Search results for "soil"
showing 10 items of 3493 documents
Prediction models based on soil properties for evaluating the uptake of eight heavy metals by tomato plant (Lycopersicon esculentum Mill.) grown in a…
2021
The aim of this study is to design de novo prediction models in order to gauge the likely uptake of eight heavy metals (Al, Cr, Cu, Fe, Mn, Ni, Pb and Zn) by Lycopersicon esculentum, the tomato plant. Uptake was assessed within the plant’s root, stem, leaf and fruit tissues, respectively. The plant was cultivated in soil amended by different application rates of sewage sludge, i.e. 0, 10, 20, 30 and 40 g/kg. The roots exhibited markedly elevated heavy metal concentrations compared to the above-ground plant components, with the exception of the quantity of Ni in the leaves. Apart from Al, Fe and Mn, a bioconcentration factor >1 was identified for all heavy metals. Excluding Ni in the leaves,…
The effect of spent bleaching earth ageing process on its physicochemical and microbial composition and its potential use as a source of fatty acids …
2014
This study was aimed at investigating the physicochemical and microbiological changes that took place during the ageing process of spent bleaching earth in the presence of autochthonous microorganisms. Research material included fresh spent bleaching earth (SBE0) and the same material after 3 years of storage at the constant temperature of 20 °C, without aeration and moistening (SBE3). Changes in the chemical composition of analysed waste material were observed during its ageing process point to a spontaneous bioconversion of fat substance towards formation and/or release of free saturated fatty acids C16:0 and C18:0 (14.3 g 100 g(-1) D.M.), triterpenes (8.48 g 100 g(-1) D.M.), cholesterol …
Mapping and determinism of soil microbial community distribution across an agricultural landscape.
2015
Article en open access; International audience; Despite the relevance of landscape, regarding the spatial patterning of microbial communities and the relative influence of environmental parameters versus human activities, few investigations have been conducted at this scale. Here, we used a systematic grid to characterize the distribution of soil microbial communities at 278 sites across a monitored agricultural landscape of 13km(2). Molecular microbial biomass was estimated by soil DNA recovery and bacterial diversity by 16S rRNA gene pyrosequencing. Geostatistics provided the first maps of microbial community at this scale and revealed a heterogeneous but spatially structured distribution…
Impact des digestats de méthanisation sur la qualité biologique des sols agricoles : nécessité de générer de nouvelles données pour objectiver
2021
National audience; La méthanisation est une technologie basée sur la dégradation par des micro-organismes de la matière organique, en conditions contrôlées et en l'absence dioxygène. Cette dégradation aboutit à la production d'un biogaz utilisé comme énergie renouvelable et d'un co-produit riche en matière organique appelé digestat. Ce digestat est au cœur de nombreuses interrogations, concernant les impacts engendrés par son épandage sur les sols. Avec l'essor de la méthanisation, la recherche s'intéresse à ses effets, afin de conserver des sols de qualité.
Quantifying biogeochemical heterogeneity in soil systems
2018
© 2018 Elsevier B.V. Soils are increasingly perceived as complex systems with properties and biogeochemical functions that vary on millimeter scales. Quantitative information about the resulting biogeochemical heterogeneity is needed to improve process knowledge and to render biogeochemical models more mechanistic. Here we demonstrate how standardized arrays of Pt-electrodes can be used to quantify biogeochemical or ‘functional’ soil heterogeneity, defined as the extent to which the soil is subdivided into microenvironments. Our case study confirmed the validity of this approach for a soil sequence consisting of a well-drained, a moderately well drained and a poorly drained Mollisol. We fou…
Consequence of litter removal on pedogenesis: A case study in Bachs and Irchel (Switzerland)
2016
In forests, soils contain at least twice as much carbon than plants that mostly grow in the upper layers. Litter at the interface between soils and the atmosphere regulates a variety of biogeochemical cycles, which are important for both plants and soils and have possible implications for other environmental components. We have compared leachates collected during an incubation experiment on: a) beech and oak leaves; b) organic subhorizons OLn, OLv, OF, and mineral A horizon; c) treated with litter removal (and untreated) plots, to assess the changes in the chemical composition of the litter layers and leachates during weathering and their influence on the underlying horizons. . Two differen…
HONO Emissions from Soil Bacteria as a Major Source of Atmospheric Reactive Nitrogen
2013
From Soil to Sky Trace gases emitted either through the activity of microbial communities or from abiotic reactions in the soil influence atmospheric chemistry. In laboratory column experiments using several soil types, Oswald et al. (p. 1233 ) showed that soils from arid regions and farmlands can produce substantial quantities of nitric oxide (NO) and nitrous acid (HONO). Ammonia-oxidizing bacteria are the primary source of HONO at comparable levels to NO, thus serving as an important source of reactive nitrogen to the atmosphere.
Storage and release of fossil organic carbon related to weathering of sedimentary rocks
2007
International audience; The biogeochemical carbon cycle, which plays an undeniable role in global climate change, is defined both by the size of carbon reservoirs (such as the atmosphere, biomass, soil and bedrock) and the exchange between them of various mineral and organic carbon forms. Among these carbon forms, fossil organic carbon (FOC) (i.e., the ancient organic matter stored in sedimentary rocks) is widely observed in modern environments but is not included in the supergene carbon budget. Using a digitized map of the world and an existing model of CO2 consumption associated with rock weathering, we establish the global distribution of FOC stored in the first meter of sedimentary rock…
Impact of hydrologically driven hillslope erosion and landslide occurrence on soil organic carbon dynamics in tropical watersheds
2016
The dynamics of soil organic carbon (SOC) in tropical forests play an important role in the global carbon (C) cycle. Past attempts to quantify the net C exchange with the atmosphere in regional and global budgets do not systematically account for dynamic feedbacks among linked hydrological, geomorphological, and biogeochemical processes, which control the fate of SOC. Here we quantify effects of geomorphic perturbations on SOC oxidation and accumulation in two adjacent wet tropical forest watersheds underlain by contrasting lithology (volcaniclastic rock and quartz diorite) in the Luquillo Critical Zone Observatory. This study uses the spatially-explicit and physically-based model of SOC dy…
Spatial distribution of N-cycling microbial communities showed complex patterns in constructed wetland sediments.
2013
International audience; Constructed wetlands are used for biological treatment of wastewater from agricultural lands carrying pollutants such as nitrates. Nitrogen removal in wetlands occurs from direct assimilation by plants and through microbial nitrification and denitrification. We investigated the spatial distribution of N-cycling microbial communities and genes involved in nitrification and denitrification in constructed wetland sediments receiving irrigation water. We used quantitative real-time PCR (qPCR) to characterize microbial communities. Geostatistical variance analysis was used to relate them with vegetation cover and biogeochemical sediment properties. The spatial distributio…