bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of organo-Fe (oxyhydr)oxide interactions during the first stages of Martian regolith simulant terraforming
Authors: Giannetta Beatrice , Caporale Antonio G. , Oliveira De Souza Danilo , Adamo Paola , Zaccone Claudio
Published: February 2023

Future long-term space missions beyond Low Earth Orbit (e.g., to Mars) depend on the development of bioregenerative life support systems able to produce food crops based on in situ resource utilization. Mars regolith potentially contains most of the essential nutrients for plant growth, except for organic matter (OM). Several strategies and treatments can be applied to improve nutrient deficiency of simulants and enhance their performance as plant growth substrates. Although Mars regolith simulants have been characterized by mineralogical, physico-chemical and hydraulic properties, no data are available to date in the scientific literature about the stabilization of exogeneous OM by minerals, including iron (Fe) oxides, over time.This study aims at understanding the mineral transformation and OM turnover in the early stages of terraforming. The Mojave Mars Simulant MMS-1, alone (R100) and with a commercial compost 70:30 v:v (R70C30), was compared to a fluvial sand, alone and with compost (S100 and S70C30). Potato was grown on these substrates for 99 days in greenhouse. Samples were fractionated, obtaining particulate OM (POM) and mineral associated OM (MAOM), andcharacterized for total nitrogen and organic carbon (OC), total element concentration (ICP-OES) and by Fe K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS).In the whole medium, OC increased in S70C30 (10×) and R70C30 (25×). As expected, most of the OC accumulated in the POM fraction of both growing media (10× in S70C30 and 20× in R70C30), while OC in the MAOM was 3-times higher in R70C30 than in S70C30. Chlorite, smectite and goethite were the main Fe species in S100, according to XANES, while Fe(III)-OM was found in both fractions of S70C30. Moreover, according to EXAFS, hematite occurred in POM, whereas goethite in MAOM. XANES revealed the occurrence of smectite, maghemite and ferrihydrite in R100, and of nontronite and hematite in the MAOM and POM, respectively.Revealing Fe species involved in the formation of organo-mineral interactions will help to identify the main critical aspects and future challenges related to sustainable space farming improving the in-situ use of Martian resources.
Recovery of rare earth elements from fluorite sludges from dicalcium phosphate industry
Authors: Grandia Fidel , Plachciak Marcin
Published: February 2023

The management and final disposal of waste containing radioactive elements is currently challenging in many countries due to the large volumes and their potential radiological risk. A promising alternative is the re-use to reduce the amount of waste to be disposed and to provide additional profit to the companies that generates this residue. This can be the case of fluorite sludge produced after the manufacturing of dicalcium phosphate. In this study, the initial stage of waste characterisation of fluorite sludge from two industrial sites, one active in Flix (NE Spain) and another one consisting of legacy ponds and stockpiles at El Hondón, in SE Spain, is reported. Fluorite sludge consists of 40-60% of CaF2, which precipitates during the reaction between fluorapatite (main component of phosphorite raw material) and HCl. This fluorite is very fine grained, with most particle sizes below 5 microns, and contains significant amounts of REEs, mainly Y, La, Ce and Nd, (0.2wt%, 800 ppm, 600 ppm and 300 respectively), especially in the sludge that precipitated in the reaction tanks. Concentration of the other REEs vary from 18 ppm to 167 ppm. Prices for the top grade REEs are high at the moment, and with time, as the reserves become scarcer, the prices will grow even more. Also, fluorite concentrate can be a valuable commodity. Taking into account the large amounts of disposed waste in both sites, and the concentrations of REEs, their recovery can be a great opportunity to reduce the amount of waste to be managed, and to provide new sources for these critical raw materials. So, current investigations are focused on cost-effective methodologies of fluorite separation and concentration and REEs extraction. 
Influence of meteorology on the variations of crustal seismic velocity in Volcan de Colima, Mexico using Noise Interferometry
Authors: Ibarra Morales Juan , De Plaen Raphael S. M. , Márquez Ramírez Víctor Hugo , Zúñiga Dávila-Madrid Francisco Ramón , Arámbula Mendoza Raul
Published: February 2023

The temporal variation of seismic velocity gives us information about the crust’s stress state and the relative changes associated with magmatic, tectonic, and meteorologic activity. In the present study, we analyze the temporary seismic velocity changes under Volcan de Colima to identify its relationship with volcanic and non-volcanic sources, evaluate the seasonality of the variations and describe the impact that the meteorology has on the changes. The signals of seismic velocity variation used in this work were measured using the single-station cross-component correlation technique applied to traces registered at four stations in the period 2013 – 2017. The data was analyzed in two frequency bands: 0.1 – 1 and 1 – 2 Hz.We validate the relationship between the velocity variations and three meteorological parameters, rain, temperature, and atmospheric pressure, using wavelet coherence analysis. After fitting a linear model, we identified the environmental factors with the most impact on the seismic velocity are: 1) the rainfall-induced pore pressure, correlated negatively with the seismic velocity and causing changes close to the order of -0.5%; 2) thermoelastic strains correlated positively with the seismic velocity and causing velocity variations between -0.5 and 0.5%. Atmospheric pressure has a smaller impact, mainly of the order of 10-3%.
Microbial carbon use efficiency in soil under N deposition: Meta-analysis of 13C and 18O approaches
Authors: Kuzyakov Yakov , Hu Junxi , Huang Congde , Zhou Shixing
Published: February 2023

