bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of different land uses on soils organic matter composition from North Eastern part of Romania based on DRIFT spectra
Authors: Bobric Elena Diana , Melniciuc Puica Nicoleta , Breabăn Iuliana Gabriela
Published: March 2022

This study addresses a topical issue, which is a particularly important indicator in assessing the evolutionary trends of the global climate system, namely the storage of carbon in the soil in the form of organic matter. The aim of the research is to estimate and characterize the organic matter from soils with different types of uses and depths located in the North-East Region of Romania, which occupies an area of 36,850 km², characterized by a special natural complexity that has undergone recent structural changes. Soil samples from organic and mineral horizons located at different depths were analyzed. The influence of different land use on the content and chemical composition of organic matter in soils in a topsoil located on the North South was analyzed. The analysis includes a number of 200 soil samples collected from seven different sites (Humor, Pipirig, Vanatori, Tg Neamt, Timisesti, Raducaneni and Munteni) including forest, pastures, arable land, orchards, whether or not subject to specific traditional amendments. Quantitative determination was performed by dry combustion using the combination of equipment: Analytik Jena multi N / C 2100 analyzer and HT 1300 solids module, while for the chemical composition of organic matter the Fourier transform infrared spectroscopy is used (Vertex 70 Bruker), using DRIFT as a sample preparation technique. The amount and chemical composition of organic matter, as well as the location and properties of the soil, have had a strong influence on DRIFT spectra, which are sensitive to the degree of decomposition of organic matter. Differences in absorbance intensity for several spectral bands indicated a higher abundance of recent residues, phenolic-OH, aliphatic and carbohydrate compounds in soils under agricultural use compared to the dominant presence of amide and aromatic groups, carboxylic acids and their salts, C = C bonds in forest soils occupied by deciduous, mixed or coniferous vegetation. Drift spectra have been associated with a number of physicochemical attributes of the soil, such as land cover type, parent material, depth and bulk density, pH, texture, etc. The main conclusion from the regional study indicates that the information recorded in the DRIFT spectra of soils combines the amount and chemical composition of soil organic matter with soil properties highlighting the potential use of this information to assess the state of organic matter degradation stored in the soils of the North East region of Romania.

Keywords: soil organic matter, FTIR, functional groups, Romania, soil composition

"This work was supported by a grant of the "Alexandru Ioan Cuza" University of Iasi, within the Research Grants program, Grant UAIC, code GI-UAIC-2021-12".
Slow slip events captured by GNSS  along the Central Section of the North Anatolian Fault
Authors: Jara Jorge , Ozdemir Alpay , Dogan Ugur , Jolivet Romain , Çakir Ziyadin , Ergintav Semih
Published: March 2022

Recent observations suggest that seismogenic faults release elastic energy not only during sudden earthquakes but also aseismically. Slow slip can be persistent, lasting for years, or episodic. Aseismic slip is thought to be influenced by the presence/migration of fluids, stress interactions through fault geometrical complexities, or fault material heterogeneities. However, slow slip events have mostly been captured by regional GNSS networks in subduction zones, and the finest details of the nucleation, propagation, and arrest of such events have not been observed yet. Therefore, continental creeping faults are ideal targets for tackling such observational gaps and focusing on the sub-daily behavior of such slow slip events.

 

The central segment of the North Anatolian Fault is known to be creeping at least since the 1950s. This region was struck by the Mw 7.3 Bolu/Gerede earthquake in 1944, and since then, no earthquake of magnitude greater than 6 has been recorded. During the 1960s, aseismic slip was discovered as a wall built across the fault in 1957 was being slowly offset. Geodetic studies (InSAR, GNSS, and creepmeters) focused on capturing and analyzing aseismic slip around the village of Ismetpasa. Creepmeter measurements during the 1980s and 2010s, along with InSAR time series analysis, suggest that aseismic slip occurs episodically rather than persistently. However, no permanent GNSS stations were available close enough to the fault to study the details of such slow slip events.

 

Within the scope of a French-Turkish collaboration, we installed 17 GNSS stations (ISMENET) in 2019 to survey the spatio-temporal evolution of aseismic slip rate and characterize the physical properties of the fault zone. A creepmeter array located in the Ismetpasa village reported the occurrence of a significant slow slip event between December 2019 - January 2020. We analyze the GNSS record to search for small aseismic slip episodes and describe their behavior. We use a combination of Multivariate Singular Spectrum Analysis (MSSA) and Geodetic Template Matching (GTM) to extract the signature of aseismic slip and characterize its source. Results are compared to creepmeter measurements, as well as the historical earthquakes, fault geometrical complexities, and kinematic coupling. Our results confirm that aseismic slip in the region is not permanent. Therefore, even though the aseismic slip rate in the long-term seems to be constant, such a rate might result from the contribution of many aseismic slip episodes as the one detected in this work.
Non-invasive isotope-based hydrodynamic imaging in plant roots at cellular resolution
Authors: Couvreur Valentin , Pascut Flavius C , Dietrich Daniela , Leftley Nicky , Reyt Guilhem , Boursiac Yann , Calvo-Polanco Monica , Casimiro Ilda , Maurel Christophe , Salt David E , Draye Xavier , Wells Darren M , Bennett Malcolm J , Webb Kevin F
Published: March 2022

