The Experts below are selected from a list of 12813 Experts worldwide ranked by ideXlab platform
Pierre Marmonier - One of the best experts on this subject based on the ideXlab platform.
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water sediment exchanges control microbial processes associated with leaf litter degradation in the hyporheic zone a Microcosm Study
Microbial Ecology, 2011Co-Authors: Pierre Marmonier, Simon Navel, Florian Mermillodblondin, Bernard Montuelle, Eric Chauvet, Laurent SimonAbstract:The present Study aimed to experimentally quantify the influence of a reduction of surface sediment permeability on microbial characteristics and ecological processes (respiration and leaf litter decomposition) occurring in the hyporheic zone (i.e. the sedimentary interface between surface water and groundwater). The physical structure of the water-sediment interface was manipulated by adding a 2-cm layer of coarse sand (unclogged systems) or fine sand (clogged systems) at the sediment surface of slow filtration columns filled with a heterogeneous gravel/sand sedimentary matrix. The influence of clogging was quantified through measurements of hydraulic conductivity, water chemistry, microbial abundances and activities and associated processes (decomposition of alder leaf litter inserted at a depth of 9 cm in sediments, oxygen and nitrate consumption by microorganisms). Fine sand deposits drastically reduced hydraulic conductivity (by around 8-fold in comparison with unclogged systems topped by coarse sand) and associated water flow, leading to a sharp decrease in oxygen (reaching less than 1 mg L(-1) at 3 cm depth) and nitrate concentrations with depth in sediments. The shift from aerobic to anaerobic conditions in clogged systems favoured the establishment of denitrifying bacteria living on sediments. Analyses performed on buried leaf litter showed a reduction by 30% of organic matter decomposition in clogged systems in comparison with unclogged systems. This reduction was linked to a negative influence of clogging on the activities and abundances of leaf-associated microorganisms. Finally, our Study clearly demonstrated that microbial processes involved in organic matter decomposition were dependent on hydraulic conductivity and oxygen availability in the hyporheic zone.
Ravi Naidu - One of the best experts on this subject based on the ideXlab platform.
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bioavailability of weathered hydrocarbons in engine oil contaminated soil impact of bioaugmentation mediated by pseudomonas spp on bioremediation
Science of The Total Environment, 2018Co-Authors: Kavitha Ramadass, Mallavarapu Megharaj, Kadiyala Venkateswarlu, Ravi NaiduAbstract:Abstract Heavier fraction hydrocarbons (C15-C36) formed in soil after biotic and abiotic weatherings of engine oil are the continuing constraints in the bioremediation strategy, and their bioavailability remains a poorly quantified regulatory factor. In a Microcosm Study, we used two strains of Pseudomonas, P. putida TPHK-1 and P. aeruginosa TPHK-4, in strategies of bioremediation, viz., natural attenuation, biostimulation and bioaugmentation, for removal of weathered total petroleum hydrocarbons (TPHs) in soil contaminated long-term with high concentrations of engine oil (39,000–41,000 mg TPHs kg−1 soil). Both the bacterial strains exhibited a great potential in remediating weathered hydrocarbons of engine oil. Addition of inorganic fertilizers (NPK), at recommended levels for bioremediation, resulted in significant inhibition in biostimulation/enhanced natural attenuation as well as bioaugmentation. The data on dehydrogenase activity clearly confirmed those of bioremediation strategies used, indicating that this enzyme assay could serve as an indicator of bioremediation potential of oil-contaminated soil. Extraction of TPHs from engine oil-contaminated soil with hydroxypropyl-β-cyclodextrin (HPCD), but not 1-butanol, was found reliable in predicting the bioavailability of weathered hydrocarbons. Also, 454 pyrosequencing data were in accordance with those of bioremediation strategies used in the present Microcosm Study, suggesting the possible use of pyrosequencing in designing approaches for bioremediation.
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assessment of metal toxicity and bioavailability in metallophyte leaf litters and metalliferous soils using eisenia fetida in a Microcosm Study
Ecotoxicology and Environmental Safety, 2016Co-Authors: Ramkrishna Nirola, Mallavarapu Megharaj, Kadiyala Venkateswarlu, Rupak Aryal, Ray Correll, Ravi NaiduAbstract:The leaf litters of tree species, Acacia pycnantha (Ap) and Eucalyptus camaldulensis (Ec), predominantly growing at an abandoned copper (Cu) mine and mine soils including controls, were assessed for determining the metal toxicity and bioavailability using earthworm species Eisenia fetida, in a Microcosm. Significant reduction in body weight as well as mortality were observed when the worms were introduced into mine soil or its combination with mine Ap litter. Virtually, there were no juveniles when the worms were fed on substratum that contained mine soil or mine leaf litter. The extent of bioaccumulation was dependent on water-soluble fraction of a metal in soil. The accumulation of cadmium, lead and copper in worm tissue was significantly more in treatments that received mine soil with or without mine leaf litter. However, the tissue concentration of zinc did not differ much in earthworms irrespective of its exposure to control or contaminated samples. Mine leaf litter from Ec, a known Cu hyperaccumulator, was more hospitable to earthworm survival and juvenile than that of Ap litter. Validation of the data on bioaccumulation of metals indicated that the mine leaf litter significantly contributed to metal bioavailability. However, it was primarily the metal concentration in mine soil that was responsible for earthworm toxicity and bioavailability. Our data also indicate that detrivores like earthworm is greatly responsible for heavy metal transfer from mines into the ecosystem.
