bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining bioleaching and brine-leaching in metal leaching processes: alternative to conventional
Authors: Azevedo Schueler Tamara , Goldmann Daniel
Published: March 2021

The recovery of valuable metals such as copper (Cu), zinc (Zn) and lead (Pb) from mine tailings has gained attention in recent years, mainly for the environmental risk of tailings storage facilities and the demand of such elements in different industrial sectors. Many sulphide tailings deposits are spread worldwide, and some of them belong to active mines, which produce tons of material per year. Leaching is a well-known technology for metal extraction. However, two aspects must be considered: the dissolution of metals involves the use of fresh water and, the tailings contain low metal concentrations and high impurities. As a result, leaching is too expensive due to energy input in water purification and high acid consumption. The use of salt water in mineral extraction processes is becoming more attractive in the mining sectors over the years, especially in regions where fresh water is scarce. The presence of salt water in metal leaching has demonstrated a great capacity to increase metal extraction from ore, for example, by increasing the surface and porosity of copper containing minerals. This phenomenon plays an important role in metal leaching. The formation of a passive layer on the surface of the mineral in oxidizing conditions is a strong barrier in the extraction of the target metal. Conditions that overcome this obstacle are of utmost importance for the mining industry. Furthermore, a combination of conventional leaching systems with biological methods (bioleaching) is shown to be a good strategy in tailings leaching. Bioleaching has been applied to the treatment of poor ores and tailings, since acidophilic bacteria can oxidize Fe2+ with the regeneration of Fe3+ ions, together with the reduction of sulphur species to sulfuric acid, leading to the extraction of metals. Moreover, it is considered a more environmentally friendly technology than traditional extraction methods, as it occurs naturally, more economical and results in significantly less pollution. Therefore, some studies have been applying biological leaching as a pre-treatment for chemical leaching of mining tailings. The aim of this work is to present and discuss possibilities to conventional metal extraction processes, combining the two strategies of bioleaching and brine-leaching.
Solar wind and bow shock parameters affecting turbulence development inside the magnetosheath
Authors: Rakhmanova Liudmila , Riazantseva Maria , Zastenker Georgy , Yermolaev Yuri
Published: March 2021

Development of the turbulent cascade inside the magnetosheath is known to be affected by the bow shock. Recently a number of studies showed various scenario of turbulent cascade modification at the bow shock including deviation from Kolmogorov scaling and additional damping of the kinetic-scale compressive fluctuations. Also, properties of probability distribution function may be modified behind the bow shock. However, factors which govern turbulence development in the magnetosheath remain unclear. Present study focuses on experimental analysis of the solar wind parameters which influence turbulence inside the magnetosheath. Analyzed data involves the combination of the solar wind parameters measured in L1 point by WIND spacecraft and Themis, Cluster and Spektr-R measurements behind the bow shock. Parameters of the frequency spectra of ion flux and/or magnetic field magnitude at frequency band from 0.01 to 2-10 Hz are considered such as slopes at magnetohydrodynamic and kinetic scales and the break frequency. Parameters of spectra are considered behind the bow shock of various topology i.e. for different mutual orientation of the interplanetary magnetic field and the local bow shock normal. Also, distance from the analyzed point to the bow shock nose is taken to the account. Obtained results point out that modification of the turbulent cascade at the bow shock is controlled not only by the bow shock topology but also by variability of the upstream solar wind plasma parameters and direction of the interplanetary magnetic field. In particular, Kolmogorov scaling often survives across the bow shock during periods of high-amplitude variations of plasma density and magnetic field magnitude in the solar wind. Also, increasing amplitude of northern interplanetary magnetic field results in steepening of spectra behind the bow shock.  
Managing coastal aquifers in climate and socio-economic change: An indicator-based multi-criteria decision system approach
Authors: Langmann Tobias , Schöniger Hans Matthias , Schneider Anke , Sander Michael
Published: March 2021

Worldwide, climate change as well as socio-economic changes are increasing pressure on water supply in coastal regions and lead to major changes in groundwater recharge as well as the regional water balance as parts of the hydrosystem. These changes are threatening water security and, thereby, impede the fulfillment of the SDG 6 targets, esp. SDG targets 6.2., 6.4. and 6.6 of the UN 2030 Agenda for Sustainable Development. Thus, a modern water management demands innovative and profound methods and tools that comprehensively cover these complex changes. To address this challenge,  in the BMBF project "go-CAM" (Implementing strategic development goals in Coastal Aquifer Management) we took the methodological approach of developing new groundwater status indicators (e.g. chloride concentration in groundwater, position of saltwater/freshwater interface, freshwater volume) and corresponding target functions implemented in a new online-based management and evaluation tool called "CAM" (Coastal Aquifer Management). Both the physically based indicators as well as the target functions tackle economic as well as ecological issues. The groundwater status indicators are directly derived from the results of high-resolution, process-based (hydrological and hydrogeological) modeling of coastal hydrosystems. Due to their physical nature, the indicators are only applicable with appropriately designed climate and socio-economic scenarios for coastal water management if they are generated with models that also capture the system-relevant processes: Groundwater recharge, groundwater abstraction, discharge dynamics through drainage systems, sea level rise and groundwater discharge to the sea and saltwater intrusion.

