Through the Fenton pre-oxidation followed by microbial degradation,this study gave full play to its advantages while avoiding its shortcomings for the remediation of crude oil contaminated soil.The Fenton reagent coup...Through the Fenton pre-oxidation followed by microbial degradation,this study gave full play to its advantages while avoiding its shortcomings for the remediation of crude oil contaminated soil.The Fenton reagent coupled with different volumes of H2O2 was applied to the oil contaminated soil and then the microbial agents were introduced to biodegrade the residual oil for 15 days.The correlation between the characteristics of residual oil in soil,the changes in soil physical-chemical property after the Fenton pre-oxidation,and the biodegradation were analyzed in this paper.The results show that the above factors are strongly correlated with the subsequent biodegradation rate,and the order of correlation is as follows:the ratio of TOC to NH4+-N(R^2=0.9513)>the ratio of light oil components to the heavy oil components(R^2=0.9095)>the proportion of hydrocarbons with carbon chain number of less than C23(R^2=0.8259)>the crude oil content(R^2=0.7603)>the soil pH(R^2=0.7492)>the number of microorganisms(R^2=0.6506).During the biodegradation and pre-oxidation reactions of heavy oil components,an appropriate C:N ratio turns out to be the most critical factor in this study.展开更多
The degradation of U-14C-lindane in two Egyptian soils was determined in a three-month laboratory incubation. Lindane mineralization was slow and limited in both soils. Evolution of 14CO2 increased with time but only ...The degradation of U-14C-lindane in two Egyptian soils was determined in a three-month laboratory incubation. Lindane mineralization was slow and limited in both soils. Evolution of 14CO2 increased with time but only reached 3. 5 to 5. 5 % of the initial 14C-concentration within 90 days. At that time both soils contained about 88 % of the applied radiocarbon; 33 % to 37% of the initial dose was unextractable and assumed bound to the soils. The methanol-ex-tractable 14C primarily contained lindane with traces of minor metabolites. Radiorespirometry was used to eva1uate the effect of lindane on soil microbial activity. Low concentrations of the insecticide initially supressed 14CO2 evolution from U-14C-glucose and microbial activity was significantly inhibited by 10 mg lindane/kg soil.展开更多
The Qinghai-Tibet Plateau(QTP)distributes the largest extent of high-altitude mountain permafrost in the world(Zou et al.,2017),which has different characteristics from high-latitude permafrost(Yang et al.,2010)and st...The Qinghai-Tibet Plateau(QTP)distributes the largest extent of high-altitude mountain permafrost in the world(Zou et al.,2017),which has different characteristics from high-latitude permafrost(Yang et al.,2010)and stores massive soil carbon.展开更多
Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs...Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.展开更多
Rangeland degradation is a serious problem throughout sub-Saharan Africa and its restoration is a challenge for the management of arid and semi-arid areas. In Lake Baringo Basin of Kenya, communities and individual fa...Rangeland degradation is a serious problem throughout sub-Saharan Africa and its restoration is a challenge for the management of arid and semi-arid areas. In Lake Baringo Basin of Kenya, communities and individual farmers are restoring indigenous vegetation inside enclosures in an effort to combat severe land degradation and address their livelihood problems. This study evaluated the impact of enclosure management on soil properties and microbial biomass, being key indicators of soil ecosystem health. Six reseeded communal enclosures using soil embankments as water-harvesting structures and strictly regulated access were selected, varying in age from 13 to 23 years. In six private enclosures, ranging from 3 to 17 years in age, individual farmers emulated the communal enclosure strategy and restored areas for their exclusive use. Significant decreases in bulk density, and increases in the soil organic carbon, total nitrogen and microbial biomass contents and stocks were found in the enclosures as compared with the degraded open rangeland. In the private enclosures, the impact of rehabilitation on the soil quality was variable, and soil quality was in general lower than that obtained under communal management. The significant increase of absolute stocks of carbon, nitrogen and microbial biomass compared to the degraded open rangeland indicates the potential for the restoration of soil quality through range rehabilitation. Over-sowing with indigenous legume fodder species could improve total nitrogen content in the soil and nutritional value of the pastures as well.展开更多
As one typical cationic disinfectant, quaternary ammonium compounds(QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the sur...As one typical cationic disinfectant, quaternary ammonium compounds(QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the surrounding environment. Concerningly, it is still unclear how the soil microbial community succession happens and the nitrogen(N)cycling processes alter when exposed to QACs. In this study, one common QAC(benzalkonium chloride(BAC) was selected as the target contaminant, and its effects on the temporal changes in soil microbial community structure and nitrogen transformation processes were determined by q PCR and 16S r RNA sequencing-based methods. The results showed that the aerobic microbial degradation of BAC in the two different soils followed first-order kinetics with a half-life(4.92 vs. 17.33 days) highly dependent on the properties of the soil. BAC activated the abundance of N fixation gene(nif H) and nitrification genes(AOA and AOB) in the soil and inhibited that of denitrification gene(nar G). BAC exposure resulted in the decrease of the alpha diversity of soil microbial community and the enrichment of Crenarchaeota and Proteobacteria. This study demonstrates that BAC degradation is accompanied by changes in soil microbial community structure and N transformation capacity.展开更多
基金supported by the Basic Research Project of the Institute of Hydrogeology and Environmental Geology of the Chinese Academy of Geological Sciences (SK201502)
文摘Through the Fenton pre-oxidation followed by microbial degradation,this study gave full play to its advantages while avoiding its shortcomings for the remediation of crude oil contaminated soil.The Fenton reagent coupled with different volumes of H2O2 was applied to the oil contaminated soil and then the microbial agents were introduced to biodegrade the residual oil for 15 days.The correlation between the characteristics of residual oil in soil,the changes in soil physical-chemical property after the Fenton pre-oxidation,and the biodegradation were analyzed in this paper.The results show that the above factors are strongly correlated with the subsequent biodegradation rate,and the order of correlation is as follows:the ratio of TOC to NH4+-N(R^2=0.9513)>the ratio of light oil components to the heavy oil components(R^2=0.9095)>the proportion of hydrocarbons with carbon chain number of less than C23(R^2=0.8259)>the crude oil content(R^2=0.7603)>the soil pH(R^2=0.7492)>the number of microorganisms(R^2=0.6506).During the biodegradation and pre-oxidation reactions of heavy oil components,an appropriate C:N ratio turns out to be the most critical factor in this study.