The carbon use efficiency (CUE) of soil microorganisms is a critical parameter for the first step of organic carbon (C) transformation by and incorporation into microbial biomass and shapes C cycling in terrestrial ecosystems. As C and nitrogen (N) cycles interact closely and N availability affects microbial metabolism, N addition to soil may shift the microbial CUE. We conducted a meta-analysis (100 data pairs) to generalize information about the microbial CUE response to N addition in soil based on the two most common CUE estimation approaches: (i) 13C-labelled substrate addition (13C-substrate) and (ii) 18O-labelled water addition (18O-H2O).The mean microbial CUE in soils across all biomes and approaches was 0.37. The effects of N addition on CUE, however, were depended on the approach: CUE decreased by 12% if measured by the 13C-substrate approach, while CUE increased by 11% if measured by the 18O-H2O approach. These differences in the microbial CUE response depending on the estimation approach are explained by the divergent reactions of microbial growth to N addition: N addition decreases the 13C incorporation into microbial biomass (this parameter is in the numerator by CUE calculation based on the 13C-substrate approach). In contrast, N addition slightly increases (although statistically insignificant) the microbial growth rate (in the numerator of the CUE calculation when assessed by the 18O-H2O approach), significantly raising the CUE. We explained these N addition effects based on CUE regulation mechanisms at the metabolic, cell, community, and ecosystem levels. Consequently, the differences in the microbial responses (microbial growth, respiration, C incorporation, community composition, and dormant or active states) between the 13C-substrate and 18O-H2O approaches need to be considered. Thus, these two CUE estimation approaches should be compared to understand microbially mediated C and nutrient dynamics under increasing anthropogenic N input and other global change effects.ReferenceHu J, Huang C, Zhou S, Kuzyakov Y 2022. Nitrogen deposition affects microbial carbon use efficiency: Meta-analysis of similarities and differences in 18O and 13C approaches. Global Change Biology 28 (16), 4977-4988. http://doi.org/10.1111/gcb.1622
Septarias in the Babouri-Figuil Basin (Northern Cameroon): Morphology and controls on emplacement.
Authors: Tonye Marie Diane , Bisse Salomon Bertrant , Manga Owona Gaspard William , Belinga Belinga Cédric , Secke Bekonga Gouott Boris , Ekomane Emile
Published: February 2023

The Babouri-Figuil Basin is located in the northern part of Cameroon and is part of the Bénoué trough. One of the most remarkable features of this basin is the presence of carbonate concretions commonly called septaria. However, the understanding of nature of these concretions remains limited. In the first phase of this study a detailed field work was carried in the basin. The Babouri-Figuil Basin has four lithofacies encompassing limestones, marlstones, sandstones and conglomerates. Its depositional environment is fluvial to fluviolacustrine. These facies are organized in asymmetrical synclines and crossed by basaltic intrusions. The concretions identified occurs in the marly facies. Numerous descriptive criteria noted in the field made it possible to give their size, their context of establishment, as well as the factors which control the forms of these septarias. These septarias are greyish or dark brown and massive in structure. Their size varies from 15-57.5 cm with circumferences ranging from 23-87cm. They also have intersection cracks due to their maturity or aging. These intersection of septarian cracks are filled and indicate different generations. Ovoid, rounded, disc, elongated and chocolate bar morphologies have been observed in the study area. These shapes are controlled by the thickness and shape of the marls. Thus, where the thickness is important, the septarias are well developed and generally take ovoid, rounded or spherical shapes because the marl has weak planes. On the other hand, when the thickness of the marl is thin or in lens, the septarias tends to follow only the space and the shape that the marl occupies and, tending to make it disappear, thus creating elongated, flattened and even rounded shapes. Consequently, the septarias of the Babouri-Figuil Basin is post-sedimentary to the marl deposits.
A Novel Framework for the Assessment of Heat-Wave Risks and Nature-Based Solutions (NBS) Impacts
Authors: Brogno Luigi , Barbano Francesco , Leo Laura Sandra , Di Sabatino Silvana
Published: February 2023

Current climate change projections show that the probability of occurrence and the magnitude of heat-wave events are increasing worldwide. These events have to be considered as higher risks for territories and ecosystems, especially where vulnerability is high. The occurrence of heat waves translates into several potential damages such as an increase in fatalities and production losses, degradation of natural and cultural heritages, or the triggering of other hazards such as wildfires. The overlap of all these consequences may lead to both relevant economic losses and additional CO2 emissions affecting our resilience and exacerbating in turn climate change.In this context, we propose a novel framework for the assessment of risks resulting from heat waves with the aim of quantifying the main contributions to economic losses and CO2 emissions. This framework follows the conceptual definition of risk provided by the Intergovernmental Panel on Climate Change (IPCC) as the product of hazard, exposure, and vulnerability components. The newly-proposed formulation of these components includes the concept of Nature-Based Solutions (NBS) as strategies carried out to enhance our adaptive capacity in a sustainable and cost-effective way. Since NBS consist of natural features that are also exposed to heat waves, the entire life cycle of NBS is considered (i.e., the implementation, maintenance, and possible restorations). The proposed framework stands as a tool for assessing the local impacts of already-implemented or designed NBS in the current and future climate scenarios.
How is geometrical complexity in fault zone recorded by geodesy and seismology?
Authors: Almakari Michelle , Bhat Harsha S. , Kheirdast Navid , Villafuerte Carlos , Thomas Marion Y.
Published: February 2023