The CAM platform is a tool that provides a way to make the results of the complex and extensive numerical modeling usable for a wider community and thus allow for a more efficient result exploitation. Building on the indicators and the selection of target functions and weighting factors the CAM tool uses Multi-Criteria Decision Analysis techniques (MCDA) to strengthen transparency and objectivity in decision-making processes and encourage communication between decision-makers in the water sector of coastal regions. In this way, the application of the CAM tool contributes to the establishment of an integrated water resources management and to derive and discuss future water management strategies as well as concrete measures.

Our methodological approach as well as the results are presented applied to a regional coastal groundwater study area in the northwestern part of Germany, the Sandelermöns region, which covers an area of about 1,000 km².
The distribution and behavior of mercury in snow
Authors: Mikhailenko Anna , Fedorov Yury , Minkina Tatiana , Dmitrik Leonid , Dotsenko Irina , Solodko Daria , Chepurnaya Viktoria
Published: March 2021

With atmospheric precipitation to 28% of mercury (from their total input into this basin) is transported to the Azov Sea via precipitation [1,2]. There is an increasing tendency in the mercury concentrations in rain and snow sampled in the cities of the Rostov Region, compared to precipitation over the sea and its coast. The maximum mercury concentrations in the hydrometeors were found in the cities in autumn and winter. It is due to its penetration into the troposphere as a result of the rapidly increasing dust amounts and gas emissions sourced by combustion of coal, fuel oil, and gas during the heating season. The mercury concentrations in the hydrometeors are higher in stale snow than in just-fallen snow. It is suggested that stale snow is a depositing material absorbing mercury from the troposphere, where it accumulates due to activity of various enterprises with pollutant emissions. This statement is confirmed indirectly by the fact that the Donbass coals are characterized by high mercury concentrations [1]. Another mechanism could be mercury re-distribution during the compaction of snow cover and its interaction with soil. In the course of the winter expeditions, a clear snow stratification was registered: just-fallen powder and stale crystallized grey snow with a large amount of mineral and organic material. In stale snow, the dissolved and suspended form of mercury migration prevailed over its content in freshly fallen snow. The mercury content in hydrometeors was influenced by such factors as wind activity and the amount of atmospheric precipitation. On the one hand, when wind activity increases, the atmosphere surface layers in the cities are cleared from technological substances, and the input of soil particles increases during dust storms. There is intensive mercury leaching from the atmosphere during torrential rains. It leads to a sharp decrease in its atmospheric concentrations. On the other hand, there is an increase in the mercury content in the rainfall after a dry period under calm weather conditions.

The work was carried out with the financial support of the RF President grant No. MK-1862.2020.5., RFBR projects No. 19-05-50097.

Литература

[1]. Fedorov Yu. A., Mikhailenko V., Dmitrik L. Y., Dotsenko I. V., Solodko D. F., Chepurnaya V. I. Mercury and iron in precipitation of the Azov Sea basin// Limnology and Freshwater Biology, 2020,№1,pp. pp.838-839.

[2]. Klenkin A. A., Korpakova I. G., Pavlenko L. F., Temerdashev Z. A. Ecosystem of the Sea of Azov: anthropogenic pollution. Krasnodar: "Enlightenment-SOUTH", 2007. – 324p.
Silicon isotopes: linking soil Si availability and plant Si strategies
Authors: Delvigne Camille , Keller Catherine , Guihou Abel , Basile-Doelsch Isabelle , Angeletti Bernard , Deschamps Pierre , Meunier Jean-Dominique
Published: March 2021

One of the most puzzling properties of silicon (Si) is its differential absorption by plants. Depending on the plant species, water and soil Si availability, environmental factors such as grazing and temperature, plant Si contents can vary from 0.1 % to 10 %(on a dry weight basis). Advances in genomics improved our understanding of biochemical and molecular mechanisms underlying plant Si uptake providing a framework to explain the variability of Si in plants and its distribution. Yet complex Si roles in plant strategies, its dependence on environmental factors and in mediating interactions with their environments and other organisms remain misunderstood. How is plant Si uptake affected by soil Si availability and how is Si distribution between tissue types controlled? It is hard for us to answer those questions even if Si plant traits are an indicator of the soil Si status. For example, a few studies showed that Si content and phytolith distribution are mainly controlled by Si availability. In this study, a pot experiment was conducted in a greenhouse where wheat (Triticum turgidum L.) was grown on three different soils: an aric podzol, an andosol and a calcosol. These soils are contrasted in term of clay size distribution, SiO2 concentrations and organic matter content and are presumed to reflect French soils variability in term of Si dynamics. Here, we focus on how plant Si patterns, both Si content and Si isotopes, are linked to soil Si availability leading to new insights to the mechanisms underlying the different Si uptake and translocation strategies. This work is supported by the BIOSiSOL project (ANR-14-CE01-0002).
Transient simulations over the Common Era in PMIP4/CMIP6
Authors: Jungclaus Johann , Alastrue de Asenjo Eduardo , Cauquoin Alexandre , Fang Shih-Wei , Khodri Myriam , Lorenz Stephan , Ohgaito Rumi , Sam Teffy , Timmreck Claudia , Toohey Matthew , Werner Martin , Yoshida Kohei , Zanchettin Davide , Zhang Qiong
Published: March 2021

The Common Era (CE, i.e. the two millennia before the industrialization) is among the periods selected by the Paleo Model Intercomparison Project (PMIP) for transient experiments contributing to PMIP4. For PMIP4, novel estimates and updates of external forcing have been compiled (Jungclaus et al., GMD, 2017).  In addition to the Tier-1 category simulation “past1000” for the period 850 CE to 1849 CE, the Tier-3 “past2k” experiment covers the entire CE. After serious delays, the ESGF is now being filled by modeling groups running the transient simulations.