A key impediment to studying water-related mechanisms in plants is the inability to noninvasively image water fluxes in cells at high temporal and spatial resolution. Here, we report that Raman microspectroscopy, complemented by hydrodynamic modelling, can achieve this goal - monitoring deuterated water fluxes within living root tissues at cell- and sub-second-scale resolutions. Raman imaging of water-transporting xylem vessels in Arabidopsis thaliana mutant roots reveals faster xylem water transport in endodermal diffusion barrier mutants. Furthermore, transverse line scans across the root suggest water transported via the root xylem does not re-enter outer root tissues nor the surrounding soil when en-route to shoot tissues if endodermal diffusion barriers are intact, thereby separating ‘two water worlds’ inside roots.
Collective movement by soil bacteria during the colonisation of the rhizosphere
Authors: Engelhardt Ilonka , Patko Daniel , Liu Yangminhao , Mimault Matthias , de las Heras Martinez Gloria , George Tim , MacDonald Michael , Ptashnyk Maryia , Stanley-Wall Nicola , Holden Nicola , Daniell Tim , Dupuy Lionel
Published: March 2022

Migrations are essential for soil microorganisms to exploit scarce and heterogeneously distributed resources in the rhizosphere, but mobility in soil remains poorly studied due to experimental limitations. In this study, time-lapse images collected using live microscopy techniques captured collective and coordinated groups of B. subtilis cells exhibiting “crowd movement” during rhizosphere colonisation. Groups of B. subtilis cells moved through transparent soil toward plant roots and re-arranged dynamically around root tips in the form of elongating and retracting “flocks” resembling collective behaviour usually associated with higher organisms (e.g., bird flocks or fish schools). These B. subtilis flocks are likely driven by the diffusion of extracellular signalling molecules (e.g., chemotaxis and quorum sensing) and may be impacted by the physical properties of the environment. Our findings advance the understanding of bacterial migration through soil matrices and expand known behaviours for coordinated bacterial movement.

 
Testing global geomorphological model as site proxy to predict ground-shaking amplification
Authors: Loviknes Karina , Cotton Fabrice
Published: March 2022

Estimating site amplification of earthquake ground shaking at new sites and sites without any direct geotechnical measurements of site parameters remains a large challenge in seismic hazard assessment. Currently, the standard procedure is to use site proxies inferred from topographic slope from digital elevation models (DEMs). In this study, we test a geomorphological model for inferred regolith, soil and sediment depth by Pelletier et al. (2016). This model was originally developed as input for hydrology and ecosystem models and is based on several global values in addition to the topographic slope, including geological maps and water table data.

To test the suitability of the geomorphological model for ground-shaking prediction we derive the empirical site amplification for sites in Japan, Italy and California using different regional and global seismological datasets. We use the observed shaking amplification to test the correlation between the observed ground-shaking site amplification and the inferred site proxies and test the performance of site amplification models based on geomorphological proxies. We find that the geomorphological model works equally well or slightly better than the traditional inferred proxies. We therefore argue that this model is a promising alternative proxy that can be used for predicting site amplification on new sites and regions for which no geotechnical information exists (i.e. on a global level). This result has important implications for the development of the new generation of ground-shaking models used for shake maps and seismic hazard models.
Analyzing Input Data Influence in Local Techno-Economic Analyses for Power-to-Methane Plants
Authors: Valdes Javier , Bauer Robert , Klaus Grégoire
Published: March 2022

Power-to-methane has been identified as a solution for quickly and effectively exploiting surplus electricity potential. Nevertheless, due to the current efficiencies, costs and sizes, it may not be suitable for local energy transitions. This article presents the results of two optimization models developed in Calliope for two case studies regions, with low wind levels in southern Germany with different electricity mixes. The optimization models simulate all available generation sources in the regions and their extensions with an additional Power-to-methane plant. The model minimizes the cost of the overall systems that meet the given demand including the gas, district heating, and electricity systems. Annual gas and district heating demand are generated based on collected data from industries, commerce, and households and standard load profiles, while annual electricity demand is obtained from public statistics. Besides, hourly electricity demand data from industries, commerce, and households are collected. Results are compared with scenarios using standard load profiles for electricity. The results show that the use of Power-to-methane is significantly affected by the load profiles used as well as the existing technological mix.
Radon bursts
Authors: Woith Heiko
Published: March 2022

