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Fatima Laggoun-défarge - One of the best experts on this subject based on the ideXlab platform.
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Geochemical insights into spatial and temporal evolution of sediment at catchment scale (Egoutier stream, France)
Applied Geochemistry, 2020Co-Authors: Lauriane Ledieu, Anaëlle Simonneau, O. Cerdan, P. Négrel, V. Laperche, Cécile Grosbois, Fatima Laggoun-défargeAbstract:The transfer and storage of chemical elements in particulate matter are controlled by physical, chemical and biological processes. Their dynamics are well understood, especially in environments that show strong tectonic and/or geomorphic pressures, and are frequently reconstructed over centuries or decades to evaluate climate change effects for example. However, observations carried out at high spatial and temporal resolutions are less common, particularly in lowland areas. The present study aimed to better understand the links between earth surface processes, such as soil weathering and erosion, by combining pedology, geochemistry and hydrology at a small catchment scale. It focuses on the transfer of selected chemical elements (Ca, K, Ti, Fe, Mn, Rb and Sr) associated with particulate erosion and transport. The first (Topsoil) and last (subsoil) soil horizons from different soil profiles and stream bed-load sediments of the Egoutier catchment (8 km2, Loiret, France) were studied. The objective was to investigate the relationship between the weathering and erosion processes. The soils are developed on ancient alluvium as evidenced by their physical and chemical properties, which clearly displayed a weathering profile from bedrock to Topsoil layers. Ca, Fe and Rb showed migration dynamics from the Topsoils to the subsoils, whereas Mn appeared immobilized within Topsoils. Enrichments of all investigated elements increased in bed-load sediments. Topsoil erosion is the main source of sediment. However, Fe and Rb enrichments also highlight the remobilization of subsoils during periods of enhanced precipitation. Furthermore, Fe and Rb enrichments show a selective erosion of clay minerals. K and Sr contents evidence mineral break-up processes favoring mechanical erosion of all mineral phases. Moreover, their enrichments can be interpreted as the result of higher erosion rates and deposition during high rainfall events. The same conclusion can be drawn for Mn and Ca although their spatial variabilities depend on contributions from runoff in urban areas, as rainwaters from anthropized areas supply Ca mineral phases and diluted Mn depleted bearing phases from Topsoil layers.
E. Gonzalez Sosa - One of the best experts on this subject based on the ideXlab platform.
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Impact of land use on the hydraulic properties of the Topsoil in a small French catchment
Hydrological Processes, 2010Co-Authors: E. Gonzalez Sosa, I. Braud, J. Dehotin, L. Lassabatère, R. Angulo Jaramillo, M. Lagouy, F. Branger, C. Jacqueminet, S. Kermadi, K. MichelAbstract:The hydraulic properties of the Topsoil control the partition of rainfall into infiltration and runoff at the soil surface. They must be characterized for distributed hydrological modelling. This study presents the results of a field campaign documenting Topsoil hydraulic properties in a small French suburban catchment (7 km2) located near Lyon, France. Two types of infiltration tests were performed: single ring infiltration tests under positive head and tension-disk infiltration using a mini-disk. Both categories were processed using the BEST--Beerkan Estimation of Soil Transfer parameters--method to derive parameters describing the retention and hydraulic conductivity curves. Dry bulk density and particle size data were also sampled. Almost all the Topsoils were found to belong to the sandy loam soil class. No significant differences in hydraulic properties were found in terms of pedologic units, but the results showed a high impact of land use on these properties. The lowest dry bulk density values were obtained in forested soils with the highest organic matter content. Permanent pasture soils showed intermediate values, whereas the highest values were encountered in cultivated lands. For saturated hydraulic conductivity, the highest values were found in broad-leaved forests and small woods. The complementary use of tension-disk and positive head infiltration tests highlighted a sharp increase of hydraulic conductivity between near saturation and saturated conditions, attributed to macroporosity effect. The ratio of median saturated hydraulic conductivity to median hydraulic conductivity at a pressure of − 20 mm of water was about 50. The study suggests that soil texture, such as used in most pedo-transfer functions, might not be sufficient to properly map the variability of soil hydraulic properties. Land use information should be considered in the parameterizations of Topsoil within hydrological models to better represent in situ conditions, as illustrated in the paper. Copyright © 2010 John Wiley & Sons, Ltd.