Here we provide an overview of the simulations, discuss the range of applied models, and present first results of common analyses from past1000 and subsequent historical simulations. We discuss the long-term climate evolution, the range of internally-generated and externally-forced variability and specific aspects of the response to volcanic forcing.

Another focus is the presentation of the first MPI-ESM ‘past2k’ simulations and their extension to include water isotopes in MPI-ESM-WISO. These simulations extend the pool of current ESM simulations into the 1st millennium CE and represent an important basis to assess the models’ response to external forcing and improved model-data comparison. We analyze regional trends and variations over the last 2000 years in comparison with PAGES2k reconstructions.

 
Molecular insight into DMSP production in temperate shelf sea waters
Authors: Hopkins Frances E. , Airs Ruth , Polimene Luca , Todd Jonathon
Published: March 2021

Marine dimethyl sulfide (DMS) emissions are an important source of atmospheric sulfate aerosols which exert a strong influence on climate. The major biological precursor for DMS is dimethylsulfoniopropionate (DMSP), an abundant compatible solute produced by many marine eukaryotes and prokaryotes.  Despite the importance of DMSP, knowledge of how, why and by what it is produced is limited. For example, haptophytes (inc. coccolithophores) and dinoflagellates typically produce 50-100 times more DMSP per unit Chlorophyll a than diatoms and prochlorophytes. However, the reasons for this are not fully understood as the relevant enzymes have until recently been poorly characterised. Furthermore, although the DMSP synthesis genes and their transcripts are widespread in surface ocean bacterial communities, the contribution by this group of organisms to total DMSP production is so far unquantified. Here, we present a 6-month time series (April – September 2018) of in-vivo DMSP synthesis rates at an established time series station in temperate shelf sea waters, alongside characterisation of the key S-methylation step of DMSP synthesis pathways. DMSP concentrations ranged from 21 – 165 nM, with peaks in DMSP production rates in late April (26.1 nmol L-1 d-1) and early July (19.1 nmol L-1 d-1). These DMSP production peaks coincided with significant increases in the abundance of known DMSP producing algae and bacteria, and of their transcription of DSYB/dsyb genes, as indicated by RT-qPCR and ‘omics analysis.  These novel state and rate data, have been used to refine a DMS dynamics model by including newly defined DMSP-specific functional types, including both algal and bacterial DMSP producers.
Spatio-temporal variations of climate variables and extreme indices over Iran during 1986-2015 
Authors: Malaekeh SayedMorteza , Safaie Ammar , Shiva Layla
Published: March 2021

In order to better understand how climate changes have taken place in Iran, we carried out a comprehensive analysis of the spatio-temporal trends of various climate variables and extreme indices during 1986 to 2015 at the county-level across the country. Additionally, the interannual oscillation of the temperature and precipitation and their related extreme indices were examined throughout the research. In this study, ERA5-Land and AgrERA5 datasets with hourly, daily, and monthly temporal resolutions were aggregated to the county-level to calculate climate extreme indices. Subsequently, different approaches such as the original Mann-Kendall (MK) trend test, MK with block bootstrap modification, MK with variance correction modification, correlated seasonal MK (partial MK), original and seasonal Sen's Slope were implemented to detect the magnitude and the statistical significance of climatic trends for each county. Finally, the continuous wavelet transform was employed for whole country averages to investigate fluctuations and dominant periods of the variables and indices. The reanalysis model datasets offered us two advantages; firstly, it facilitates obtaining data in some regions with sparse weather stations and secondly, it allows us to inquire about some climate variables that were less studied in the literature, for instance, the wind speed, the surface air pressure, the solar radiation, the surface albedo, the runoff, the evaporation, and the skin reservoir content. The results showed a significant increasing trend in the temperature over all counties and a nonsignificant drying trend in the precipitation for almost the whole country. Other climate variables demonstrated more mixed spatio-temporal trends; however, generally, the wind speed and the solar radiation had an upward trend, the runoff, the skin reservoir content, and the surface albedo showed a downward trend, while the surface air pressure and the evaporation trends exhibited a great deal of variety. Furthermore, the hot climate extremes were increased throughout the country whereas the cold extremes and the extreme precipitations were quite in the opposite direction. It is noteworthy that the Continental and the Warm-Temperate climates were more vulnerable compare to the Arid and Semi-Arid Climates. At last, the wavelet power spectrum maps indicated the consistency between the temperature and precipitation and their related extremes and also showed a reduction in the fluctuation of the precipitation and a constant oscillation for temperature over the study period.
Towards psychological herd immunity: Cross-cultural evidence for two prebunking interventions against COVID-19 misinformation
Authors: Roozenbeek Jon , Dryhurst Sarah
Published: March 2021