Radon timeseries typically contain a mixture of periodic and transient signals. Radon cycles can cover a broad frequency spectrum ranging from half-diurnal (S2, M2), daily (S1, O1), multiday, fortnightly, monthly, semi-annually, seasonal, to decadal variations. Physically, these variations are caused by a complex mix of meteorological parameters like air pressure, air temperature, wind, humidity, rain, snow, soil moisture, as well as pressure and temperature gradients in the ground or water level changes. In rare cases also Earth tides may modulate the radon signal. From time to time transient signals appear on top of these quasi-periodic signals – sometimes even in the form of radon bursts. These bursts are characterised by a sharp increase in radon concentration, often followed by a decay-like decrease. They last for hours, days, or months; they occur in soil, sediments, and rocks (granite, phyllite, lava), and appear in various geological environments (mofettes, mud volcanoes, volcanoes, rift systems). Spike-like bursts were also reported for other gases like methane or carbon dioxide. Deformation and related pore-pressure changes are discussed as physical origin of these transients. Spike-like anomalies are frequently claimed to be earthquake precursors. But they can also be caused by external events, like strong rainfall events, lake-level changes and even be artificially induced, e.g. by drilling activities. Thus my working hypothesis is that it is not possible to deduce the origin of a spike-like anomaly from its form and duration.
Groundwater quality determination using stable isotopes
Authors: Zupanc Vesna , Koroša Anja , Cerar Sonja , Urbanc Janko , Adu-Gyamfi Joseph , Halder Janine , Pintar Marina
Published: March 2022

Alluvial plains are an important agricultural area because of favourable soil properties, topography, and proximity to surface and groundwater resources. The predominant land use in the alluvial plains is agriculture, but there are also many urban and industrial areas. Groundwater bodies beneath the alluvial plains are threatened by nitrate pollution from agricultural activities and urban sources such as faulty sewage systems. For the Krško-Brežiško polje case study, an assessment of nitrate sources in groundwater was conducted using stable isotopes (δ15N) to produce maps of groundwater vulnerability. In addition, stable isotope composition of groundwater (δ18O and δ2H) was used to obtain information on the characteristics of the recharge area. Nuclear techniques (i.e., stable isotopes) are excellent for determining pathways and travel times of contaminants through the vadose zone in soil-groundwater systems, especially in areas with shallow aquifers. Results show contamination from manure application and the potential to reduce pressures on groundwater for specific sampling points.

This research was financed by the ARRS L4-8221 URAVIVO and IAEA TCP SLO5004 Improving Water Quality in Vulnerable and Shallow Aquifers under Two Intensive Fruit and Vegetable Production Zones.  
Distinguishing Direct Human-driven Changes in the Global Terrestrial Water Cycle
Authors: Kåresdotter Elisie , Kalantari Zahra , Destouni Georgia
Published: March 2022

Growing populations contribute to increased pressures on water resource availability. Understanding the impacts of various human pressures on terrestrial water flows is important to meet the challenges of sustainable water resource management. For useful assessment of and planning for societal water-availability impacts, it is also imperative to disentangle the direct influences of human activities in the landscape from external climate-driven influences on water flows and their variation and change. One approach to such disentanglement is to use a distributed global hydrological model that can realistically represent climate and direct anthropogenic modifications of the water system. This study uses this approach to quantify and separate the climate-driven change components of key hydrological variables (evapotranspiration, runoff, soil moisture, and storage change) from the human-driven change components that are modified by interventions such as dams, water reservoirs, and water withdrawals for irrigation, industry, and households. Using a global hydrological model in two different modes, one with and one without the inclusion of human activities, the result differences indicate the direct anthropogenic influences. Human activities are found to drive changes to all hydrological variables with different magnitudes and directions depending on geographic location. The largest differences between the pristine and the human-activity model runs are seen in regions with the highest population density. In such regions, which also tend to have relatively large numbers of dams used for irrigation, water storage is largely decreasing and feeding into increased runoff and evapotranspiration. Our findings provide new knowledge of how humans affect different hydrological fluxes and storages globally, including a more complete set of hydrological variables than in previous studies. This enables closure of hydrological balances and informs further research on historic and future hydrological trends, which is of special interest for areas lacking historic data and being particularly vulnerable to water availability changes.

Keywords: Hydrological variability and change; Global hydrological modeling; Anthropogenic change; Climate-driven change; Water fluxes and storages
A new framework for simultaneous inversions of deformation and gravity data applied to the 1982-1999 inflation at the Long Valley caldera
Authors: Nikkhoo Mehdi , Rivalta Eleonora
Published: March 2022

The location and volume change of pressurized magma chambers can be constrained by inverse modelling of the surface displacements they cause. Through a joint inversion of surface displacements and gravity changes the chamber mass change during the pressurization period can also be inferred. Such inversions often start with constraining the deformation source parameters using the deformation data alone (step 1). Using these parameters the gravity data are then corrected for the effect of mass redistribution in the host rocks and surface uplift/subsidence associated with the chamber expansion (step 2). Next, the corrected gravity changes together with the source location from the deformation inversion are used to infer the intrusion mass (step 3). Provided that the intrusion compressibility is known, the intrusion density can be estimated from the intrusion mass and source volume change from step 1 and step 3, respectively (step 4).