Over the last decades, new observations of complex slip dynamics have emerged. We now observe a continuum of transients energy release happening on fault systems, such as slow slip events, LFEs and tremors. Present quasi-dynamic numerical models are capable of producing such complex slip events on fault planes by considering more realistic complex fault geometries. We aim in this study to bridge the gap between source modeling and observations by generating synthetic surface records. For this, we consider a fault system which consists of a main self-similar rough fault, surrounded by a dense network of off-fault fractures. We embed our 2D quasi-dynamic fault zone in a 3D elastic half-space and cover the free surface with a wide array of colocated broadband accelerometers and high rate GPS stations. Over multiple seismic cycles, we record broadband signals at 50 Hz and high rate GPS at 1 Hz. We aim to understand how the different sequences of complex behavior that we observe on the fault plane are recorded on the stations. What are the different contributions of the main fault and off-fault fractures to the radiated signals recorded on the stations? 
Revisiting the global mean ocean mass budget over 2005-202
Authors: Barnoud Anne , Pfeffer Julia , Cazenave Anny , Fraudeau Robin , Rousseau Victor , Ablain Michaël
Published: February 2023

We investigate the performances of GRACE and GRACE Follow-On satellite gravimetry missions in assessing the ocean mass budget at global scale over 2005-2020. For that purpose, we focus on the last years of the record (2015-2020) when GRACE and GRACE Follow-On faced instrumental problems. We compare the global mean ocean mass estimates from GRACE and GRACE Follow-On to the sum of its contributions from Greenland, Antarctica, land glaciers, terrestrial water storage and atmospheric water content estimated with independent observations. Significant residuals are observed in the global mean ocean mass budget at interannual time scales. Our analyses suggest that the terrestrial water storage variations based on global hydrological model likely contributes to a large part to the misclosure of the global mean ocean mass budget at interannual time scales. We also compare the GRACE-based global mean ocean mass with the altimetry-based global mean sea level corrected for the Argo-based thermosteric contribution (an equivalent of global mean ocean mass). After correcting for the wet troposphere drift of the radiometer on-board the Jason-3 altimeter satellite, we find that mass budget misclosure is reduced but still significant. However, replacing the Argo-based thermosteric component by the ORAS5 ocean reanlaysis or from CERES top of the atmosphere observations leads to closure of the mass budget over the 2015-2020 time span. We conclude that the two most likely sources of error in the global mean ocean mass budget are the thermosteric component based on Argo and the terrestrial water storage contribution based on global hydrological models. The GRACE and GRACE Follow-On data are unlikely to be responsible on their own for the non-closure of the global mean ocean mass budget.
Carbon allocation to root exudates in a mature mixed F. sylvatica – P. abies forest under drought and one year after drought release.
Authors: Hafner Benjamin D. , Brunn Melanie , Zwetsloot Marie J. , Hikino Kyohsuke , Weikl Fabian , Pritsch Karin , Sayer Emma J. , Ruehr Nadine K. , Bauerle Taryn L.
Published: February 2023

In recent years, important processes controlling ecosystem carbon dynamics have been connected to fine-root exudation of soluble carbon compounds. Root exudation patterns may change depending on plant interactions and plant susceptibility to and recovery from drought. Recent investigations suggest that root exudation tends to increase with stress events, but quantification of the amount of carbon released from roots across soil depths with differing water availability and species interactions are missing.We tested if root exudation rates were negatively correlated with soil water content across soil depths during and after drought. We further tested if species in mixture, often considered to be less stressed under drought, exuded less carbon than species in monospecific environments. Exudates were sampled in a mature Fagus sylvatica L. and Picea abies (L.) Karst. forest at the end of a five-year throughfall exclusion period and again one year after the drought ended. We quantified root exudates and their variation with soil depth for both tree species in monospecific and mixed species zones.Carbon exudation significantly increased in fine roots exposed to dry soils (< c. 10vol-% SWC), with fine roots growing in driest surface soils exuding the most. Under drought, the proportion of net assimilated carbon allocated to exudates doubled for F. sylvatica and tripled for P. abies, respectively. One year after drought release, carbon allocation to exudates was not different for F. sylvatica between previously drought stressed and control trees, while the proportion was still significantly increased in previously drought stressed P. abies compared to control trees. This indicates long-term disruptions in carbon allocation patterns even after the end of a drought period in evergreen vs. broadleaved temperate tree species. Both species exuded significantly more carbon when in monoculture than when in a mixed zone, especially in the surface soil layer.Our results demonstrate that carbon is released preferentially in the surface soil layers exposed to more variable soil water contents and exudation amounts are maintained by allocating bigger proportions of net-assimilated carbon into exudates even among variable carbon assimilation rates throughout periods of drought and re-wetting. In addition, plant interactions significantly influenced root exudation patterns. Further studies are planned to understand if differences in exudate quantity correlate to differences in functioning of released exudates in monospecific and mixed environments by analyzing the chemical profile of the exudate metabolome.
Effect of Nanohydroxyapatite in Lowland Rice and Simulation of Phosphorus Transport using Hydrus-1D
Authors: Pohshna Chwadaka , Mailapalli Damodhara Rao
Published: February 2023