Misinformation about the novel coronavirus (COVID-19) is a pressing societal challenge. Across two studies, one preregistered (n = 1,771 and n = 1,777), we assess the efficacy of two “prebunking” interventions aimed at improving people’s ability to spot manipulation techniques commonly used in COVID-19 misinformation, across three different cultural contexts (English, French, and German). We find that Go Viral!, a novel 5-minute “prebunking” browser game, (a) increases the perceived manipulativeness of misinformation about COVID-19, (b) improves people’s confidence in their ability to spot misinformation, and (c) reduces self-reported willingness to share misinformation with others. The first two effects remain significant for at least one week after gameplay. We also find that reading real-world infographics from UNESCO improve people’s ability and confidence in spotting COVID-19 misinformation (albeit with a smaller effect size than the game). 
Impact of bias correction techniques on an ensemble of seasonal discharge forecast for the Danube upstream of Vienna
Authors: Martin Santos Ignacio , Herrnegger Mathew , Holzmann Hubert
Published: March 2021

The skill of seasonal hydro-meteorological forecasts with a lead time of up to six months is currently limited, since they frequently exhibit random but also systematic errors. Bias correction algorithms can be applied and provide an effective approach in removing historical biases relative to observations. Systematic errors in hydrology model outputs can be consequence of different sources: i) errors in meteorological data used as input data, ii) errors in the hydrological model response to climate forcings, iii) unknown/unobservable internal states and iv) errors in the model parameterizations, also due to unresolved subgrid scale variability.

Normally, bias correction techniques are used to correct meteorological, e.g. precipitation data, provided by climate models. Only few studies are available applying these techniques to hydrological model outputs. Standard bias correction techniques used in literature can be classified into scaling-, and distributional-based methods. The former consists of using multiplicative or additive scaling factors to correct the modeled simulations, while the later methods are quantile mapping techniques that fit the distribution of the simulation to fit to the observations. In this study, the impact of different bias correction techniques on the seasonal discharge forecasts skill is assessed.

As a case study, a seasonal discharge forecasting system developed for the Danube basin upstream of Vienna, is used. The studied basin covers an area of around 100 000 km2 and is subdivided in 65 subbasins, 55 of them gauged with a long historical record of observed discharge. The forecast system uses the calibrated hydrological model, COSERO, which is fed with an ensemble of seasonal temperature and precipitation forecasts. The output of the model provides an ensemble of seasonal discharge forecasts for each of the (gauged) subbasins. Seasonal meteorological forecasts for the past (hindcast), together with historical discharge observations, allow to assess the quality of the seasonal discharge forecasting system, also including the effects of different bias correction methods. The corrections applied to the discharge simulations allow to eliminate potential systematic errors between the modeled and observed values.

Our findings generally suggest that the quality of the seasonal forecasts improve when applying bias correction. Compared to simpler methods, which use additive or multiplicative scaling factors, quantile mapping techniques tend to be more appropriate in removing errors in the ensemble seasonal forecasts.
Three-dimensional reconstruction of an expanding shock associated with a Solar particle event
Authors: Frassati Federica , Laurenza Monica , Bemporad Alessandro , West Matthew J. , Mancuso Salvatore , Susino Roberto , Alberti Tommaso , Romano Paolo
Published: March 2021

On 2013 June 21st an eruption occurred in the active region NOAA 1177 (14S73E), giving rise to a M2.9 class flare starting at 02:30 UT, a fast partial halo coronal mass ejection (CME), and a type II radio burst. The concomitant emission of solar energetic particles (SEPs) produced a significant increase in the proton fluxes measured by LET and HET aboard STEREO-B. By using stereoscopic observations in extreme ultra violet (EUV) and white light (WL) spectral intervals, we performed a 3D reconstruction of the expanding front by processing SDO/AIA, STEREO/EUVI, COR1 and COR2, and SOHO/LASCO data assuming a spheroidal model. By using the 3D reconstruction, we estimated the temporal evolution of θBn, i.e., the angle between the normal to the expanding front and the coronal magnetic field computed by the Potential-Field Source-Surface (PFSS) approximation, within 2.5 Rʘ. The front of the CMEwas found to be quasi-parallel to the magnetic field almost everywhere. Above 2.5 Rʘ, where the front was identified as a shock, we projected the 3D expanding surface reconstructed for different times on the ecliptic plane and we calculated the θBn between the normal to the front and Parker spiral arms. In this case the shock was almost perpendicular to the magnetic field (quasi-parallel shock). During the expansion the region located between the nose and the eastern flank of the shock was magnetically connected with ST-B in agreement with the significant SEP flux measured on-board this spacecraft. While the shock was only marginally connected with ST-A and GOES-15. The SEP release time was estimated to be 10 minutes after the Type II onset, when the shock front was already above 2.5 Rʘ with a quasi-parallel configuration. Our results are discussed in the framework of the shock acceleration scenario, even if quasi-parallel shocks are expected to have a reduced acceleration efficiency.
The anthropogenic environmental impacts and changes in the tropical Atlantic - a high resolution Cuban coral time series over 154 years
Authors: Harbott Marie , Wu Henry , Kuhnert Henning , Kasemann Simone , Meixner Anette , Jimenez Carlos , González-Diáz Patricia , Rixen Tim
Published: March 2021