We show that the original gravity data (only corrected for ambient effects) are directly related to the deformation source parameters through the deformation-induced gravity changes and the free-air effect. Thus, both of these effects, which have been mostly considered as nuisance, in fact can be harvested to provide better constraints on the deformation source parameters and the mass changes. We propose a Bayesian framework for the joint inversion of deformation and gravity data by which all the deformation source parameters and chamber mass change are constrained simultaneously. This way, steps 1 to 3 of the previous approach are carried out at once. The advantages of the suggested approach are: (a) this way the gravity data help constrain deformation source parameters with smaller uncertainties, (b) it leads to a smaller uncertainty for the inferred mass change, (c) the optimal relative weights of various deformation and gravity datasets can be estimated as hyper-parameters within the Bayesian inference, thus, they are estimated directly and in an objective way, (c) the gravity and deformation stations need not be co-located, (d) errors associated with interpolation of vertical displacements at gravity benchmarks are avoided, (e) the uncertainty of vertical displacements is no longer propagated into the reduced gravity changes, and thus, mass changes are estimated more accurately.  

We apply this approach to the deformation and gravity data associated with the 1982-1999 inflation period at Long Valley caldera. The results agree with those from earlier efforts; however, show a clear improvement in the constrained source parameters and the intrusion mass. We discuss the implications and benefits of this approach depending on the relative quality of the deformation and gravity data.
Predicting evaporative loss at an Argentinian vineyard using a coupled water, vapor and heat flow model
Authors: Blöcher Johanna , Chmeis Arij , Kuraz Michal
Published: March 2022

Water resources in arid regions around the world are under a lot of strain due to extremely low precipitation rates and very high evaporation. In addition to water scarcity, irrigation methods can be inefficient. For example, over-irrigation beyond soil saturation can cause many problems, such as an increase in soil salinity and a decrease in productive soil capacity. This research aims to design a water content and soil temperature prediction system for an automated sensor monitoring system installed at the vineyard Ecohumus in San Juan province, Argentina. Short-term predictions of the water balance have the potential in delivering a useful tool to farmers for optimizing their irrigation water consumption.

For modeling soil water dynamics with evaporation and root water uptake losses, we use a coupled water, vapor, and heat flow model implemented in DRUtES software, Kuraz and Blöcher (2020). The model's top boundary condition solves the surface energy balance. For that we use weather forecast data and solar radiation as an input. The weather forecast is obtained from Norwegian meteorological institute (yr.no) using their API for developers which is provided as a free service. The solar radiation is computed based on equations suggested in the FAO Irrigation and Drainage guideline No. 56 and by Saito et al. (2006). Due to the lack of measurement data on the study site, soil hydraulic and thermal properties are estimated. We neglect the effect of soil organic matter in the water retention model and assume a homogeneous type of soil for the thermodynamic model. We establish communication with sensors installed in the soil for estimating initial conditions as well as with weather forecast service for estimating boundary conditions using our R script.

The result is output records that simulate pressure heads and water content distribution across the flow field over the simulated period. We present a system that describes the flow field allowing us to calculate evaporation rate changes with time, thereby optimizing the irrigation process according to soil and plant needs. This can be a helpful decision-making tool for farmers.
Climate Change on Extreme Winds Already Affects Wind Energy Availability in Europe
Authors: Rapella Lia , Faranda Davide , Gaetani Marco
Published: March 2022

Climate change is one of the most urgent challenges that humankind confronts nowadays. In order to mitigate its effects, the European Union aims to be climate-neutral, i.e. set the Greenhouse Gas (GHG) emissions to zero, by 2050. In this context, renewable energies (REs) play a key role: on the one hand their development and extensive usage can help to reduce the GHG emissions, on the other hand substantial local changes in atmospheric conditions could modify, for better or for worse, their efficiency. Extreme atmospheric events, in particular, can badly affect the efficiency of the RE infrastructures, preventing them from working or even damaging them. In this work, we focus on wind energy off shore, on the European panorama, with the purpose of estimate the behavior of extreme high winds, over the period 1950-2020, and their impact on wind energy availability. Indeed, the potential wind power production, according to the working regimes of a wind turbine, depends only on the wind speed and, over a certain wind speed threshold, called cut-off speed (25 m s-1), the turbine stops working. By using 6-hourly ERA5 reanalysis data-set and convection permitting simulations, covering the European domain and a period from 1950 to 2020 and from 2000 to 2009 respectively, we analysed the 100 m wind speed over the cut-off threshold and its relation with the geopotential height at 500 hPa, in order to investigate the large-scale weather regimes related to these extreme events. We focused especially on five regions, where high winds flow more frequently: United Kingdom, Denmark, Greece, and the areas off the south of France and north of Spain. By using the Mann-Kendall test, we analysed the trends in the occurrence of extreme events, and we detected significant increasing trends in large areas of the regions selected, particularly during the winter period (DJF). Finally, considering only the events over the 99th percentile, we found that they are often concurrently with storms, and, by means of the K-means clustering algorithm, we identified the different weather regimes at which they occur.
Machine learning-based attenuation of steeply dipping events of seismic reflection image beneath the Korean Peninsula
Authors: Song Youngseok , Byun Joongmoo , Kim Sooyoon , Choi Yonggyu , Bae Sungmyung
Published: March 2022