Excessive phosphorus (P) application through conventional fertilizers to maintain crop yield has increased P pollution and created environmental concerns with serious implications on surface and ground waters. To improve the P nutrient uptake and minimized the undesirable impacts of conventional P fertilizer, nanoparticle such as hydroxyapatite nanoparticle (HANP) was synthesized using the phosphoric acid-treated calcinated chicken eggshells in a planetary ball mill. The synthesized HANP was used as a P nutrient source for lowland rice and the effects on rice agronomical parameters (plant height, tiller count, biomass and yield), P transport and leaching in rice soil with the application of HANP as a P source were studied alongside conventional fertilizer (SSP) and control experiments (CNT) for three seasons (Rabi 2018-19, Kharif and Rabi 2019-20) using field columns. Then the water flow and P transport were simulated with the help of the Hydrus-1D model. The nanoparticles size HANP resulted after 10 hours of milling with a milling speed of 500 rpm and they were observed to be mostly oval in shape with an average particle size of 105 nm. The field column studies indicated an improved plant height, tiller count and yield with HANP and SSP treatment as compared to CNT treatment. No significant difference was observed between HANP and SSP treatment. A significant difference in ortho-P concentration between HANP and SSP treatment was observed in both ponding water and leachate water with higher ortho-P concentrations in SSP as compared to HANP treatment. The simulation results indicated that the Hydrus-1D model successfully simulated the bottom flux and the ortho-P concentration in the leachate very well with a good coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE) and root mean square error (RMSE) values. The value of distribution coefficient Kd was found to be higher in the case of HANP as compared to SSP treatment indicating that more adsorption of P to soil particles occurs in HANP treatment. While the longitudinal dispersivity and the diffusion or precipitation rate constant were approximately higher in SSP treatment than in HANP treatments indicating less local variations in the velocity field of ortho-P in the direction of fluid flow, and a lower dissolution rate of HANP treatment as compared to SSP treatment. Thus the potential of HANP for use as P fertilizer can be demonstrated by the ability to sustain the agronomical parameters of rice crops and the reduced leaching rate and slow-releasing property of the material.Keywords: Hydroxyapatite, phosphorus, rice, nanofertilizer, Hydrus 1D model
Modelling multi-decadal sediment delivery to rivers by debris flows and lahars with SedCas
Authors: Bennett Georgina , Christie James , Hirschberg Jacob , Nicholas Andrew , Vahidi Ellie , Team EvoFlood
Published: February 2023

Debris flows and lahars convey large quantities of sediment through fluvial systems in mountainous and volcanic regions. Constraining decadal to centennial patterns of sediment transport by these potentially destructive flows is crucial for understanding their drivers and subsequently modelling the evolution of downstream hazard and channel morphology with time. Relatively few modelling frameworks have been designed to capture sediment transport dynamics at these timescales. Existing models instead tend to either 1) simulate the runout of individual debris flow events or 2) forecast landscape evolution over longer millennial timescales. Our work seeks to address this research gap by developing SedCas. SedCas is a spatially lumped sediment cascade model developed to simulate decadal patterns of sediment transport by debris flows from the Illgraben, an Alpine catchment in Switzerland, into the Rhône River. Its relatively simple structure is computationally inexpensive and has enabled its use in forecasting debris flow hazard and sediment yield from the Illgraben over the 21st century in response to a range of climate change scenarios. Here, we present the first application and adaptation of the SedCas model framework to non-alpine catchments. Firstly, we simulate sediment transport by lahars in a catchment on the island of Montserrat which has been disturbed episodically by explosive volcanism between 1995 - present. In this model iteration, SedCas_Volcano, we account for variations in vegetation cover induced by eruptive events, in addition to water and sediment supply. The model results capture the first-order patterns (aggregate magnitude-frequency) of the largest observed lahars, and the timing and relative order of magnitude of fluctuations in sediment yield. Seasonal and interannual variations in lahar activity are not fully captured, however. We attribute these shortfalls to limitations of available data and the model not accounting for important dynamic hydrological processes that alter runoff generation on evolving volcanic deposits. These limitations in turn provide avenues of further research and development. Secondly, we present preliminary experiments to simulate bedload sediment delivery as input into a new global flood model that accounts for evolving channel geometry.
The metasomatism affecting karstic bauxites from the south-central Pyrenees, Catalonia (NE Spain) and its implications on the REE geochemistry in similar geological settings.
Authors: Roqué-Rosell Josep , Granado Pablo , Martín-Martín Juan Diego , Ibáñez-Insa, Jordi , Pérez Bustos Ivanna , Roca-Miró Roger , Jiménez Franco Abigail
Published: February 2023

