grazed since 2018 with the traditional robust old cow breed “Murnau-Werdenfelser”. Here, we compared non-grazed to different grazed areas (low grazing intensity, high grazing intensity, bare soil due to trampling) after five years of experimental re-grazing. The data show a non-significant effect of grazing on N cycling, with only the bare soil area (6% of the pasture) showing increased gross N mineralization and soil nitrate concentrations. The nitrate concentration in the drainage water stayed overall very low (range 0.3–2.2 mg N L-1). What was striking, however, is a strong and statistically significant re-grazing-induced increase in the SOC stock by 11.8 t SOC ha-1 in five years although we corrected for bulk density increases.              Our results suggest that extensive grazing- and trampling-induced changes in belowground plant biomass, the soil microbiome, and overall productivity, are fostering soil functions of an alpine grassland soil. These findings are for the first time underpinning the presumed positive effects of grazed alpine pastures on soil functions with data.
Fluid-mediated forearc mantle metasomatism and its chemical feedbacks: Insights from coupled petrological and thermomechanical modelling
Authors: Ren Jun , Faccenda Manuele , Zhong Xin , Galvez Matthieu E. , Yang Jianfeng , Riel Nicolas
Published: March 2024

Fluid-mediated mantle metasomatism (FMM) and associated matter transfer is a key process for subduction zone evolution. Over the past decade, the implementation of thermodynamic modelling into geodynamic numerical models became popular, boosting dozens of new insights into ongoing processes within mantle wedge.Building on the work of Galvez et al. (2015) and Zhong and Galvez (2021), we now combine the original fluid speciation algorithm within a geodynamic model to obtain a chemo-thermo-mechanical modelling platform. It integrates a Gibbs free energy minimizer, e.g. Perple_X or MAGEMin (Connolly et al., 2005; Riel et al., 2022), the ‘single’ backcalculation algorithm (Backcalc, Galvez et al., 2015) with the thermo-mechanical code I2VIS (Gerya and Yuen, 2003) to investigate FMM. Specifically, the speciation and fractionation of electrolytic fluids are governed by cell-wise calculation from Backcalc, and fluid migration is computed assuming incompressible two-phase flow, whereby pore fluid pressure is assumed to be equal to the solid pressure (Faccenda et al., 2009). This new modelling platform is capable of capturing the chemical feedbacks on the geodynamic evolution of subduction zones. Our preliminary efforts have been to replicate the major elements fluxes from a kinematic model presented by Zhong and Galvez (2021) to test the successful combination of the codes. Our ‘benchmark’ tests show excellent agreement. Here, we will present some preliminary tests incorporating mechanical deformations of layers, and how such process, including mantle diapirism, may affect the trajectory of fluids and metasomatic pathways.
Reassessing the role of diatoms in carbon transfer through the Southern Ocean Twilight Zone
Authors: Williams Jack , Giering Sari , Baker Chelsey , East Hannah , Espinola Benoit , Le Moigne Fred , Villa Maria , Pabortsava Katsiaryna , Blackbird Sabena , Pebody Corinne , Saw Kevin , Moore Mark , Henson Stephanie , Sanders Richard , Martin Adrian
Published: March 2024

Diatoms, a ubiquitous group of phytoplankton, account for approximately 40% of particulate organic carbon (POC) exported via the ocean biological carbon pump, which modulates atmospheric CO2. Diatoms are represented in global biogeochemical models as effective vectors for sinking POC, with their large size and dense skeletons made of biogenic Silica (BSi) thought to allow rapid transfer of organic carbon to the ocean interior. However, we observe this not to be the case across large parts of the Southern Ocean mesopelagic zone. Here we present direct flux measurements from different sectors of the Southern Ocean demonstrating that silica and carbon cycles in the Southern Ocean mesopelagic are strongly decoupled, with a weak mechanistic link between BSi and POC fluxes. By combining Marine Snow Catcher flux measurements, in-situ pump, and CTD particulate data, we show that for a large part of the productive season, diatoms do not represent efficient vectors of sinking POC through the mesopelagic, yet POC is still efficiently transferred to depth. We suggest that processes influencing flux attenuation differ between the upper mesopelagic and deep ocean, with rapid BSi flux attenuation in the upper mesopelagic caused by elevated rates of BSi remineralization or negation of biomineral ballast effects by particle processes such as buoyancy regulation or fragmentation. Biomineral ballast may yet play an important role in shaping the efficiency of sinking POC transfer in the deep ocean. More broadly, these results highlight the need to understand the nuanced role this key taxon plays in transferring carbon through the mesopelagic, a region that is highly vulnerable to climate change effects and key in shaping the efficiency of downward carbon transport. As diatoms appear to be inefficient at delivering carbon to the deep ocean, projected losses in the strength of the Southern Ocean BCP due to shifts in phytoplankton community composition to smaller size classes may be less than previously predicted.
Advancing Ionospheric Predictions in North Africa: A Deep Learning Approach Integrating Ground and Satellite GNSS observations
Authors: Nooreldeen Hassan , Mahrous Ayman , Ahmed Ayman , Yossuf Mohamed , Shaker Abdallah , Salloumah Amira
Published: March 2024