Changes in the surface ocean pH and temperature caused by the uptake of anthropogenic CO2 are posing a threat to calcifying marine organisms. Recent studies have observed significant impacts on coral reef ecosystems with impaired carbonate skeletal growth and decreased calcification due to acidifying oceans. In situ measurements from buoys, ships, and remote observations by satellite of sea surface temperature, salinity, and ocean’s carbonate chemistry are sparse and only date back a few decades. The current coverage of observations for the northwestern Cuban coastal waters provides hence an incomplete picture of natural climate variability over interannual to interdecadal timescales, showing the need for high resolution climate archives.

Cuba is situated between densely populated landmasses of North and South America offering a unique environment to study multiple aspects of anthropogenic activity across the region as well as their interconnectivity.

A massive coral, Siderastrea siderea, from Cuba’s northwestern coast, was used as a natural archive to reconstruct bimonthly changes in SST, and carbonate chemistry through a multi-proxy approach since preindustrial times.

Preliminary results indicate a decrease in δ18O of 0.32 ‰ over 154 years since 1852,  indicating warming and/or freshening of the surface water over this period. Over the same time period, the δ11B ratio decreased by ca. 1.6 ‰, translating into a decrease of 0.1 on the pH scale, reflecting the acidification of the northwestern Cuban coastal waters. Furthermore, an accelerating decrease of coral δ13C from the 1850s to 2005 of 1.5 ‰ demonstrates the anthropogenic imprint due to increased fossil fuel combustion. Further investigation and the comparison to trace elements indicate possible baseline shifts in regional seawater carbonate chemistry that have been affected by anthropogenic activity.
Seasonal forecast skill of windstorm frequency and intensity over Europe and their dynamical and physical reasons
Authors: Degenhardt Lisa , Leckebusch Gregor C. , Scaife Adam A.
Published: March 2021

The seasonal forecast of extreme events is gaining more and more interest in science, for stakeholders and the general public. The most important extreme events with a seasonal variance for Europe, including the British Isles, are winter windstorms.

This study is investigating the prediction of seasonal accumulated storm frequency and intensity based on one state-of-the-art seasonal forecast model, the UK Met Office (GloSea5 GC2) and analyses the dynamical and physical reasons for skill.

Winter (DJF) windstorm events are individually identified and tracked using 10m wind speed once exceeding the local 98th percentile. The intensity of the season is calculated via an integrated measure based on the Storm Severity Index (Leckebusch et al., 2008).  Thus, the total seasonal intensity is investigated as grid cell accumulated index over all storm events and as storm count normalised sum. The forecast skill is assessed via different skill measures (e.g. Kendall-Correlation or RPSS) and validated in a hindcast approach with ERA5 for 23 seasons (1993-2015).

This presentation will give an overview about three main topic areas: the prediction skill for storm frequency and intensity; a multi-linear regression analysis to identify dominant large-scale modes, and finally, an outlook on first results on chosen dynamical parameters influencing the skill.

This investigation shows significant positive correlations over the British Isles for all three different storm parameters (frequency and both intensity measures). The positive skill pattern of the storm intensity is shifted north-west-wards compared to the positive skill in the storm frequency results. The accumulated intensity shows slightly higher correlations as the storm frequency. The normalised intensity reveals the lowest skills but still significant values downstream of the British Isles. Hence, three different storm parameters show positive prediction over UK; pure frequency, pure intensity and a combined measure of intensity and frequency.

Additionally to the model skill investigation, a regression analysis based on the three dominant teleconnection patterns over Europe (NAO, SCA and EA) was performed in order to gain better understanding in the connection of storms and these modes. This regression predicts the three storm parameters out of the given indices and explains up to 40-50% of variance. A statistical-model based approach of the storm parameters using three large-scale modes is showing improvements in skill compared to previous studies with NAO as only predictor. But the forecast model output shows still the best storm predictions.

Further studies will investigate the dynamical and physical reasons of the skill and their connections between the windstorm parameters, the dominant large-scale modes, and other atmospheric parameters.
Passive acoustic emissions: a dynamic tool to monitor soil structure variations?
Authors: Lacoste Marine , Giot Guillaume , Seger Maud , Cousin Isabelle
Published: March 2021

The structure of soils, i.e. the macroscopic organization of aggregates and pores, conditions the storage and transport of water and gas in the soil, and strongly determines the physico-chemical environment of soil organisms (plants, micro and macro-organisms). The description of the soils structure dynamics constitutes a major issue in the current context of global change, at the scientific, environmental and agronomic level. However, few tools are available to monitor this dynamic non-destructively and in situ. We therefore propose to develop a new method based on the analysis of acoustic emissions (AE) spontaneously emitted by soils during the evolution of their structure. A laboratory feasibility study was conducted to explore the links between variations in soil structure and the AE emitted during soil desiccation.