Karstic bauxite deposits are the main resource of aluminum in Europe and are formed through a combination of weathering, leaching, and deposition processes known as bauxitization. Bauxites have recently been proposed as unconventional resources of rare-earth elements (REE) as well. The studied karstic bauxite deposits are located on the salt-detached Serres Marginals thrust sheet, at the external most unit of the south-central Pyrenees (Catalonia, NE Spain). The Pyrenean bauxites are found overlaying and filling karstic surfaces forming aligned pockets up to several meters thick. These deposits have been mined for more than 20 years and present high variability in SiO2, Al2O3 and Fe2O3 contents. Here, we characterize these deposits for the first time by a combination of field geology, XRD, FTIR and XRF to determine their formation, mineralogy, and geochemistry and to understand the causes affecting their compositional variations. Field data indicate that the bauxite deposits fill a paleokarst system affecting Dogger dolostones and/or Tithonian-Berriasian limestones. XRD data indicate that the studied karstic bauxites are mainly composed of Al-rich minerals kaolinite and boehmite, in addition to the Fe-oxide hematite, and lesser amounts of the Ti-oxides rutile and anatase. The detailed study of the FTIR spectra also confirmed the presence of diaspore and dickite. XRF data confirm the presence of varying amounts of Al, Fe and Si in addition to varying low contents of REE. These results suggest that boehmite was formed first during bauxitization and later transformed to diaspore, kaolinite and finally to dickite upon metasomatism. The presence of dickite in faults and fractures provides a direct proof for such fluid circulation. Our results suggest that the mechanisms responsible of the compositional variations in karstic bauxites are rather complex and fall beyond the standard bauxitization processes. The observed metasomatism should be further assessed, since the inferred fluid-rock interactions are susceptible to affect and mobilize REE not only in the south-central Pyrenees karstic bauxites but elsewhere in similar geological settings.
Increased summer storms will reduce bottom water oxygen concentrations in a temperate shelf sea.
Authors: Meng Xin , Sharples Jonathan , Mahaffey Claire
Published: February 2023

Oxygen is a vital resource in the ocean, particularly for the high oxygen demand consumers such as fish. In temperature shelf seas, the bottom water oxygen is frequently seen to decrease during the stratified period as a natural consequence of organic matter being remineralised and the seasonal thermocline preventing the replenishment of oxygen from the atmosphere. However, the subsurface chlorophyll maximum (SCM) is a generator of oxygen in the base of the thermocline. Mixing across the thermocline by episodic strong wind events could supply oxygen from the SCM into the bottom water and so offset some of the oxygen reduction arising from organic matter degradation. To explore this possibility, we set up a simple 1-D numerical model to simulate the seasonal cycle of stratification, phytoplankton, nutrients and oxygen in a temperate shelf sea. By adding strong wind mixing, the oxygen concentration in the bottom water becomes lower by the end of autumn than in the case with no wind events. This paradoxical result occurs because the wind mixing also brings organic matter from the SCM into the bottom water, which increases respiration and degradation. A warmer climate will lead to lower oxygen concentrations simply as a result of the reduction in oxygen solubility in seawater; our results also suggest that any climate-driven increases in wind mixing could further worsen bottom water oxygen conditions in temperate shelf seas.
A compact general-purpose Doppler Lidar for lidar networks
Authors: Froh Jan , Höffner Josef , Mauer Alsu , Mense Thorben , Eixmann Ronald , Baumgarten Gerd , Lübken Franz-Josef , Munk Alexander , Scheuer Sarah , Strotkamp Michael , Jungbluth Bernd
Published: February 2023

We present the state of the VAHCOLI (Vertical and Horizontal COverage by Lidar) project for investigating small- to large-scale processes in the atmosphere. In the future, an array of compact lidars with multiple fields of view will allow for measurements of temperatures, winds and aerosols with high temporal and vertical resolution.Doppler lidars, in particular resonance Doppler lidars, with daylight capability are challenging systems because of the small field of view, spectral filtering and other additional subsystems required compared to observations at night. We developed a universal Doppler lidar platform (~1m3, ~500kg) with all required technologies for automatic operation. The system is capable of studying Mie scattering (aerosols), Rayleigh scattering (air molecules), and resonance fluorescence on free potassium atoms in the middle atmosphere from 5 km to 100 km. Unique spectral methods and narrowband optical components allow precise wind, temperature, and aerosol measurements by studying the Doppler shift and broadening of the scattered signals. The combination of cost-efficient design and fast assembling of such a system allows the construction of a Doppler lidar network with identical unitsWe will show the latest results and discuss the next scientific and technical steps for network operation and transferring the technology into industry.
Understanding the Intermodel Spread of Simulated Arctic September Sea-Ice Sensitivity
Authors: Stolla M. Katharina , Schmidt Hauke , Notz Dirk
Published: February 2023

