In order to study the influence of difference in C2H2 concentration on the production of CO2,N2O,NH4-N and volatile fatty acids(VFA).soil slurries with a gradient in C2H2 concentration were anaerobically incubated at...In order to study the influence of difference in C2H2 concentration on the production of CO2,N2O,NH4-N and volatile fatty acids(VFA).soil slurries with a gradient in C2H2 concentration were anaerobically incubated at 25℃ for 2 weeks.Acetate,butyrate and CO2 production and NH4-N accumulation were inhibited in the slurres in the presence of C2H2;and the inhibition effect increased with increasing C2H2 from 0 to 20 kPa in the headspace gas of the incubation bottle.However,N2O,isobutyrate and propionate production was not obviously different among the slurres amended with C2H2 from 2.5 to 20 kPa.Therefore,the results implied that the C2H2 did not promote the inhibition but only increased the side effect on other microbial processes.The C2H2 of 2.5 kPa was suggested to be the optimum choice for the present denitrification study.展开更多
Several studies focused on nutrients have shown that land use and management practices have a strong influence on stream chemistry. Much less is known about the relationship between heavy metal concentrations in strea...Several studies focused on nutrients have shown that land use and management practices have a strong influence on stream chemistry. Much less is known about the relationship between heavy metal concentrations in stream water and land use. We compared the variability of trace element concentrations in the stream of a catchment exposed to different types of management practices and land use. This is a small catchment with previous agricultural diffuse and accidental pollution mainly due to the spreading of slurry. The agricultural land was reforested in July 1998. The concentrations of Fe, Mn, Cu and Zn in dissolved phase from surface water samples collected at the catchment outlet were determined over a period of approximately six years. The results suggest that dissolved metal concentrations, especially Cu and Mn, are controlled by the land use and management practices. The median concentrations of studied metals were the highest in the agricultural period. It was also during this period when they all presented the highest concentration peaks, coinciding with a time of heavy application of manure to the soil. Dissolved Fe and Mn showed high dependence of flow rate, whereas Cu and Zn concentrations seemed to be independent of flow.展开更多
Trichloroethylene （TCE）, as one of the most common chlorinated organic compounds in soils and aquifers at many industrial sites, is carcinogenic and often recalcitrant in environment. TCE degradation in artificially...Trichloroethylene （TCE）, as one of the most common chlorinated organic compounds in soils and aquifers at many industrial sites, is carcinogenic and often recalcitrant in environment. TCE degradation in artificially contaminated soil samples was conducted using Fenton-like processes, i.e., by addition of excess hydrogen peroxide （H2O2）. H2O2 could directly oxidize TCE without addition of ferrous iron in contaminated soil. Under the optimal condition （H2O2 concentration of 300 mg kg^-1, pH at 5.0, and reaction time of 30 rain）, the removal efficiency of TCE in the soil was up to 92.3%. When the initial TCE concentration increased from 30 to 480 mg kg^-1 in soil, the TCE removal rates varied from 89.2% to 86.6%; while the residual TCE in soil ranged from 2.28 to 47.57 mg kg^-1. Results from successive oxidations showed that the TCE removal rate with the TCE concentration of 180 mg kg^-1 increased slightly from 91.6% to 96.2% as the number of successive oxidation cycle increased from one to four. Therefore, increasing the frequency of H2O2 oxidation was perhaps a feasible way to increase TCE removal rate for TCE-contaminated soil.展开更多
A two-liquid-phase （TLP） soil slurry system was employed to quantify the efficiencies of autoclaving and mercuric chloride sterilization in the dissipation of polycyclic aromatic hydrocaxbons （PAHs）. The fates of ...A two-liquid-phase （TLP） soil slurry system was employed to quantify the efficiencies of autoclaving and mercuric chloride sterilization in the dissipation of polycyclic aromatic hydrocaxbons （PAHs）. The fates of 11 PAHs （naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo（a）anthracene, benzo（a）pyrene, benzo（b）fluoranthene, benzo（k）fluoranthene, dibenzo（a, h）anthracene） were recorded over 113 days of incubation. No microorganisms were detected in the HgC12-sterilized soil slurries during the whole incubation period, indicating very effective sterilization. However, about 2% 36% losses of PAHs were observed in the HgCl2- sterilized slurry. In contrast to the HgCl2-sterilized soil slurry, some microorganisms survived in the autoclaved soil slurries. Moreover, significant biodegradiation of 6 PAHs （naphthalene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene） was observed in the autoclaved soil slurries. This indicated that biodegradation results of PAHs in the soil slurries, calculated on basis of the autoclaved control, would be underestimated. It could be concluded that the sterilization efficiency and effectiveness of HgCl2 on soil slurry was much higher than those of autoclaving at 121 ℃ for 45 rain.展开更多
文摘In order to study the influence of difference in C2H2 concentration on the production of CO2,N2O,NH4-N and volatile fatty acids(VFA).soil slurries with a gradient in C2H2 concentration were anaerobically incubated at 25℃ for 2 weeks.Acetate,butyrate and CO2 production and NH4-N accumulation were inhibited in the slurres in the presence of C2H2;and the inhibition effect increased with increasing C2H2 from 0 to 20 kPa in the headspace gas of the incubation bottle.However,N2O,isobutyrate and propionate production was not obviously different among the slurres amended with C2H2 from 2.5 to 20 kPa.Therefore,the results implied that the C2H2 did not promote the inhibition but only increased the side effect on other microbial processes.The C2H2 of 2.5 kPa was suggested to be the optimum choice for the present denitrification study.