The North Africa region faces significant challenges due to the need for ionospheric ground observational data, complicating efforts to achieve accurate predictions. Our study strategically integrates ground and satellite-derived ionospheric data from Global Navigation Satellite System (GNSS) observations to address this pivotal gap. Leveraging this extensive dataset, we implemented a sophisticated Deep Neural Network (DNN) methodology, resulting in a notable advancement in predicting ionospheric irregularities stemming from space weather phenomena. Our approach meticulously utilized two years of Vertical Total Electron Content (VTEC) data sourced from 12 strategically located GNSS ground stations that span a geographical range from 0°N to 40°N latitudes and 25°W to 50°E longitudes. This focused dataset aimed to enhance the accuracy and reliability of predictions tailored explicitly for the North African context.
Moreover, we seamlessly integrated critical geomagnetic indices—including Dst, F10.7, and KP— to bolster our predictive capabilities with the GNSS-derived VTEC data. This intricate fusion facilitated the training of our DNN-LSTM model on robust time-series datasets, empowering it to deliver forecasts characterized by spatial precision and temporal relevance. Notably, when comparing DNN prediction to the IRI2020 model, our DNN-based approach showcased higher accuracy, evidenced by reduced RMSE values. Our research illuminates the immense potential of integrating ground and space-based data with machine learning paradigms. Such integrative methodologies hold promise for advancing ionospheric studies, especially in regions characterized by sparse ground station coverage, thereby enriching our comprehension of ionospheric dynamics.
Ecosystem water relations
Authors: Binks Oliver
Published: March 2024

‘Water potential’ is the biophysically relevant measure of water status in vegetation relating to stomatal conductance, hydraulic conductance, and mortality thresholds; yet this cannot be directly related to fluxes of water at plot- to landscape-scale without understanding its relationship with ‘water content’.  The relationship between water content and water potential has long been of interest to plant and soil scientists and is typically determined at small scale on excised plant parts or soil samples.  But how can water potential be scaled from leaf to canopy, branch to stem, tree to forest?  How does water content vary throughout a plant, and across individuals and species?In this talk I will outline some practical considerations for deriving representative values for ecosystem water potential and content: the ecosystem pressure-volume curve.  I will discuss how ecosystem water status is influenced by the boundaries we apply to the system, which differ depending on whether we are interested in interpreting remote sensing data, models, or field measurements.  And I will describe the concept of the ‘state-based’ model which relates to steady-state vegetation types that emerge predictably in response to a given climate or hydraulic environment.To support this discussion, I will present ecosystem pressure-volume curves from nine sites including tropical rainforest, savanna, temperate forest, and a long-term Amazonian rainforest drought experiment.  The results from these preliminary analyses show that the relationship between the water stored in biomass consistently scales with biomass across systems, as does the vegetation-level hydraulic capacitance; while the relative measures of water storage and hydraulic capacitance show no trend across ecosystems.  Such cross-biome relationships in water relations hold promise for improving our understanding of vegetation-climate feedbacks over large spatial and temporal scales, and enhancing our capacity to interpret remote sensing data.
Testing a new Radar QPE methodology for winter events with a low melting layer
Authors: Evaristo Raquel , Chen Ju-yu , Ryzhkov Alexander , Trömel Silke
Published: March 2024