We investigate the reasons for the intermodel spread of simulated Arctic September sea-ice sensitivity. Previous studies have found that Arctic September sea-ice area declines linearly with cumulative CO2 emissions both in observations and climate-model simulations. However, the models’ sensitivity differs substantially, with the models generally underestimating the sensitivity of sea-ice area to CO2 emissions. We here examine the reasons for the large intermodel spread in order to be also able to understand the general underestimation.We identify a chain of processes contributing to the overall sea-ice sensitivity and investigate the simulation of each sub-process separately in each CMIP6 model. The process chain considers the global-mean temperature response to CO2 increase, Arctic amplification, the increase in incoming longwave radiation, the total non-shortwave heat flux in the Arctic, and the resulting sea-ice loss. In addition, we separately examine the impact of the simulated incoming longwave radiation for the spread of sea-ice sensitivity. Doing so, we find that clouds play a minor role for the spread of simulated incoming longwave radiation but that temperature rise and water vapour content in the Arctic are relevant.Based on these analyses, we identify three processes whose different representation in climate models likely is the main cause for the intermodel spread of simulated sea-ice sensitivity, and which need to be improved to improve the modeled sensitivity of Arctic sea ice: firstly the global-mean temperature response to CO2 increase, secondly the Arctic amplification and thirdly local sea-ice processes. The first two factors highly impact the evolution of temperature in the Arctic which affects the incoming longwave radiation and thus the evolution of sea ice.
Regional assessment of soil type and land occupation influence on ecosystem services
Authors: Chirol Clémentine , Derrien Delphine , Saint-André Laurent , Séré Geoffroy
Published: February 2023

As highlighted by recent regulations in Europe and worldwide, the multifunctionality of soils and their capacity to deliver services to societies are of increasing importance to land planners and decision makers. Soils provide multiple ecosystem services (ES) including food production, biomass-energy and contribution to climate change regulation through carbon storage. These services need to be estimated and visualised at relevant scales in order to improve their consideration in land planning decisions.This project aims to map interdependent bundles of soil ecosystem services at a regional scale so that the effect of land planning decisions on ES delivery can be apprehended by stakeholders. The study site is a 320 km2 rural region in Meuse/Haute Marne, France, composed of 56% cropland, 30% forest and 14% grassland. The pedological properties are provided by 85 soil profiles, grouped into 8 dominant soil types, and a 1/50,000 pedological map. Soil typology is dominated by Calcaric cambisols in the agricultural valleys, but features also deep silty and acidic soils in the forested plateaus, shallow rocky calcaric soils on the hillslopes, and deep clay-rich hydromorphic soils in the alluvial valleys.Using an expert-based decision support model (Destisol1), soil functions and ecosystem services were scored for all spatial units defined by soil type, slope category and land cover. Functions are calculated based on the soil bio-physico-chemical properties across the whole depth of the pedons. Scores, ranging from 0 to 3, are based on expert-based rules defining threshold values for all soil indicators. Correction factors are applied to the ecosystem service scores to account for the effect of land cover. Finally, correlated bundles of ES across all spatial units are obtained by principal component analysis.Our results synthetise the effect of soil type on ecosystem services provision, and display the spatial synergies and tradeoffs through three maps of ES bundles. The first ES bundle map compiles the provisioning services (food production, provision of construction wood, provision of biomass energy), which depend dominantly on land use. The second map shows the hydrological regulating services (water quality, erosion mitigation and flooding mitigation), which depend on slope, land use and soil hydromorphy. The third map shows the climate and biological regulating services (contribution to climate change regulation through carbon storage, local cooling effect, biodiversity), which depend on land use, soil depth, rock fragment content and organic matter content. Going forward, maps of ES bundles could be generated for different land planning scenarios to assess the ensuing losses and gains of ES, and promote a more holistic consideration of soil ES by stakeholders.Reference: 1. Blanchart, A. et al. Towards an operational methodology to optimize ecosystem services provided by urban soils. Landsc. Urban Plan. 176, 1–9 (2018).
Magnesium content and groundwater flow in limestone aquifers: a relationship with potential developments for exploitation management of karst springs.
Authors: De Filippi Francesco Maria , Sappa Giuseppe
Published: February 2023

Karst aquifers are characterized by different types of groundwater flow, related to different types of permeability due to the simultaneous presence of matrix, fractures and conduits. The presence of a well-developed karst conduit system leads to a fast circulation of groundwater, within the aquifer and an impulsive response of the spring flow to the rainfall inputs, with a potential fast transport of contaminants from the hydrogeological basin surface to the output.In this study, the internal structure of the karst system is not investigated and considered as a black-box model, which modifies the input signal (rainfall) into an output signal (spring discharge). With the help of hydro chemical analyses on spring water samples and single discharge measurements, it is possible to set specific mass balance models correlating ion content to spring flowrates. In particular, Mg2+ revealed a reliable application for spring baseflow separation in karst settings. Once the local model has been set, its conservative behaviour, in mostly limestone dominant aquifers, allows using it as a natural tracer of groundwater flow, distinguishing conduit flow and diffuse flow occurrence in the spring outlet, without additional discharge measurements. In karst settings, the difficulty in setting a fixed cross-section for continuously monitoring of spring discharge values makes this application interesting for exploitation management.This study shows the results obtained for two springs located in Central Italy, confirming that monitoring groundwater quality in karst environments is often the key to successfully characterize springs and assess the total yield when direct measurements are not frequent.
Is the additional organic carbon stored thanks to alternative cropping systems and organic waste products application predominantly stable at a decadal timescale?
Authors: Kpemoua Tchodjowiè  Israel , Barré Pierre , Houot Sabine , Baudin François , Plessis Cédric , Chenu Claire
Published: February 2023