Seismic reflection images derived by ambient-noise seismic interferometry (SI) can show subsurface structures without active sources. To image and interpret the upper mantle structures and tectonic boundaries beneath the southern part of Korean Peninsula, we applied SI method to seismic ambient noise data recorded at 119 seismic stations on the Korean Peninsula in 2014 (from the seismic network of the Korean Meteorological Administration). The factor that makes interpretation difficult is the steeply dipping events in reflection images. Most of these events of apparent steeply dips show as true reflection events from steep geologic boundaries. Therefore, we need to attenuate these events to interpret true reflection events. These events overlap many times. Also, the value of the slope has several values close to half of the Rayleigh waves or P waves. To attenuate these events with these complex features, we used machine learning techniques. We attenuated our steeply dipping events by applying the Extraction of diffractions method. As the steeply dipping events are attenuated, horizontal events were strengthened, and noises were attenuated. We can more clearly identify the reflection events of the Moho discontinuity and the lithosphere/asthenosphere (LAB) boundary near the two-way reflection times of 7-11 s and 17-22 s respectively.
Assessing mechanisms and timing in magma-sediment interaction in the subseafloor: True 3-D microfabric observations provide insights into shallow sill emplacement processes
Authors: Kahl Wolf-Achim , Galerne Christophe , Bach Wolfgang
Published: March 2022

Magma emplacement in basin sediments at shallow levels initiates a plethora of processes, proceeding both simultaneously and sequential, and on variable length scales. On the grain scale, uptake and heating of sediment and pore fluids during magma emplacement, as well as the fractionation of a highly mobile fluid phase upon crystallization induce distinct rock microfabrics.  

 

IODP Expedition 385 drilled through the shallow sills emplaced in the active rift of the Guaymas Basin, Gulf of California. Here we present first results of a high-resolution X-ray µ-CT survey on drill core material recovered from Hole U1546, covering a shallow basaltic sill emplaced within 300 m below the seafloor. Comprising sample material from just a few meters from top and bottom contacts, from the center of the ca. 75 m thick sill, and a distinctly gabbroic region in the upper third of the sill, several characteristic features of the rock microfabric have been observed. In general, 3D quantitative digital image analysis of the porosity matches the trend determined by onboard moisture and density analyses. Detailed size and shape analysis reveal a bimodal distribution of the pores near the sill margins: Near the top contact, porosity is constituted by small interstitial pores and large spherical vesicles; Near the bottom contact, scarce pores comprise minute interstitial voids and dendritic cavities within granular concretions. While in the center layer of the sill pores are minuscule, porosity within the gabbroic region occurs as almost mm-sized interstitial cavities. The spherically-shaped large vesicles near the top contact feature a complex history: Ductile environment is required in the course of formation, and subsequent precipitation of zeolite or/and calcite can be observed. In places, iron sulfide is present near or at the vesicle walls. In addition, consideration of the grain phase allows further constraints. While plagioclase phenocrysts are abundant throughout the entire sill thickness, grain sizes of matrix pyroxenes and plagioclase near the center are larger than near the contact. In the gabbroic region the presence of hornblende is indicative of a water content of 2 to 3 wt.%. The induced lowering of the solidus temperatures in this region explains why very large crystal sizes are allowed to develop morphologies of pyroxene and plagioclase intergrowth resulting in a coarser gabbroic texture.
Assimilation frameworks for merging accelerometer derived thermospheric neutral mass density estimates with empirical and physical models
Authors: Forootan Ehsan , Kosary Mona , Farzaneh Saeed , Schumacher Maike
Published: March 2022

Atmospheric drag has a direct relationship with the thermospheric neutral density (TND) and represents a considerable impact on the precise orbit determination (POD) and prediction of low Earth orbit (LEO) satellites, for example those with the altitude of less than 1000 km, as well as space debris. The distribution of TND combined with the solar and geomagnetic activity has a direct impact on the electron distribution in the ionosphere. The latter is important for medium- and long-range high frequency communication, positioning, and over-the-horizon radar systems. New capabilities to understand, model and predict thermosphere variables are typically provided by models; however, the quality of them is limited due to their imperfect structure and uncertainty of their inputs. In this study, we present various data assimilation frameworks to take advantage of freely available accelerometer derived TNDs from GRACE, GRACE-FO and Swarm missions. This is realized by (1) formulating ensemble Kalman filter (EnKF)-based calibration and data assimilation (C/DA) procedures to update the model's states (and simultaneously calibrates its key parameters if needed); and (2) an empirical decomposition-based data assimilation is applied to merge satellite derived along-track estimates with global model derived TND simulations. The results of these two frameworks are then evaluated against independent measurements. The technical challenges and benefits are discussed in detail.
Variability of dissolved organic carbon (DOC) in the 6 largest Arctic rivers estimated using high resolution Sentinel-2 and Landsat-8 imageries over the 2013-2021 period.
Authors: Jégou Fabrice , Jallais Gaëtane , Salmon Elodie , Guenet Bertrand , Herrault Pierre-Alexis , Gogo Sébastien , Gandois Laure , Guimbaud Christophe , Laggoun-Defarge Fatima , Moulard Nathalie , Teisserenc Roman , Moquet Jean-Sébastien
Published: March 2022