Two undisturbed soil columns (8 cm in diameter, 5 cm high) were sampled in an agricultural field (near Chartres in France), in the surface horizon of a Glossic Retisol. These cylinders were air dried (20°C during 9 days), and the AE produced during drying were monitored using piezoelectric sensors place at the soil surface. The concomitant soil structure changes were followed through 3D images, acquired by X-ray tomography (CIRE platform, INRAE, Nouzilly) all along the experiment. These images, with a resolution of 168 µm, were used to characterize the pore network (porosity, surface density, connectivity, etc.).

The dynamics of the EAs recorded during the drying of the samples is comparable for the two samples: the AE rates are maximum at the start of the experiment and then reach a plateau. Changes in soil structure follow the same dynamics, e.g. considering porosity or surface density of the pores. If we analyze the relationship between the signals recorded by the surface sensors (EA rate) and the porosity, we observe a linear relationship (R² of 0.79). This relationship, although encouraging, remains to be consolidated by additional results.

To go further, it is also necessary to define the necessary conditions to perform such a measurement in situ, and to improve the acoustic signal processing to characterize the EA produced during soil desiccation. Indeed, a major objective of our work is to differentiate, thanks to EAs, the various factors responsible for the evolution of soil structure (physical and biological), by determining their "acoustic signature".
A global meta-analysis reveals a significant offset in δ2H between plant water and its sources
Authors: de la Casa Javier , Barbeta Adrià , Rodriguez-Uña Asun , Wingate Lisa , Ogeé Jérôme , Gimeno Teresa E.
Published: March 2021

 

Long-standing ecological theory establishes that the isotopic composition of the plant water reflects that of the root-accessed sources, at least in non-saline or non-xeric environments. However, a growing number of studies challenge this assumption by reporting plant-source offsets in water isotopic composition, for a wide range of ecosystems. We conducted a global meta-analysis to systematically quantify the magnitude of this plant-source offset in water isotopic composition and its potential explanatory factors. We compiled 108 studies reporting dual water isotopic composition (δ2H and δ18O) of plant and source water. From these studies, we extracted the δ2H and δ18O of both plant and source waters for 223 plant species from artic to tropical biomes. For each species and sampling campaign, within each study, we calculated the mean line conditioned excess (LC-excess), with the slope and intercept of the local meteoric water line, and the mean soil water line conditioned excess (SWL-excess), from the slope and intercept of the soil water evaporation line. For each study site and sampling campaign, we obtained land surface temperature and volumetric soil water from the ERA5 database. For each study species, we recorded the functional type, leaf habit and for those available wood density. We found, on average, a significantly negative SWL-excess: plant water was systematically more depleted in δ2H than soil water. In > 90% of the cases with significantly negative SWL-excess, we also found negative LC-excess values, meaning that access to sources alternative to soil water was unlikely to explain negative SWL-excess values. 

Calculated SWL-excess was affected by temperature and humidity: there were larger mismatches between plant and source water in isotopic composition in colder and wetter sites. Angiosperms, broadleaved and deciduous species exhibited more negative SWL-excess values than gymnosperms, narrow-leaved and evergreen species. Our results suggest that when using the dual isotopic approach, potential biases in the adscription of plant water sources are more likely in broadleaved forests in humid, and cold regions. Potential underlying mechanism for these isotopic mismatches will be discussed.

 
Quantifying sensitivity and exposure of multiple ecosystem services to climate change: A case study of the Qinghai-Tibet Plateau 
Authors: Hua Ting , Zhao Wenwu , Pereira Paulo
Published: March 2021

        Global warming has imposed a positive or adverse impact on ecosystem services and it will be further amplified in vulnerable areas like Qinghai-Tibet Plateau. However, there is a limited understanding of spatial interaction among ecosystem services and their climatic drivers at a fine resolution, regardless of the historical or future periods. This study attempted to fill this gap by detecting sensitivity and exposure of ecosystem services to climate change based on spatial moving window method, combined with Modis-based satellite datasets and various future scenarios dataset. We found that Carbon Sequence and Oxygen Production (CSOP) and habitat quality experienced significant growth, while water retention (WR) showed a fluctuation trend on the Qinghai-Tibet Plateau. For CSOP, 56.94% of the pixels showed a positive sensitivity to climate change, which is nearly twice the ones with negative sensitivity (26.72%). And there is an evident positive sensitivity between WR and precipitation. Also, there is substantial spatial heterogeneity in the exposure of ecosystem services to future climate changes. A high-emission pathway (SSP5-8.5) increases the intensity of exposure on ecosystem services than low-emission pathway, and disturbances accompanied by future climate change at specific elevation intervals should not be ignored. Identifying spatial association among the ecosystem services and climatic drivers is helpful for targeted management and sustainable development of soil in the context of global warming.

