Search results for "ORGANIC MATTER"
showing 10 items of 577 documents
Anaerobic oxidation of methane in sediments of a nitrate-rich, oligo-mesotrophic boreal lake
2021
AbstractThe identity of electron acceptors in promoting anaerobic oxidation of methane (AOM) in the sediments of boreal lakes is currently unknown. Here, we studied the AOM rate of sediment slurries collected from three profundal stations of a nitrate-rich, oligo-mesotrophic, boreal lake (Lake Pääjärvi, Finland), under varying nitrate concentrations using 13C-labelling. Furthermore, vertical profiles of the sediment and porewater geochemistry, and the microbial communities (16S rRNA gene and shotgun metagenomic sequencing) were analyzed. Despite geochemical data indicating that simultaneous consumption of nitrate and methane took place at the sediment layers chosen for incubations, AOM rate…
Effects of tilling methods on soil penetration resistance, organic carbon and water stable aggregates in a vineyard of semiarid Mediterranean environ…
2018
Tillage, especially in semiarid Mediterranean environment, enhances the mineralization process of soil organic matter (SOM) and, in turn, decreases aggregate stability. Furthermore, continuous tillage leads to the formation of plough pan beneath the tilled layer. In the present study, we investigated the effect of an innovative self-propelled machine (spading machine, SM) for shallow tillage on SOM, water stable aggregates (WSA) and soil penetration resistance (PR). Such effects were compared to those of chisel plough (CP), rotary tiller (RT) and no tillage (NT). Each tilling method was applied up to a depth of 15 cm, whereas in NT only a brush cutter was used for weed control. Soil analyse…
Influence of plant traits, soil microbial properties, and abiotic parameters on nitrogen turnover of grassland ecosystems
2016
International audience; Although it is known that multiple interactions among plant functional traits, microbial properties , and abiotic soil parameters influence the nutrient turnover, the relative contribution of each of these groups of variables is poorly understood. We manipulated grassland plant functional composition and soil nitrogen (N) availability in a multisite mesocosm experiment to quantify their relative effects on soil N turnover. Overall, root traits, arbuscular mycorrhizal colonization, denitrification potential, as well as N availability and water availability, best explained the variation in measured ecosystem properties, especially the trade-off between nutrient sequest…
Les phénols de la lignine et le 13C, traceurs de l'origine des matières organiques du sol
2001
Abstract In spodosols of Gascony (France), conversion of maritime pine stands into maize cropping leads to an incorporation of maize organic matter, which changed the isotopic (δ13C) and phenolic signature in A and L horizons of soil. Hydrolysis of phenol lignin in forests and cultivated soils showed the predominance of vanillic units under forest and the early but moderate incorporation of cinnamic acids. Incorporation of syringic units appeared higher, related to a large maize production of stable syringic phenols. Syringic units represented a long-term marker of maize inputs in soils, whereas vanillic units revealed the degradation of forest organic matter.
Non-hydrolysable macromolecular constituents from outer walls of Chlorella fusca and Nanochlorum eucaryotum
1992
Abstract Many green microalgae possess a thin trilaminar outer wall (TLS) with a very high resistance to chemical degradation. TLS are known to play an important protective role in living cells. They are also selectively preserved during fossilization and thus provide a major contribution to the fossil organic matter of a number of sedimentary rocks. However, little information is available on TLS chemical structure. Examination of the TLS of Chlorella fusca (a lacustrine Chlorophycea) and of Nanochlorum eucaryotum (a recently discovered marine Chlorophycea) indicated that (i) they exhibit morphological features commonly observed in other green microalgae, (ii) their non-hydrolysable macrom…
Iron and pH regulating the photochemical mineralization of dissolved organic carbon
2017
Solar radiation mineralizes dissolved organic matter (DOM) to dissolved inorganic carbon through photochemical reactions (DIC photoproduction) that are influenced by iron (Fe) and pH. This study addressed as to what extent Fe contributes to the optical properties of the chromophoric DOM (CDOM) and DIC photoproduction at different pH values. We created the associations of Fe and DOM (Fe-DOM) that cover the range of loadings of Fe on DOM and pH values found in freshwaters. The introduced Fe enhanced the light absorption by CDOM independent of pH. Simulated solar irradiation decreased the light absorption by CDOM (i.e., caused photobleaching). Fe raised the rate of photobleaching and steepened…
Use of biological and sedimentation models for designing Peñíscola WWTP.
2004
This paper presents Peñíscola wastewater treatment plant design. Peñíscola is a tourist city in Castellón (Spain), whose population changes significantly between summer and the rest of the year. The design of the biological and settling treatment units has been confirmed by computer model simulations and provided for biological organic matter, nitrogen and phosphorus removal. Two different treatment schemes have been proposed in order to optimize the plant performance during both seasonal operations. During low-load season, the plant will be operated under extended aeration conditions, so further sludge stabilization will not be needed. During high-load season, the plant will be operated un…
Characterization of Humic Acids from Raised Bog Peat
2014
Abstract Humic substances form most of the organic component of soil, peat and natural waters, but their structure and properties are very much dependent on the source. The aim of this study was to characterize humic acids from raised bog peat to evaluate the homogeneity of humic acids isolated from the bog bodies and to study peat humification impact on the properties of humic acids. Peat humic acids (HA) have an intermediate position between the living organic matter and coal organic matter, with their structure formed in a process where the relatively labile moieties (carbohydrates, amino acids, etc.) are destroyed, and thermodynamically more stable aromatic and polycyclic structures eme…
Effects of length and application rate of rice straw mulch on surface runoff and soil loss under laboratory simulated rainfall
2021
Abstract Forest land affected by deforestation yields high soil and water losses. Suitable management practices need to be found that can reduce these losses and achieve ecological and hydrological sustainability of the deforested areas. Mulch has been found to be effective in reducing soil losses; straw mulch is easy to apply, contributes soil organic matter, and is efficient since the day of application. However, the complex effects of rice straw mulch with different application rates and lengths on surface runoff and soil loss have not been clarified in depth. The current paper evaluates the efficiency of rice straw mulch in reducing the hydrological response of a silty clay loam soil un…
Fire effects on soil aggregation: A review
2011
Abstract Fire can affect soil properties depending on a number of factors including fire severity and soil type. Aggregate stability (AS) refers to soil structure resilience in response to external mechanical forces. Many authors consider soil aggregation to be a parameter reflecting soil health, as it depends on chemical, physical and biological factors. The response of AS to forest fires is complex, since it depends on how fire has affected other related properties such as organic matter content, soil microbiology, water repellency and soil mineralogy. Opinions differ concerning the effect of fire on AS. Some authors have observed a decrease in AS in soils affected by intense wildfire or …