Climate warming with permafrost thaw will modify lateral carbon export, from terrestrial to aquatic ecosystems with a potential huge impact on the Arctic rivers, draining organic-rich soils and in fine into the Arctic Ocean. The majority of annual DOC fluxes by Arctic rivers are transported during the snowmelt break-up period, which makes field measurements of DOC difficult. Passive spatial remote sensing is a very relevant tool to increase the spatial and temporal coverage of these observed values.

In the framework of the French CNES DOC-Rivers project we proposed to apply the approach consisting in analyzing satellite imageries to evaluate DOC concentrations in the 6 great Arctic Rivers: Lena, Ob’, Yenisey, Yukon, MacKenzie, Kolyma. The algorithm, first, establishes a multi-linear relationship between ground-based chromatic dissolved organic matter (CDOM) observations and specific satellite color bands to construct a complete satellite CDOM database. Another linear regression is used afterward with in-situ data from the Arctic Great Rivers Observatory (ArcticGRO) initiative to correlate CDOM and DOC observations. Using this second linear regression, we can predict the DOC content from the previous construct satellite CDOM database. River discharge measurements from the ArcticGRO database also enable to estimate the evolution of DOC export to the Arctic Ocean from satellite data.

We applied this approach to high-resolution satellite data issued from Sentinel 2 (A 2015-2022, B 2017-2022) and Landsat 8 (2013-2022) to create a multi-instrumental synergy. This new database provides an unprecedented source of information for understanding DOC dynamics of in Arctic rivers and assessing its transfer from large catchments to the Arctic Ocean. This database provides information on the variability of DOC during the whole ice-free season and serve to locate areas with higher concentrations and fluxes during the 2013-2021 period. We plan to complement our database on future period with data from new satellite missions (Landsat 9, Sentinel 2C), on the present time with data from on-going missions (Sentinel 3, MODIS) and on past period with data from low resolution observations as Landsat 5 and Landsat 7. This extension of the database over a longer period of time will furnish insight in response to climate warming.
Water use of drought-tolerant coniferous trees (Pinus brutia and Cupressus sempervirens) in a semi-arid environment
Authors: Djuma Hakan , Bruggeman Adriana , Eliades Marinos , Zoumides Christos , Siakou Melpomeni , Fasakhondi Mohsen
Published: March 2022

Observing ecohydrological processes of indigenous, drought-tolerant trees in arid and semi-arid regions is of profound importance for assessing the suitability of plant species for future climate conditions. The objective of this study is to quantify transpiration and soil moisture of pine (Pinus brutia) and cypress (Cupressus sempervirens) trees. The study site is located in Athalassa Forest Park, in Cyprus. The site has a surface area of 10 ha with an average slope of 4%. Average annual rainfall is 315 mm with a mean daily minimum temperature of 5° C during January and a mean daily maximum temperature of 37° C during August. The site was converted in 2011 from rainfed agriculture to a mixed forest by planting seedlings of different tree and shrub species.

Six P. brutia and six C. sempervirens trees were randomly selected for sap flow monitoring with sensors (heat ratio method) attached to the tree trunks. Forty-five soil moisture sensors were installed under the canopy, the edge of canopy and areas with no tree canopy at depths of 10 cm, 30 cm and 50 cm. Data from November 2020 to December 2021 indicated that mean total transpiration per tree was higher for C. sempervirens (≅2.2 m3) than for P. brutia (≅1.3 m3). Total rainfall during these 14 months was 339 mm. Higher transpiration of cypress trees was also reflected in the soil moisture, as canopy area soil moisture contents were generally lower for cypress than for pine for the depths of 10 and 50 cm. After rain maximum soil moisture values were similar for cypress and pine at the depth of 30 cm but the reduction of soil moisture over time was quicker for cypress. 