The implementation of agroecological practices can lead to an additional soil organic carbon (SOC) storage. The carbon sink effect will be more effective, even in the short and medium term, if the additional storage is realized in the form of persistent organic carbon (OC) and not in labile OC. The objective of this study was to evaluate the biogeochemical stability of additionally C stored by agroecological practices. Biogeochemical stability was assessed using particles size and density fractionation and Rock-Eval (RE) thermal analyses with PARTYsoc machine learning model. Samples were collected from the QualiAgro experiment, where organic wastes products (OWPs) including biowaste compost (BIOW), residual municipal solid waste compost (MSW) and farmyard manure (FYM) were applied, and from the La Cage experiment, where conservation (CA) and organic (ORG) agriculture had been established for 20 years. The plots that received the OWPs showed that 60-66% of the additional C was stored in mineral-associated organic matter (MAOM-C) and 29 - 39% in particulate organic matter (POM-C), whereas in CA and ORG, 77 - 84% of the additional C was stored in MAOM-C versus 15 - 23% in POM-C. While leading to additional C stocks of similar sizes, MSW and FYM exhibited higher proportions of the additionally stored C as POM-C (39 and 29% respectively) compared to CA (15%). This suggests a recalcitrance of POM under OWPs management compared to CA. The PARTYSOC model using RE thermal analysis parameters allows to predict the active (30 - 40 years) and stable (>100 years) carbon pools as defined in the AMG model. The results revealed that most, if not all, of the additional C belonged to the active C pool. These findings suggest that although additional SOC is mainly associated with MAOM-C, it is probably not stored in a form with a mean residence time exceeding ~30 years. The agroecological practices implemented in both long-term field experiments have resulted in substantial short-term additional C storage, but this storage will only be maintained at a high level if these storing practices are continued.
Linking Sea Spray, Bioaerosols and Ice-Nucleation Proteins in Arctic Marine Environments
Authors: Castenschiold Christian DF , Mignani Claudia , Christiansen Sigurd , Alsved Malin , Tesson Sylvie , Löndahl Jacob , Bilde Merete , Finster Kai , Šantl-Temkiv Tina
Published: February 2023

Clouds have one of the most profound effects on Earth’s climate, yet they are still responsible for some of the biggest uncertainties in climate models. Cloud formation, radiative properties, thickness and lifetime are tightly interlinked with the presence of atmospheric particles (aerosols) and the formation of ice. Biological aerosols (bioaerosols) such as ice-nucleation proteins (INpro) produced by microorganisms are most efficient catalysts in the formation of ice and can trigger heterogenous freezing between -1°C and -15°C. Several studies have demonstrated that Arctic environments are a source of airborne INpro. Sea spray is one of the major sources of aerosols, which aside of the sea salt contain large amounts of organic material. These are ejected into the atmosphere through the process of wave breaking and bubble bursting of small bubbles, which eject drops from the sea surface microlayer (SML) to the atmosphere. Here, we present results derived from droplet freezing assays and amplicon sequencing combined with quantitative PCR, targeting the 16S rRNA gene from sea and aerosol samples collected along a transect from sub- to high Arctic Greenland (Baffin Bay). We demonstrate a positive correlation between INpro concentration and higher latitudes in sea bulk water (SBW) and SML. Additionally, we try to link specific taxonomic groups from the microbial communities to INpro production. Last, we aim to investigate if partitioning of specific taxonomic groups can be observed from SBW to SML and from SML to the atmosphere. Finally, we performed laboratorial sea-spray experiments simulating turbulent sea conditions. This study has the potential to help closing the current knowledge gap in understanding the partitioning of microorganisms from the sea to the atmosphere and unravel which microbes are the major contributors to atmospheric INpro and hence cloud formation.
Megathrust stress drop as trigger of aftershock seismicity in subduction zone forearcs: Insights from the 2011 Mw 9.0 Tohoku earthquake, Japan
Authors: DIelforder Armin , Bocchini Gian Maria , Kemna Kilian , Hampel Andrea , Harrington Rebecca , Oncken Onno
Published: February 2023