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Impact of land use on the hydraulic properties of the Topsoil in a small French catchment
Hydrological Processes, 2010Co-Authors: E. Gonzalez Sosa, I. Braud, J. Dehotin, L. Lassabatère, R. Angulo Jaramillo, M. Lagouy, F. Branger, C. Jacqueminet, S. Kermadi, K. MichellAbstract:The hydraulic properties of the Topsoil control the partition of rainfall into infiltration and runoff at the soil surface. They must be characterized for distributed hydrological modelling. This study presents the results of a field campaign documenting Topsoil hydraulic properties in a small French suburban catchment (7 km2) located near Lyon, France. Two types of infiltration tests were performed: single ring infiltration tests under positive head and tension disk infiltration using a mini-disk. Both categories were processed using the BEST Beerkan Estimation of Soil Transfer parameters- method to derive parameters describing the retention and hydraulic conductivity curves. Dry bulk density and particle size data were also sampled. Almost all the Topsoils were found to belong to the sandy loam soil class. No significant differences in hydraulic properties were found in terms of pedologic units, but the results showed a high impact of land use on these properties. The lowest dry bulk density values were obtained in forested soils with the highest organic matter content. Permanent pasture soils showed intermediate values, whereas the highest values were encountered in cultivated lands. For saturated hydraulic conductivity, the highest values were found in broad leaved forests and small woods. The complementary use of tension disk and positive head infiltration tests highlighted a sharp increase of hydraulic conductivity between near saturation and saturated conditions, attributed to macroporosity effect. The ratio of median saturated hydraulic conductivity to median hydraulic conductivity at a pressure of -20 mm of water, was about 50. The study suggests that soil texture, such as used in most pedo-transfer functions, might not be sufficient to properly map the variability of soil hydraulic properties. Land use information should be considered in the parameterizations of Topsoil within hydrological models to better represent in situ conditions, as illustrated in the paper.
Antje Gittel - One of the best experts on this subject based on the ideXlab platform.
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Soil organic matter quality exerts a stronger control than stoichiometry on microbial substrate use efficiency along a latitudinal transect
eScholarship University of California, 2018Co-Authors: Takriti Mounir, Birgit Wild, Ricardo Eloy J Alves, Norman Gentsch, Antje Gittel, Anna Knoltsch, Jörg Schnecker, Maria Mooshammer, Nikolay Lashchinskiy, Robert MikuttaAbstract:A substantial portion of soil organic matter (SOM) is of microbial origin. The efficiency with which soil microorganisms can convert their substrate carbon (C) into biomass, compared to how much is lost as respiration, thus co-determines the carbon storage potential of soils. Despite increasing insight into soil microbial C cycling, empirical measurements of microbial C processing across biomes and across soil horizons remain sparse. The theory of ecological stoichiometry predicts that microbial carbon use efficiency (CUE), i.e. growth over uptake of organic C, strongly depends on the relative availability of C and nutrients, particularly N, as microorganisms will either respire excess C or conserve C while mineralising excess nutrients. Microbial CUE is thus expected to increase from high to low latitudes and from Topsoil to subsoil as the soil C:N and the stoichiometric imbalance between SOM and the microbial biomass decrease. To test these hypotheses, we collected soil samples from the organic Topsoil, mineral Topsoil, and mineral subsoil of seven sites along a 1500-km latitudinal transect in Western Siberia. As a proxy for CUE, we measured the microbial substrate use efficiency (SUE) of added substrates by incubating soil samples with a mixture of 13C labelled sugars, amino sugars, amino acids, and organic acids and tracing 13C into microbial biomass and released CO2. In addition to soil and microbial C:N stoichiometry, we also determined the potential extracellular enzyme activities of cellobiohydrolase (CBH) and phenol oxidase (POX) and used the CBH:POX ratio as an indicator of SOM substrate quality. We found an overall decrease of SUE with latitude, corresponding to a decrease in mean annual temperature, in mineral soil horizons. SUE decreased with decreasing stoichiometric imbalance in the organic and mineral Topsoil, while a relationship of SUE with soil C:N was only found in the mineral Topsoil. However, contrary to our hypothesis, SUE did not increase with soil depth and mineral subsoils displayed lower average SUE than mineral Topsoils. Both within individual horizons and across all horizons SUE was strongly correlated with CBH:POX ratio as well as with climate variables. Since enzyme activities likely reflect the chemical properties of SOM, our results indicate that SOM quality exerts a stronger control on SUE than SOM stoichiometry, particularly in subsoils were SOM has been turned over repeatedly and there is little variation in SOM elemental ratios