This research has received support from the Water JPI (Joint Call 2018) FLUXMED Project, funded through the Cyprus Research and Innovation Foundation.
Homo heterogenus: Variability in Pleistocene Homo environments.
Authors: Foister Tegan , Tallavaara Miikka , Fortelius Mikael , Wilson Oscar E.
Published: March 2022

The Early Pleistocene dispersal of Homo out of Africa  is a highly studied and debated topic.  One of the controversies centres on the question of what type of environments hominin species expanded out of Africa into. We conducted a literature review of 163 papers published since 2000 studying the environmental settings of the first Out of Africa expansion. We found that the literature is polarised between two types of hypotheses. On one hand there are papers which describe Homo in the Early Pleistocene as inflexible (compared to Homo sapiens) and incapable of persisting in non-savannah environments, e.g. the ‘savannahstan’ hypothesis. On the other hand there are papers which describe Homo as flexible and able to persist in various environment types, e.g. the variability selection hypothesis. By investigating these hypotheses we are able to move closer to answering the question - as Homo dispersed out of Africa, did they diversify to exploit new environments, or remain within the ranges of their African niche? We analysed the reconstructions of early Homo environments included in these papers. We found that the qualitative language used to describe hominin environments is problematic and impedes the formation of clear conclusions about the environments occupied by early Homo species. However, by forcibly quantifying the descriptions used in 69 (of the original 163) papers we found that the research does not strongly support the savannahstan hypothesis. Instead the environments inhabited by Homo are consistently reconstructed as a mix of environment types (grassland, forest, savannah etc.), with a slight skew towards open habitats. Based on these results, we tentatively suggest that Homo exhibited a preference for heterogeneous “edge” environments during the Pleistocene and as they dispersed out of Africa. However,  in order to further investigate the potential preference of Homo for heterogeneous environments and to build confidence in reconstructions of early human environments in general, quantified reconstructions of the vegetation composition and distribution at early Homo sites are needed. 
Review of application of geostatistical techniques to groundwater salinization problems
Authors: Panagiotou Constantinos F. , Kyriakidis Phaedon , Tziritis Evangelos
Published: March 2022

Groundwater salinization is a complex and dynamic process often related to multiple causes, such as seawater intrusion, soil salinization associated with water irrigation, and geogenic factors such as evaporate dissolution. Consequently, a reliable assessment of salinization risks depends heavily on the ability of statistical methods to accurately capture the spatial variability and interrelation among salinization indicators. Geostatistical methods are often used to identify and map salinization-affected regions, investigate how salinization indicators influence groundwater mechanisms, and eventually design optimal groundwater management policies.

In the context of the MEDSAL Project (www.medsal.net), this study reviews the recent key applications of geostatistical methods to address problems relevant to groundwater salinization. The basic principles of geostatistics are briefly described, and several studies are discussed that employ geostatistical and multivariate tools for identifying salinization sources, clarifying the relationship among salinization indicators and groundwater processes, and facilitating uncertainty propagation in physically-based models of the groundwater systems affected by salinization.

The literature review identifies most used methods and offers several recommendations in terms of future directions and challenges on the role of geostatistics for improved mapping of the spatial and/or spatiotemporal distribution of geochemical data related to salinization. These recommendations include the integration of geostatistics and machine learning methods for improved understanding and modeling of groundwater salinization processes, as well as the application of modern geostatistical simulation algorithms, accounting for diverse information sources, for exploring parameter uncertainty in spatially distributed hydrogeochemical models.
An Assessment of the Role of Ionospheric Conductances in Magnetosphere-Ionosphere-Thermosphere Coupling at Giant Planets, Based on Space Data and Modelling Tools
Authors: Clement Noe , Al Saati Sariah , Blanc Michel , Wang Yuxian , Louis Corentin , Tao Chihiro , Gérard Jean-Claude
Published: March 2022

The dynamics of giant planets magnetosphere is controlled by a complex interplay between these planets fast rotation, their solar-wind interaction, and possible moon plasma and momentum sources. At the ionospheric level, two key parameters controlling the degree of coupling of magnetospheric motions to planetary rotation are the Pedersen and Hall ionospheric conductances, which regulate the intensity of currents coupling magnetosphere and ionosphere and the rate of transfer of angular momentum and power between them. In this talk we will present a parametric study of the dependence of Pedersen and Hall conductances on the structure and composition of these planets upper atmospheres and on the characteristics of auroral and polar particle precipitation, using generic thermospheric and ionospheric models and ground-truth validation by Juno, Cassini and Voyager data. We will discuss the implications on the degree of importance that the thermosphere-ionosphere has in the enforcement of corotation of the magnetospheric plasma.
Soil aggregation impacts bacterial community assembly and suppression of Ralstonia disease in tomato
Authors: Dong Menghui
Published: March 2022