文摘Several studies focused on nutrients have shown that land use and management practices have a strong influence on stream chemistry. Much less is known about the relationship between heavy metal concentrations in stream water and land use. We compared the variability of trace element concentrations in the stream of a catchment exposed to different types of management practices and land use. This is a small catchment with previous agricultural diffuse and accidental pollution mainly due to the spreading of slurry. The agricultural land was reforested in July 1998. The concentrations of Fe, Mn, Cu and Zn in dissolved phase from surface water samples collected at the catchment outlet were determined over a period of approximately six years. The results suggest that dissolved metal concentrations, especially Cu and Mn, are controlled by the land use and management practices. The median concentrations of studied metals were the highest in the agricultural period. It was also during this period when they all presented the highest concentration peaks, coinciding with a time of heavy application of manure to the soil. Dissolved Fe and Mn showed high dependence of flow rate, whereas Cu and Zn concentrations seemed to be independent of flow.
基金Supported by the Ministry of Environmental Protection of China(No.201109020)
文摘Trichloroethylene （TCE）, as one of the most common chlorinated organic compounds in soils and aquifers at many industrial sites, is carcinogenic and often recalcitrant in environment. TCE degradation in artificially contaminated soil samples was conducted using Fenton-like processes, i.e., by addition of excess hydrogen peroxide （H2O2）. H2O2 could directly oxidize TCE without addition of ferrous iron in contaminated soil. Under the optimal condition （H2O2 concentration of 300 mg kg^-1, pH at 5.0, and reaction time of 30 rain）, the removal efficiency of TCE in the soil was up to 92.3%. When the initial TCE concentration increased from 30 to 480 mg kg^-1 in soil, the TCE removal rates varied from 89.2% to 86.6%; while the residual TCE in soil ranged from 2.28 to 47.57 mg kg^-1. Results from successive oxidations showed that the TCE removal rate with the TCE concentration of 180 mg kg^-1 increased slightly from 91.6% to 96.2% as the number of successive oxidation cycle increased from one to four. Therefore, increasing the frequency of H2O2 oxidation was perhaps a feasible way to increase TCE removal rate for TCE-contaminated soil.
基金Supported by the National High Technology Research and Development Program (863 Program) of China (No. 2007AA061101)the National Natural Science Foundation of China (Nos. 20707028,4092106,40771104 and 40701078)
文摘A two-liquid-phase （TLP） soil slurry system was employed to quantify the efficiencies of autoclaving and mercuric chloride sterilization in the dissipation of polycyclic aromatic hydrocaxbons （PAHs）. The fates of 11 PAHs （naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo（a）anthracene, benzo（a）pyrene, benzo（b）fluoranthene, benzo（k）fluoranthene, dibenzo（a, h）anthracene） were recorded over 113 days of incubation. No microorganisms were detected in the HgC12-sterilized soil slurries during the whole incubation period, indicating very effective sterilization. However, about 2% 36% losses of PAHs were observed in the HgCl2- sterilized slurry. In contrast to the HgCl2-sterilized soil slurry, some microorganisms survived in the autoclaved soil slurries. Moreover, significant biodegradiation of 6 PAHs （naphthalene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene） was observed in the autoclaved soil slurries. This indicated that biodegradation results of PAHs in the soil slurries, calculated on basis of the autoclaved control, would be underestimated. It could be concluded that the sterilization efficiency and effectiveness of HgCl2 on soil slurry was much higher than those of autoclaving at 121 ℃ for 45 rain.