T.c. Bora - One of the best experts on this subject based on the ideXlab platform.
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Bioremediation potential of native hydrocarbon degrading bacterial strains in crude oil contaminated soil under Microcosm Study
International Biodeterioration & Biodegradation, 2014Co-Authors: Abhijit Sarma Roy, Reshita Baruah, Maina Borah, Anil Kumar Singh, Hari Prasanna Deka Boruah, Neelima Saikia, Manab Deka, Nipu Dutta, T.c. BoraAbstract:Bioremediation of crude oil contaminated soil is an effective process to clean petroleum contaminant from the environment. In this Study, we isolated 39 native crude oil degrading bacteria from different crude oil contaminated soils. From 16S rDNA sequences, we confirmed that the isolated bacteria belong to the genera Lysinibacillus, Brevibacillus, Bacillus, Paenibacillus, Stenotrophomonas, Alcaligenes, Delftia, Achromobacter and Pseudomonas. Four most effective strains (designated as AS03, N108, N002 and N78) were used for batch culture and Microcosm evaluation. Gas chromatography analysis, further confirmed that the strain AS03, N108, N002 and N78 were able to degrade crude oil under both shake culture and Microcosm Study. Under Microcosm, the soil quality was further improved significantly in the treatments of BF1-Mix (N108-AS03) and BF2-Mix (N002-N78). The improvement of soil quality was also confirmed by earthworm mortality bioassay and in plant test on rice (Oryza sativa) and mung (Vigna radiata). These findings demonstrated that the combine use of crude oil degrading bacteria along with nutrient supplements could revive crude oil contaminated soil effectively in large scale.
Diyu Zhang - One of the best experts on this subject based on the ideXlab platform.
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The effect of soil organic matter on fate of polycyclic aromatic hydrocarbons in soil: A Microcosm Study.
Environmental Pollution, 2010Co-Authors: Yu Yang, Shu Tao, Na Zhang, Diyu ZhangAbstract:A Microcosm Study was conducted to address the influences of air-soil partition and sequestration on the fate of polycyclic aromatic hydrocarbons (PAHs) in soil. Sterilized and unsterilized soils with soil organic carbon (SOC) content ranging from 0.23 to 7.06% were incubated in a chamber with six PAHs supplied through air. After 100 d of incubation when the system approached pseudo-steady state, the PAHs concentrations in the unsterilized soils still correlated with SOC significantly, while the association did not exist for those sterilized. The lower degradation rate in the soil with higher SOC was likely the major reason for the association between SOC and PAHs concentrations, while the decreased surface porosity likely suppressed such correlation for the sterilized samples. The results indicated that the sequestration was likely the major mechanism for the accumulation of PAHs in soils, while both of the soil porosity and PAHs properties had observed influences.
Simon Navel - One of the best experts on this subject based on the ideXlab platform.
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water sediment exchanges control microbial processes associated with leaf litter degradation in the hyporheic zone a Microcosm Study
Microbial Ecology, 2011Co-Authors: Pierre Marmonier, Simon Navel, Florian Mermillodblondin, Bernard Montuelle, Eric Chauvet, Laurent SimonAbstract:The present Study aimed to experimentally quantify the influence of a reduction of surface sediment permeability on microbial characteristics and ecological processes (respiration and leaf litter decomposition) occurring in the hyporheic zone (i.e. the sedimentary interface between surface water and groundwater). The physical structure of the water-sediment interface was manipulated by adding a 2-cm layer of coarse sand (unclogged systems) or fine sand (clogged systems) at the sediment surface of slow filtration columns filled with a heterogeneous gravel/sand sedimentary matrix. The influence of clogging was quantified through measurements of hydraulic conductivity, water chemistry, microbial abundances and activities and associated processes (decomposition of alder leaf litter inserted at a depth of 9 cm in sediments, oxygen and nitrate consumption by microorganisms). Fine sand deposits drastically reduced hydraulic conductivity (by around 8-fold in comparison with unclogged systems topped by coarse sand) and associated water flow, leading to a sharp decrease in oxygen (reaching less than 1 mg L(-1) at 3 cm depth) and nitrate concentrations with depth in sediments. The shift from aerobic to anaerobic conditions in clogged systems favoured the establishment of denitrifying bacteria living on sediments. Analyses performed on buried leaf litter showed a reduction by 30% of organic matter decomposition in clogged systems in comparison with unclogged systems. This reduction was linked to a negative influence of clogging on the activities and abundances of leaf-associated microorganisms. Finally, our Study clearly demonstrated that microbial processes involved in organic matter decomposition were dependent on hydraulic conductivity and oxygen availability in the hyporheic zone.