Keywords

Ecosystem services, Climate change, Qinghai-Tibet Plateau, Sensitivity, Exposure
Simulation of a small scale model of dike susceptible to suffusion
Authors: Gelet Rachel , Kodieh Alaa , Marot Didier
Published: March 2021

Suffusion is characterized by a migration of the fine particles within a given volume of soil under the effect of flow. This complex phenomenon involves simultaneous detachment, transport and possible filtration of the fine fraction. With the objective to reproduce the amplitude and the kinetics of the suffusion process within a small scale model of dike, a poro-elastic model accounting for suffusion is implemented in a FEM code. The rate of eroded mass is modeled by a constitutive relation named the energy-based law [1], which is inspired from the energy-based approach [2]. This relationship uses two key parameters that describes the end of the suffusion process: the erosion resistance index and the maximum cumulative expended volumetric energy. An additional parameter named the smoothing time, which controls the kinetics of the suffusion process, is used to account for the history of the power dissipated by the flow. These three parameters are calibrated on a first specimen which was experimentally suffused up to a stable state of erodibility.

Next, a small scale model of dike is simulated using the poro-elastic model extended to suffusion. This dike model, which was experimentally tested by Rochim [3], is assumed to be initially homogeneous and characterized by an isotropic permeability. To illustrate the capability of the energy-based relationship in tackling the suffusion process, the FEM results using the energy-based relationship are compared with the experimental measurements. The dike behavior is investigated in terms of downstream flow rate, total water head at specific pressure ports, cumulative eroded mass and post-suffusion spatial distribution of the percentage of fines. The energy-based approach is able to predict the total amount of cumulative eroded mass, the correct magnitude of the percentage of fines variation and a smoother version of the spatial distribution of the fine particles at the end of the suffusion process.

REFERENCES

[1] Kodieh, A., Gelet, R., Marot, D., & Fino, A. Z. (2020). A study of suffusion kinetics inspired from experimental data: comparison of three different approaches. Acta Geotechnica, 1-19.

[2] Marot, D., Le, V. D., Garnier, J., Thorel, L. and Audrain, P., 2012. Study of scale effect in an internal erosion mechanism: centrifuge model and energy analysis. European Journal of Environmental and Civil Engineering, 16(11), 1-19.

[3] Rochim A., Characterization of suffusion susceptibility of granular soils. PhD thesis, Université de Nantes, 2015.
Northern hemispheric biome changes synthesized from taxonomically harmonized and temporally standardized fossil pollen record since the Last Glacial Maximum in comparison to MPI-ESM simulations
Authors: Li Chenzhi , Dallmeyer Anne , Böhmer Thomas , Postl Alexander , Herzschuh Ulrike
Published: March 2021

Fossil pollen datasets can help to understand the temporal and spatial distribution patterns and driving forces of the past terrestrial biomes in high northern latitudes. Here we present a global pollen dataset since the Last Glacial Maximum, synthesized from 2821 palynological records from the Neotoma Paleoecology Database and additional literature. All terrestrial pollen taxa were taxonomically harmonized on genus (woody taxa) or family level (herb taxa) and temporally standardized by using a defined parameter setting for Bayesian age-depth modeling based on 14C dating. The age-depth models were statistically compared with existing models for each record. With a biomization approach, we reconstructed biomes for several time-slices throughout the last 22000 years with a temporal resolution of roughly 500 years. The reconstructed biome distributions are compared to simulated biome distributions inferred from a transient simulation for the last 25000 years, performed in the comprehensive Earth System Model of the Max Planck Institute (MPI-ESM). The overall biome trend agrees well, but the simulation shows lower forest cover in the high northern latitudes and reaches the maximum forest cover in the Holocene much earlier than the reconstructions indicate.
Airborne in situ tracer and age of air observations in the UTLS during the rare Antarctic sudden stratospheric warming 2019
Authors: Rau Andrea , Lauther Valentin , Hader Fridolin , Cvetkova Svetlana , Volk C. Michael , Hoor Peter , Bense Vera , Bozem Heiko
Published: March 2021

In September 2019 a rare sudden stratospheric warming occurred in the Antarctic region. During the course of this event the airborne campaign SouthTRAC (Transport and composition of the Southern Hemisphere UTLS) was conducted with the main goal of studying the impact of the Antarctic vortex on the southern hemisphere upper troposphere / lower stratosphere (UTLS). SouthTRAC deployed the German High Altitude and LOng range research aircraft (HALO) in two phases (September/early October and November) based in Rio Grande, Argentina. The mission comprised 23 scientific flights including transfer flights to/from Argentina and local flights from Rio Grande. During several of these flights HALO flew over the Antarctic Peninsula and adjacent regions, thus probing the bottom of the Antarctic vortex, and crossing vortex streamers and thin filaments.

We present and analyse in situ measurements of CO2 and various other long-lived tracers obtained by the University of Wuppertal’s 5-channel High Altitude Gas AnalyzeR (HAGAR-V) along with N2O measured by the University of Mainz's UMAQS (University of Mainz Airborne QCL Spectrometer) using laser absorption techniques. For our analysis we use mixing ratios of CO2, SF6, CFC-11, CFC-12, N2O, and age of air (AoA) derived from CO2 and SF6.