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microbial community composition shapes enzyme patterns in Topsoil and subsoil horizons along a latitudinal transect in western siberia
Soil Biology & Biochemistry, 2015Co-Authors: Jörg Schnecker, Birgit Wild, Mounir Takriti, Ricardo Eloy J Alves, Norman Gentsch, Antje Gittel, Karoline Klaus, Angelika Hofer, Anna KnoltschAbstract:Soil horizons below 30 cm depth contain about 60% of the organic carbon stored in soils. Although insight into the physical and chemical stabilization of soil organic matter (SOM) and into microbial community composition in these horizons is being gained, information on microbial functions of subsoil microbial communities and on associated microbially-mediated processes remains sparse. To identify possible controls on enzyme patterns, we correlated enzyme patterns with biotic and abiotic soil parameters, as well as with microbial community composition, estimated using phospholipid fatty acid profiles. Enzyme patterns (i.e. distance-matrixes calculated from these enzyme activities) were calculated from the activities of six extracellular enzymes (cellobiohydrolase, leucine-amino-peptidase, N-acetylglucosaminidase, chitotriosidase, phosphatase and phenoloxidase), which had been measured in soil samples from organic Topsoil horizons, mineral Topsoil horizons, and mineral subsoil horizons from seven ecosystems along a 1500 km latitudinal transect in Western Siberia. We found that hydrolytic enzyme activities decreased rapidly with depth, whereas oxidative enzyme activities in mineral horizons were as high as, or higher than in organic Topsoil horizons. Enzyme patterns varied more strongly between ecosystems in mineral subsoil horizons than in organic Topsoils. The enzyme patterns in Topsoil horizons were correlated with SOM content (i.e., C and N content) and microbial community composition. In contrast, the enzyme patterns in mineral subsoil horizons were related to water content, soil pH and microbial community composition. The lack of correlation between enzyme patterns and SOM quantity in the mineral subsoils suggests that SOM chemistry, spatial separation or physical stabilization of SOM rather than SOM content might determine substrate availability for enzymatic breakdown. The correlation of microbial community composition and enzyme patterns in all horizons, suggests that microbial community composition shapes enzyme patterns and might act as a modifier for the usual dependency of decomposition rates on SOM content or C/N ratios.
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Distinct microbial communities associated with buried soils in the Siberian tundra.
The ISME journal, 2013Co-Authors: Antje Gittel, Birgit Wild, Jörg Schnecker, Jiří Bárta, Iva Kohoutová, Robert Mikutta, Sarah M. Owens, Jack A. Gilbert, Bjarte Hannisdal, Joeran MaerzAbstract:Cryoturbation, the burial of Topsoil material into deeper soil horizons by repeated freeze–thaw events, is an important storage mechanism for soil organic matter (SOM) in permafrost-affected soils. Besides abiotic conditions, microbial community structure and the accessibility of SOM to the decomposer community are hypothesized to control SOM decomposition and thus have a crucial role in SOM accumulation in buried soils. We surveyed the microbial community structure in cryoturbated soils from nine soil profiles in the northeastern Siberian tundra using high-throughput sequencing and quantification of bacterial, archaeal and fungal marker genes. We found that bacterial abundances in buried Topsoils were as high as in unburied Topsoils. In contrast, fungal abundances decreased with depth and were significantly lower in buried than in unburied Topsoils resulting in remarkably low fungal to bacterial ratios in buried Topsoils. Fungal community profiling revealed an associated decrease in presumably ectomycorrhizal (ECM) fungi. The abiotic conditions (low to subzero temperatures, anoxia) and the reduced abundance of fungi likely provide a niche for bacterial, facultative anaerobic decomposers of SOM such as members of the Actinobacteria, which were found in significantly higher relative abundances in buried than in unburied Topsoils. Our study expands the knowledge on the microbial community structure in soils of Northern latitude permafrost regions, and attributes the delayed decomposition of SOM in buried soils to specific microbial taxa, and particularly to a decrease in abundance and activity of ECM fungi, and to the extent to which bacterial decomposers are able to act as their functional substitutes.
