Norfloxacin sorption and the factors （soil organic matter （SOM）, pH, and exogenous copper （Cu） influencing the sorption were investigated in a black soil （soil B）, a fluvo-aquic soil （soil F）, and a red soil ...Norfloxacin sorption and the factors （soil organic matter （SOM）, pH, and exogenous copper （Cu） influencing the sorption were investigated in a black soil （soil B）, a fluvo-aquic soil （soil F）, and a red soil （soil R）. With increasing norfloxacin concentrations, sorption amount of norfloxacin increased in both the bulk soils and their SOM-removed soils, but the sorption capacity of SOM-removed soils was higher than that of their corresponding bulk soils, indicating that the process of norfloxacin sorption in soil was influenced by the soil properties including SOM. The sorption data in all bulk soils and SOM-removed soils were fitted to Freundlich and Langmuir models. The correlation coefficients suggested that the experimental data fitted better to Freundlich equation than to Langmuir equation. Furthermore, the data from soil F and SOM-removed F could not be described by Langmuir equation. The norfloxacin sorption amount decreased in soil B and soil F, whereas it increased in soil R as solution pH increased. The maximum KD and Koc were achieved in soil R when the equilibrium solution pH was 6. The norfloxacin sorption was also influenced by the exogenous Cu^2＋, which depended on the soil types and Cu^2＋ concentrations. With increasing Cu^2＋ concentrations in solution, generally, sorption amount, KD and Koc for norfloxacin in soils increased and were up to a peak at 100 mg/L Cu^2＋, and then the sorption amount decreased regardless of norfloxacin levels.展开更多
Mixed or chloride salty ions dominate in saline soils, and exert wide-ranging adversely affect on soil biological processes and soil functions. The objectives of this study were to（1） explore the impacts of mixed（0...Mixed or chloride salty ions dominate in saline soils, and exert wide-ranging adversely affect on soil biological processes and soil functions. The objectives of this study were to（1） explore the impacts of mixed（0, 3, 6, 10, 20 and 40 g Cl–/SO42–salt/kg dry soil） and chloride（0, 1.5, 3, 5, 8 and 15 g Cl– salt/kg dry soil） salts on soil enzyme activities, soil physiological functional（Biolog） profiles and microbial community structure by using soil enzymatic, Biolog-Eco microplates as well as denaturing gradient gel electrophoresis（DEEG） methods, and（2） determine the threshold concentration of soil electronic conductivity（EC1：5） on maintaining the functional and structural diversity of soil microbial community. The addition of either Cl– or mixed Cl–/SO42–salt obviously increased soil EC, but adversely affected soil biological activities including soil invertase activity, soil microbial biomass carbon（MBC） and substrate-induced respiration（SIR）. Cl– salt showed a greater deleterious influence than mixed Cl–/SO42–salt on soil enzymes and MBC, e.g., the higher soil MBC consistently appeared with Cl–/SO42–instead of Cl– treated soil. Meanwhile, we found that SIR was more reliable than soil basal respiration（SBR） on explaining the changes of soil biological activity responsive to salt disturbance. In addition, microbial community structures of the soil bacteria, fungi, and Bacillus were obviously affected by both salt types and soil EC levels, and its diversity increased with increasing of mixed Cl–/SO42–salt rates, and then sharply declined down after it reached critical point. Moreover, the diversity of fungal community was more sensitive to the mixed salt addition than other groups. The response of soil physiological profiles（Biolog） followed a dose-response pattern with Cl–（R2=0.83） or mixed Cl–/SO42–（R2=0.89） salt. The critical threshold concentrations of salts for soil physiological function were 0.45 d S/m for Cl– and 1.26 d S/m for Cl–/SO42–, and those for soil microbial community structural diversity were 0.70 d S/m for Cl– and 1.75 d S/m for Cl–/SO42–.展开更多
基金supported by the National Key Basic Research Support Foundation of China (No.2005CB121105), the Ministry of Science and Technology of China (No. 2006BAD05B05)the International Foundation for Science (No. C/4076).
文摘Norfloxacin sorption and the factors （soil organic matter （SOM）, pH, and exogenous copper （Cu） influencing the sorption were investigated in a black soil （soil B）, a fluvo-aquic soil （soil F）, and a red soil （soil R）. With increasing norfloxacin concentrations, sorption amount of norfloxacin increased in both the bulk soils and their SOM-removed soils, but the sorption capacity of SOM-removed soils was higher than that of their corresponding bulk soils, indicating that the process of norfloxacin sorption in soil was influenced by the soil properties including SOM. The sorption data in all bulk soils and SOM-removed soils were fitted to Freundlich and Langmuir models. The correlation coefficients suggested that the experimental data fitted better to Freundlich equation than to Langmuir equation. Furthermore, the data from soil F and SOM-removed F could not be described by Langmuir equation. The norfloxacin sorption amount decreased in soil B and soil F, whereas it increased in soil R as solution pH increased. The maximum KD and Koc were achieved in soil R when the equilibrium solution pH was 6. The norfloxacin sorption was also influenced by the exogenous Cu^2＋, which depended on the soil types and Cu^2＋ concentrations. With increasing Cu^2＋ concentrations in solution, generally, sorption amount, KD and Koc for norfloxacin in soils increased and were up to a peak at 100 mg/L Cu^2＋, and then the sorption amount decreased regardless of norfloxacin levels.
基金supported by the National Key Technologies Research and Development Program(2016YFC0501404)the National Natural Science Foundation of China(41461064)
文摘Mixed or chloride salty ions dominate in saline soils, and exert wide-ranging adversely affect on soil biological processes and soil functions. The objectives of this study were to（1） explore the impacts of mixed（0, 3, 6, 10, 20 and 40 g Cl–/SO42–salt/kg dry soil） and chloride（0, 1.5, 3, 5, 8 and 15 g Cl– salt/kg dry soil） salts on soil enzyme activities, soil physiological functional（Biolog） profiles and microbial community structure by using soil enzymatic, Biolog-Eco microplates as well as denaturing gradient gel electrophoresis（DEEG） methods, and（2） determine the threshold concentration of soil electronic conductivity（EC1：5） on maintaining the functional and structural diversity of soil microbial community. The addition of either Cl– or mixed Cl–/SO42–salt obviously increased soil EC, but adversely affected soil biological activities including soil invertase activity, soil microbial biomass carbon（MBC） and substrate-induced respiration（SIR）. Cl– salt showed a greater deleterious influence than mixed Cl–/SO42–salt on soil enzymes and MBC, e.g., the higher soil MBC consistently appeared with Cl–/SO42–instead of Cl– treated soil. Meanwhile, we found that SIR was more reliable than soil basal respiration（SBR） on explaining the changes of soil biological activity responsive to salt disturbance. In addition, microbial community structures of the soil bacteria, fungi, and Bacillus were obviously affected by both salt types and soil EC levels, and its diversity increased with increasing of mixed Cl–/SO42–salt rates, and then sharply declined down after it reached critical point. Moreover, the diversity of fungal community was more sensitive to the mixed salt addition than other groups. The response of soil physiological profiles（Biolog） followed a dose-response pattern with Cl–（R2=0.83） or mixed Cl–/SO42–（R2=0.89） salt. The critical threshold concentrations of salts for soil physiological function were 0.45 d S/m for Cl– and 1.26 d S/m for Cl–/SO42–, and those for soil microbial community structural diversity were 0.70 d S/m for Cl– and 1.75 d S/m for Cl–/SO42–.