The RY precipitation product of the German Weather Service (DWD) is severely affected by the presence of the low melting layer and frequently shows circular features of enhanced precipitation around the radar sites during the winter time. The radars tend to be installed at relatively high terrain and to scan at elevations at a minimum of 0.5° in order to avoid beam blockage and ground clutter. In doing so two problems arise:1) the difference between the ground and the radar beams becomes a problem especially at large distances from the radar, and consequently precipitation processes in the lowest layers are not observed.2) the radar beam often reaches the melting layer and may even cross it where it is sampling the snow above.As a result problems arise when deriving surface QPE from the radar: regions of enhanced QPE in ring shapes around the radar sites, and underestimation of the precipitation beyond the melting layer.A new methodology (PVPR - Polarimetric Vertical Profile of Reflectivity) developed by Ryzhkov et al. 2022 is tested here for which the radar reflectivity (ZH) is reconstructed to correct for the effect of the melting layer and snow beyond. In this methodology the melting layer is detected independently for each azimuth based on the values of ZH and ρHV (cross-correlation coefficient between horizontal and vertically polarized radar waves). In particular the range bin at which the melting layer was reached is recorded (mlb_r). The strength of the melting layer (ML_S) is defined based on how much the value of ρHV  dropped within the melting layer. The values of ML_r and ML_S at a specific elevation are considered sufficient to characterize the melting layer, and are then compared with lookuptables which were generated by simulations of the melting layer effect on the radar beam. A correction factor is then applied based on the lookuptables to the ZH profile within and beyond the melting layer. Visually the result shows a smoother field of reflectivity without the obvious bright band and decreased values associated with snow at farther ranges.In this study the PVPR methodology was used to correct ZH which in turn was used to calculate rain rates and rain accumulations in a few winter events in Germany.  The results show a strong improvement in the quality of the QPE when compared to rain gauges. The quality of the resulting QPE depends on the event and on the location of the radar. More specifically, the quality decreases when the melting layer is very low, at heights comparable to the radar height, and when the difference between the beam and the surface increases. These problems will be analyzed and potential solutions will be tested in order to improve the quality of the rainfall product.Ryzhkov, Alexander, Pengfei Zhang, Petar Bukovčić, Jian Zhang, and Stephen Cocks. 2022. "Polarimetric Radar Quantitative Precipitation Estimation" Remote Sensing 14, no. 7: 1695. https://doi.org/10.3390/rs14071695 
The lifecycle of a relict periglacial boulder landscape, southern Appalachians, USA
Authors: Fame Michelle , Chilton Kristin , Spotila James , Kelly Meredith , Caton Summer
Published: March 2024

The deposition of large, resistant boulders on hillslopes and in channels can have an armouring effect on the landscape leading to a decrease in erosion rates, a decrease in the efficiency of downslope sediment transport, and a coeval mismatched increase in slope angle. Such boulder accumulations are a significant component of hillslopes and channels in the southern Appalachian Mountains and influence the landscape's morphology. It has long been speculated that these boulder deposits originated during Quaternary glacial advances under the influence of periglacial processes operating in cold regions south of the maximum extent of the Laurentide Ice Sheet. However, no prior work has tied these features to a specific time or climatically modulated mechanism. By testing and refining the hypothesis of the periglacial origin of these relict boulders and the mechanisms driving their initial deposition and subsequent reworking we hope to contribute to our understanding of the climatically correlated timescales over which contemporary warming can be expected to be a dominating influence on modern boulder armoured periglacial alpine and arctic landscapes.In this study, we investigated the lifecycle of such boulder deposits by determining cosmogenic 10Be exposure ages from large boulders on hillslopes and in channels in the Virginia Appalachians, United States. The correlation between the resulting boulder exposure ages (101.7 ± 6.9 ka to 10.8 ± 0.8 ka; n = 23) and the most recent Wisconsin Glacial Stage and subsequent deglaciation (~115 – 11.7 ka) supports their periglacial origin. The lack of exposure ages corresponding to the Last Interglacial Stage or following Wisconsin ice retreat suggests interglacial non-deposition and stability. The absence of exposure ages from the penultimate Illinoian or older Quaternary Glacial Stages suggests that periglacial hillslope processes allow the landscape to be resurfaced with large boulders during each return to cold climate conditions. This cyclic resurfacing of hillslopes and channels is an example of how climatic oscillations insert disequilibrium into the landscape cycle and contributes to our appreciation of the timescales over which climate change may impact boulder landscapes in modern periglacial environments.