文摘The degradation of U-14C-lindane in two Egyptian soils was determined in a three-month laboratory incubation. Lindane mineralization was slow and limited in both soils. Evolution of 14CO2 increased with time but only reached 3. 5 to 5. 5 % of the initial 14C-concentration within 90 days. At that time both soils contained about 88 % of the applied radiocarbon; 33 % to 37% of the initial dose was unextractable and assumed bound to the soils. The methanol-ex-tractable 14C primarily contained lindane with traces of minor metabolites. Radiorespirometry was used to eva1uate the effect of lindane on soil microbial activity. Low concentrations of the insecticide initially supressed 14CO2 evolution from U-14C-glucose and microbial activity was significantly inhibited by 10 mg lindane/kg soil.
基金financially supported by the National Natural Science Foundation of China(41871064)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0304)。
文摘The Qinghai-Tibet Plateau(QTP)distributes the largest extent of high-altitude mountain permafrost in the world(Zou et al.,2017),which has different characteristics from high-latitude permafrost(Yang et al.,2010)and stores massive soil carbon.
基金Project supported by the National High Technology Research and Development Program (863 Program) of China (No.2001AA214191).
文摘Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.
基金the financial support provided by the Flemish Interuniversity Council (VLIR) of Belgium in favour of the first author
文摘Rangeland degradation is a serious problem throughout sub-Saharan Africa and its restoration is a challenge for the management of arid and semi-arid areas. In Lake Baringo Basin of Kenya, communities and individual farmers are restoring indigenous vegetation inside enclosures in an effort to combat severe land degradation and address their livelihood problems. This study evaluated the impact of enclosure management on soil properties and microbial biomass, being key indicators of soil ecosystem health. Six reseeded communal enclosures using soil embankments as water-harvesting structures and strictly regulated access were selected, varying in age from 13 to 23 years. In six private enclosures, ranging from 3 to 17 years in age, individual farmers emulated the communal enclosure strategy and restored areas for their exclusive use. Significant decreases in bulk density, and increases in the soil organic carbon, total nitrogen and microbial biomass contents and stocks were found in the enclosures as compared with the degraded open rangeland. In the private enclosures, the impact of rehabilitation on the soil quality was variable, and soil quality was in general lower than that obtained under communal management. The significant increase of absolute stocks of carbon, nitrogen and microbial biomass compared to the degraded open rangeland indicates the potential for the restoration of soil quality through range rehabilitation. Over-sowing with indigenous legume fodder species could improve total nitrogen content in the soil and nutritional value of the pastures as well.
基金supported by the National Natural Science Foundation of China (No. 42177363)the National Key R&D Program of China (No. 2019YFC1805502)+1 种基金the Open Project of National and Local Joint Engineering Research Center of Shale Gas Exploration and Development (No. YYQKTKFGJDFLHGCYJZX-201904)the Innovation Support Program for Chongqing Overseas Returnees (2017)。
文摘As one typical cationic disinfectant, quaternary ammonium compounds(QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the surrounding environment. Concerningly, it is still unclear how the soil microbial community succession happens and the nitrogen(N)cycling processes alter when exposed to QACs. In this study, one common QAC(benzalkonium chloride(BAC) was selected as the target contaminant, and its effects on the temporal changes in soil microbial community structure and nitrogen transformation processes were determined by q PCR and 16S r RNA sequencing-based methods. The results showed that the aerobic microbial degradation of BAC in the two different soils followed first-order kinetics with a half-life(4.92 vs. 17.33 days) highly dependent on the properties of the soil. BAC activated the abundance of N fixation gene(nif H) and nitrification genes(AOA and AOB) in the soil and inhibited that of denitrification gene(nar G). BAC exposure resulted in the decrease of the alpha diversity of soil microbial community and the enrichment of Crenarchaeota and Proteobacteria. This study demonstrates that BAC degradation is accompanied by changes in soil microbial community structure and N transformation capacity.