Soil aggregation is a key element of soil structure, providing a range of micro-niches for soil-borne microorganisms and creating fine-scale heterogeneity in physical and chemical properties. Soil microorganisms drive a range of critical terrestrial ecosystem functions. The importance of understanding the impact of soil aggregates on microbiome assembly and function is increasingly becoming appreciated. In this study, we used a long-term tomato monoculture field as a model system to investigate the impact of soil aggregates on bacterial community assembly and inhibition of the pathogen Ralstonia solanacearum. Samples were collected after harvest from experimental fields with either no fertilizer (CK), chemical fertilizer (CF), organic fertilizer (BF) or a bio-organic fertilizer (BF) and separated into categories of soil aggregates (e.g. <0.25 mm, 0.25-1 mm, 1-2 mm, >2 mm) by a wet-sieving method. Bacterial community composition was found to differ significantly across aggregate fractions, and bacterial communities from larger aggregate fractions exhibited a higher degree of phylogenetic clustering. Furthermore, we found that soil aggregate size classes differed in the relative importance of deterministic versus stochastic processes Fields with different fertilization differ in soil aggregates distribution and disease suppression. Fields with organic inputs (OF, BF) had a higher abundance of large macro-aggregates and fewer micro-aggregates than inorganic input treatments (CK, CF). Meanwhile, disease incidences were lowest in BF, then increasing in OF, CF and CK, orderly. Interestingly, only relative density of R. solanacearum in micro-aggregates was positively correlated with disease. Furthermore, in experiments involving inoculation of R. solanacearum into aggregate size fractions recovered from field samples, only micro-aggregates (<0.25 mm) from the low disease incidence soil (BF) showed significantly higher resistance against pathogen invasion as compared to the high disease incidence soil (CF). In summary, under agricultural practice, soil aggregates can mediate the ecological assembly processes of bacterial communities, thereby influences the suppression of bacterial wilt disease. Soil structure and aggregation should therefore be considered in strategies to improve soil-borne resistance to plant pathogens.
Attribution of seasonally relevant winter and spring climate indices in Hungary
Authors: Szabó Péter , Bartholy Judit , Barna Zsófia , Bokros Kinga , Bordi Sára , Mráz Anna , Pieczka Ildikó , Pongrácz Rita
Published: March 2022

Although anthropogenic global warming is well-known within the scientific community, the public is still not certain how to associate specific local weather and climate events to this issue. Therefore, it is essential to raise public awareness by providing sound and readily understood scientific information, and to explain how humans contribute to specific (extreme) events. Although a few case studies for past high-impact weather events were assessed in Hungary, a systematic analysis of long-term past and future trends of these indices is missing, and their linkage to anthropogenic activity has not been addressed at all. Our attribution project (started in September 2021) aims to fill this gap in Hungary: the results of the analysis of seasonally relevant indices are published in each season at the time of an (extreme) event occurrence. The dissemination is done via an already established Hungarian platform (https://masfelfok.hu/) reaching the public with readily understood climate change information through their broad media coverage and a large social media network.

The assessments are prepared within the project using several data sources: (1) an ensemble of CMIP6 global climate model simulations of both natural-only forcings and historical runs, (2) an ensemble of regional climate model simulations from Euro-CORDEX, including both RCP4.5 and RCP8.5 scenarios, (3) a fine-resolution, homogenized observation-based gridded data for Hungary, (4) the ERA5 reanalysis. We address seasonally relevant extreme and compound events, and the attribution of pre-selected indices to anthropogenic activity through their intensity, duration, and frequency changes. For instance, frost days, annual temperature minima and return values, snowfall and heavy snowfall days are evaluated for winter, while the start of vegetation period, late frost, dry and heavy precipitation days for spring, as they are of most public interest. Furthermore, we determine how many seasonal record low/record high breakings happen and how large area within the domain is affected.

Preliminary winter results suggest that the decrease of frost days in Hungary is clearly due to anthropogenic activity, while it is not the case for the annual minimum temperatures but will be in the future. No significant decrease has been detected for the snowfall and heavy snowfall days, and the effects of anthropogenic activity on these indices will only occur following the pessimistic future scenario.
Influence of Boulders on Channel Width and Slope in Bedrock Rivers
Authors: Nativ Ron , Turowski Jens , Goren Liran , Laronne Jonathan , H. Shyu J. Bruce
Published: March 2022

Large boulders with a diameter of up to several tens of meters are globally observed in mountainous bedrock channel environments. Recent theories suggest that high concentrations of boulders are associated with changes in channel morphology. However, data are scarce and ambiguous, and process-related studies are limited. Here we present data from the Liwu River, Taiwan, showing that channel width and slope increase with boulder concentration. We apply two mass balance principles of bedrock erosion and sediment transport and develop a theory to explain the steepening and widening trends. Five mechanisms are considered and compared to the field data. The cover effect by immobile boulders is found to have no influence on channel width. Channel width can partially be explained by boulder control on the tools effect and on the partitioning of the flow shear stress. However, none of the mechanisms we explored can adequately explain the scattered width data, potentially indicating a long-timescale adjustment of channel width to boulder input. Steepening can be best described by assuming a reduction of sediment transport efficiency with boulder concentration. We find that boulders represent a significant perturbation to the fluvial landscape. Channels tend to adjust to this perturbation leading to a new morphology that differs from boulder-free channels. The general approach presented here can be further expanded to explore the role of other boulder-related processes.   