Michal Sněhota - One of the best experts on this subject based on the ideXlab platform.
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Estimates of Tillage and Rainfall Effects on Unsaturated Hydraulic Conductivity in a Small Central European Agricultural Catchment
Water, 2019Co-Authors: David Zumr, Vladimír Klípa, Jakub Jeřábek, Michal Dohnal, Michal SněhotaAbstract:In arable land, Topsoil is exposed to structural changes during each growing season due to agricultural management, climate, the kinetic energy of rainfall, crop and root growth. The shape, size, and spatial distributions of soil aggregates are considerably altered during the season and thus affect water infiltration and the soil moisture regime. Agricultural Topsoils are prone to soil compaction and surface sealing which result in soil structure degradation and disconnection of preferential pathways. To study Topsoil infiltration properties over time, near-saturated hydraulic conductivity of Topsoil was repeatedly assessed in a catchment in central Bohemia (Czech Republic) during three consecutive growing seasons, using a recently developed automated tension minidisk infiltrometer (MultiDisk). Seasonal variability of soil bulk density and saturated water content was observed as Topsoil consolidated between seedbed preparations. Topsoil unsaturated hydraulic conductivity was lower in spring and increased in the summer months during two seasons, and the opposite trend was observed during one season. Temporal unsaturated hydraulic conductivity variability was higher than spatial variability. Cumulative kinetic energy of rainfall, causing a seasonal decrease in soil macroporosity and unsaturated hydraulic conductivity, was not a statistically significant predictor.
K. Michell - One of the best experts on this subject based on the ideXlab platform.
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Impact of land use on the hydraulic properties of the Topsoil in a small French catchment
Hydrological Processes, 2010Co-Authors: E. Gonzalez Sosa, I. Braud, J. Dehotin, L. Lassabatère, R. Angulo Jaramillo, M. Lagouy, F. Branger, C. Jacqueminet, S. Kermadi, K. MichellAbstract:The hydraulic properties of the Topsoil control the partition of rainfall into infiltration and runoff at the soil surface. They must be characterized for distributed hydrological modelling. This study presents the results of a field campaign documenting Topsoil hydraulic properties in a small French suburban catchment (7 km2) located near Lyon, France. Two types of infiltration tests were performed: single ring infiltration tests under positive head and tension disk infiltration using a mini-disk. Both categories were processed using the BEST Beerkan Estimation of Soil Transfer parameters- method to derive parameters describing the retention and hydraulic conductivity curves. Dry bulk density and particle size data were also sampled. Almost all the Topsoils were found to belong to the sandy loam soil class. No significant differences in hydraulic properties were found in terms of pedologic units, but the results showed a high impact of land use on these properties. The lowest dry bulk density values were obtained in forested soils with the highest organic matter content. Permanent pasture soils showed intermediate values, whereas the highest values were encountered in cultivated lands. For saturated hydraulic conductivity, the highest values were found in broad leaved forests and small woods. The complementary use of tension disk and positive head infiltration tests highlighted a sharp increase of hydraulic conductivity between near saturation and saturated conditions, attributed to macroporosity effect. The ratio of median saturated hydraulic conductivity to median hydraulic conductivity at a pressure of -20 mm of water, was about 50. The study suggests that soil texture, such as used in most pedo-transfer functions, might not be sufficient to properly map the variability of soil hydraulic properties. Land use information should be considered in the parameterizations of Topsoil within hydrological models to better represent in situ conditions, as illustrated in the paper.