Large megathrust earthquakes like the 2011 Mw 9.0 Tohoku earthquake (Japan) are followed by numerous aftershocks in the subduction zone forearc overlying the seismogenic fault. The aftershocks in the forearc can include normal-faulting events despite the thrust mechanism of the main shock. Postseismic normal faulting has been explained by stress changes induced by the coseismic stress drop along the megathrust. However, details of stress changes in the forearc and aftershock triggering mechanisms remain poorly constrained. Here we use numerical force-balance models combined with Coulomb failure analysis to show that the megathrust stress drop indeed supports normal faulting, but that forearc-wide triggering of aftershocks is feasible within a narrow range of megathrust stress-drop values and forearc stress states only. We determine this range for the Tohoku earthquake and show that the associated stress changes explain the aftershock seismicity in unprecedented detail. In particular, our analysis reveals that ~78% of the aftershocks and ~92% of the seismic moment release occurred in areas where the Tohoku earthquake caused a stress increase, and that the detailed aftershock distribution was also governed by spatial variability in fault strength and forearc topography. Our findings provide new insights into aftershock triggering and help to understand where aftershocks occur after great earthquakes at subduction zones.
Assessment of groundwater quality and piezometric levels using geostatistical methods in Grombalia aquifer, Tunisia.
Authors: Panagiotou Constantinos F. , Akrout Hanene , Baccouche Hatem , Mellah Thuraya , Mansouri Lobna , Ghrabi Ahmed
Published: February 2023

Groundwater sources in arid and semi-arid regions are expected to be gradually more stressed due to multiple causes, such as the depletion of surface water resources, water quality degradation, increasing demand of agriculture and economic and demographic growth.   As a result, there is a need to secure the availability and quality of groundwater reserves in those areas.Large and high-dimensional datasets are required to fully characterize the physico-chemical properties of the complex groundwater processes. Subsequently, statistical tools are used to provide estimations of these properties beyond the sampling locations, which are required in order to provide reliable assessments of the associated risks. Geostatistical tools are widely used in groundwater applications to estimate the spatial variability of quality parameters by combining different types of datasets to build local models of spatial uncertainty. Special attention is given to the kriging method, which provides an estimate of the unknown quality variable value along with a measure of uncertainty regarding that estimate.In the current study, groundwater samples are collected from an unconfined aquifer, located at north-eastern Grombalia (Tunisia). Ordinary kriging is used to estimate the spatial variability of piezometric levels and quality parameters. Sampling data are subjected to suitable transformations prior geostatistical computations so that the Gaussian assumption is satisfied, whereas the results are back-transformed to the original space. Different numbers of neighboring data points are considered to decide the spatial extent of the search neighborhood by comparing cross-validation errors. In addition, indicator kriging is used to construct probability maps of the quality parameters, and identify regions that possess high probability to exceed irrigation water quality standards. AcknowledgementThis work is conducted under ‘EXCELSIOR’ project (www.excelsior2020.eu), which has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 857510, from the Government of the Republic of Cyprus through the Directorate General for the European Programmes, Coordination and Development and the Cyprus University of Technology. This work is also supported by the PRIMA program under grant agreement No1923, project InTheMED. The PRIMA program is supported by the European Union.
Stabilized Criegee Intermediates are important nocturnal oxidants in the summertime air of the Indo-Gangetic Plain.
Authors: Shabin Muhammed , Kumar Ashish , Hakkim Haseeb , Rudich Yinon , Sinha Vinayak
Published: February 2023

Night-time oxidation significantly affects concentrations of both primary and secondary air pollutants but is poorly constrained over South Asia. Here, we investigate the chemistry, formation and abundance of Stabilized Criegee Intermediates (SCI) in the summertime air of the Indo-Gangetic Plain using measurements of its precursors and sinks. This includes ethene, propene, 1-butene, cis-2-butene, trans-2-butene, 1-pentene, cis-2-pentene, trans-2-pentene, and 1-hexene for which this work also reports the first summertime dataset from the IGP. Ethene, propene, and 1-butene were the highest ambient alkenes in both summer and winter. Morning and noon-time concentrations in summer were ~5.6 and ~3.3 times higher relative to winter, suggesting stronger alkene emission sources in summer. Applying chemical steady-state to the measured precursors, the average calculated SCI concentrations were 4.5 (± 3.8) × 103 molecules cm-3, with Z-CH3CHOO (55 %) as the major SCI. SCI production rates drove ambient SCI with Z-RCHOO (35 %) and α-pinene derived PINOO (34 %) as the largest contributors to the SCI production rate of 7.8 × 105 molecules cm-3 s-1. Peak SCI occurred during evenings. All SCI loss was dominated (>70 %) by unimolecular decomposition or reactions with water vapour. Pollution events influenced by crop biomass fires resulted in significantly elevated SCI production (2.1 times higher relative to non-polluted periods) reaching as high as (7.4 ± 2.5) × 105 molecules cm-3 s-1. Among individual SCI species, Z-CH3CHOO was highest in all the plume events with a contribution of at least ~41 % and among alkenes, trans-2-butene was the highest contributor to P(SCI) in plume events with values ranging from 22-32 %. SCIs dominated the night-time oxidation of sulphur dioxide with rates as high as 1.5 (± 1.3) × 104 molecules cm-3 s-1at midnight, suggesting this pathway could be a significant source of fine mode sulphate aerosols over the Indo-Gangetic Plain, especially during summertime pollution episodes.