Sedum alfredii Hance has been identified as zinc(Zn) and cadmium(Cd) co-hyperaccumulator.In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H.were ex...Sedum alfredii Hance has been identified as zinc(Zn) and cadmium(Cd) co-hyperaccumulator.In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H.were examined.The results show that Zn and Cd contents in the shoots of Sedum alfredii H.treated with 1000 μmol/L Zn2+ and/or 200 μmol/L Cd2+ increased linearly within 15 d.Contents of total S,glutathione(GSH) and H2O2 in shoots also increased within 15 d,and then decreased.Total S and GSH contents in shoots were higher under Cd2+ treatment than under Zn2+ treatment.However,reverse trends of H2O2 content in shoots were obtained,in which much higher H2O2 content was observed in Zn2+-treated shoots than in Cd2+-treated shoots.Similarly,the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn2+-treated leaf than in the Cd2+-treated one.These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn2+ and Cd2+ for the hyperaccumulator Sedum alfredii H.And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves.Our results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2.展开更多
In situ capping is an attractive and cost-effective method for remediation of contaminated sediments,but few studies on enhancing contaminant degradation in sediment caps have been reported,especially for chlorinated ...In situ capping is an attractive and cost-effective method for remediation of contaminated sediments,but few studies on enhancing contaminant degradation in sediment caps have been reported,especially for chlorinated benzenes.Electrically enhanced bioactive barrier is a new process for in situ remediation for reducible compounds in soil or sediments.The primary objective of this study is to determine if electrodes in sediment could create a redox gradient and provide electron acceptor/donor to stimulate degradation of chlorinated contaminant.The results demonstrate that graphite electrodes lead to sustainable evolution of hydrogen,displaying zero-order kinetics in the initial stages with different voltages.The constant rates of hydrogen evolution at 3,4,and 5 V are1.05,2.54,and 4.3 nmol·L 1·d 1,respectively.Even higher voltage can produce more hydrogen,but it could not keep long time because the over potentials on electrode surfaces prevent its function.The study shows that 4 V is more appropriate for hydrogen evolution.The measured and evaluated concentration of 1,2,3,5-tetrachlorobenzene in pore water of sediment and concentration of sulfate show that dechlorination is inhibited at higher concentration of sulfate.展开更多
基金Project (Nos. 30630046 and 20777068) supported by the National Natural Science Foundation of China
文摘Sedum alfredii Hance has been identified as zinc(Zn) and cadmium(Cd) co-hyperaccumulator.In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H.were examined.The results show that Zn and Cd contents in the shoots of Sedum alfredii H.treated with 1000 μmol/L Zn2+ and/or 200 μmol/L Cd2+ increased linearly within 15 d.Contents of total S,glutathione(GSH) and H2O2 in shoots also increased within 15 d,and then decreased.Total S and GSH contents in shoots were higher under Cd2+ treatment than under Zn2+ treatment.However,reverse trends of H2O2 content in shoots were obtained,in which much higher H2O2 content was observed in Zn2+-treated shoots than in Cd2+-treated shoots.Similarly,the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn2+-treated leaf than in the Cd2+-treated one.These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn2+ and Cd2+ for the hyperaccumulator Sedum alfredii H.And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves.Our results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2.
基金Supported by the National Natural Science Foundation of China（51108317） the Municipal Natural Science Foundation of Tianjin（12JCQNJC05400）
文摘In situ capping is an attractive and cost-effective method for remediation of contaminated sediments,but few studies on enhancing contaminant degradation in sediment caps have been reported,especially for chlorinated benzenes.Electrically enhanced bioactive barrier is a new process for in situ remediation for reducible compounds in soil or sediments.The primary objective of this study is to determine if electrodes in sediment could create a redox gradient and provide electron acceptor/donor to stimulate degradation of chlorinated contaminant.The results demonstrate that graphite electrodes lead to sustainable evolution of hydrogen,displaying zero-order kinetics in the initial stages with different voltages.The constant rates of hydrogen evolution at 3,4,and 5 V are1.05,2.54,and 4.3 nmol·L 1·d 1,respectively.Even higher voltage can produce more hydrogen,but it could not keep long time because the over potentials on electrode surfaces prevent its function.The study shows that 4 V is more appropriate for hydrogen evolution.The measured and evaluated concentration of 1,2,3,5-tetrachlorobenzene in pore water of sediment and concentration of sulfate show that dechlorination is inhibited at higher concentration of sulfate.