Vertical and meridional distributions as well as tracer correlations show differences between phase 1 and phase 2 of the mission. During September the distributions at mid-latitudes indicate stronger isentropic transport of vortex and subtropical air than during November. The CO2-N2O correlation also changed between September and November due to isentropic mixing at 330-400 K potential temperature. The oldest observed AoA as derived from CO2 was about 4.5 years at 390 K, while significantly older AoA is derived from SF6, but is presumably an overestimate due to mesospheric loss of SF6. We have compared the tracer distributions and AoA during SouthTRAC with those of the undisturbed 1999 Antarctic vortex sampled by the M55 Geophysica aircraft during the Antarctic campaign APE-GAIA. For September/October we find similar distributions and age values in both years, which would suggest that net tracer descent trough isentropes in the disturbed 2019 lower Antarctic vortex was not substantially different from that occurring in a typical undisturbed winter.
Strong effect of relative humidity on dryland lichens under climate change
Authors: Porada Philipp , Baldauf Selina , Raggio Jose , Maestre Fernando , Tietjen Britta
Published: March 2021

Manipulative experiments typically show a decrease in dryland biocrust cover and altered species composition under climate change. Biocrust-forming lichens, such as the globally distributed Diploschistes diacapsis, are particularly affected and show a decrease in cover with simulated climate change. However, the underlying mechanisms are not fully understood, and long-term interacting effects of different drivers are largely unknown due to the short-term nature of the experimental studies conducted so far. We addressed this gap and successfully parameterised a process-based model for D. diacapsis to quantify how changing atmospheric CO2 , temperature, rainfall amount and relative humidity affect its photosynthetic activity and cover. We also mimicked a long-term manipulative climate change experiment to understand the mechanisms underlying observed patterns in the field. The model reproduced observed experimental findings: warming reduced lichen cover, whereas less rainfall had no effect on lichen performance. This warming effect was caused by the associated decrease in relative humidity and non-rainfall water inputs, which are major water sources for biocrust-forming lichens. Warming alone, however, increased cover because higher temperatures promoted photosynthesis during early morning hours with high lichen activity. When combined, climate variables showed non-additive effects on lichen cover, and effects of increased CO2 levelled off with decreasing levels of relative humidity. Our results show that a decrease in relative humidity, rather than an increase in temperature, may be the key factor for the survival of the lichen D. diacapsis under climate change and that effects of increased CO2 levels might be offset by a reduction in non-rainfall water inputs in the future. Because of a global trend towards warmer and drier air and the widespread global distribution of D. diacapsis, this will affect lichen-dominated dryland biocrust communities and their role in regulating ecosystem functions worldwide.
Using AE based Machine Learning Approaches to Forecast Rupture during Rock Deformation Laboratory Experiments
Authors: Vinciguerra Sergio , King Thomas , Benson Philip
Published: March 2021

The ability to detect precursors of dynamic failure in brittle rocks has key implications for hazard forecasting at the field scale. In recent years, laboratory scale rock deformation experiments are providing a wealth of information on the physics of the fracture process ranging from fracture nucleation, crack growth and damage accumulation, to crack coalescence and strain localization. Parametric analysis of laboratory Acoustic Emission (AE) data has revealed periodic trends and precursory behaviour of the rupture source mechanisms as a fault zone enucleates and develops, suggesting these processes are somehow repeatable and forecastable. However, due to the inherent anisotropy of rock media and the range of environmental conditions in which deformation occurs, finding full consistency between AE datasets and a prediction of rupture mechanisms from AE analysis is still an open goal. Here we apply a Time Delay Neural Network (TDNN) to Acoustic Emission (AE) sets recorded during conventional triaxial rock deformation tests. We forecast the Time-to-Failure using the discrete, non-continuous timeseries of AE rate, amplitude, focal mechanism and forward scattering properties. 4x10 cm samples of Alzo granite, a homogeneous medium-grained plutonic rock from NW Italy with an initial porosity as low as 0.72%, were triaxially deformed at strain rates of 3.6mm/hr under dry conditions until dynamic failure at confining pressures of 5, 10, 20 and 40 MPa respectively. Each sample was positioned inside an engineered rubber jacket fitted with ports where an array of twelve 1 MHz single-component Piezo-Electric Transducers were embedded, allowing to record AE during the experimentation. Several parameters were considered for the TDNN training: AE rate, deformation stages prior failure (elasticity, inelasticity and coalescence), AE amplitude, source mechanisms and scattering. All these parameters are key indicators of the evolving damage in the medium. Our training input consists of simplified timeseries of the previously discussed AE parameters from the experiments carried out at the lowest confining pressure (5 MPa). The inputs are classified as the stress-until failure and strain-until-failure for each AE. Once trained we then simulate the model on the untrained datasets to test it as a forecasting tool at higher confinements. At each step the model is simulated on AE data from the previous 0.2% of strain. At 10 MPa we observe a reliable forecast of failure that starts with the anelastic phase and becomes more accurate during strain-softening. At higher confining pressure, an increased limit of forecasting the solution is observed and interpreted with more complexity in the coalescence process. Despite these limitations, the model shows that when trained even on a limited input it is able to forecast dynamic failure in unseen data with surprising accuracy. Future studies should investigate AE spatial distribution for the TDNN training.