Application of enriched stable isotope technique to the study of copper bioavailability in Daphnia magna  

作　　者：Wenhong Fan Chenguang WU Chunmei Zhao Tao Yu Yuan Zhang 

机构地区：[1]Department of Environmental Science and Engineering, School of Chemistry and Environment, Beihang University, Beijing 100191, China. E-mail: fanwh @ buaa. edu. cn [2]Chinese Research Academy of Environmental Sciences, Beijing 100012, China

出　　处：《Journal of Environmental Sciences》2011年第5期831-836,共6页环境科学学报（英文版）

基　　金：supported by the National Basic Research Program of China "Water Environmental Quality Evolution and Water Quality Criteria in Lakes" (No.2008CB418201);the National Natural Science Foundation of China (No. 40871215);the Natural Science Foundation of Beijing (No. 8092019)

摘　　要：The biokinetics of Cu in Daphnia magna, including dissolved uptake, assimilation and efflux, has been determined using a gamma 67^Cu radiotracer methodology. However, this gamma emitting radioisotope is not readily available due to its very short half-life. In the present study, we employed a stable isotope tracer （65^Cu） to determine the Cu biokinetics and compared our results to those determined using 67^Cu. The dissolved uptake rate constant of 65^Cu was 3.36 L/（g.day）, which is higher than that of 67^Cu （1.32 L/（g.day））. With increasing food concentrations from 2×10^4 to 1×10^5 cells/mL, the Cu assimilation efficiency （AE） decreased from 46% to 11%, compared to a decrease from 27% to 16% when determined using 67^Cu. The effiux of Cu from Daphnia magna was quantified following both dissolved and dietary uptake. The efflux of waterborne Cu was comparable to that of dietborne Cu and the effiux rate constant （0.32-0.52 day^-l） was higher than that determined by 67^Cu （0.19-0.20 day^-1）. By considering different water properties and handling procedure between the two experiments, we believe that these differences are reasonable. Overall, this study demonstrated that the enriched stable isotope tracer technique is a powerful tool to investigate metal bioavailability and maybe a good alternative to radioactive measurements.The biokinetics of Cu in Daphnia magna, including dissolved uptake, assimilation and efflux, has been determined using a gamma 67^Cu radiotracer methodology. However, this gamma emitting radioisotope is not readily available due to its very short half-life. In the present study, we employed a stable isotope tracer （65^Cu） to determine the Cu biokinetics and compared our results to those determined using 67^Cu. The dissolved uptake rate constant of 65^Cu was 3.36 L/（g.day）, which is higher than that of 67^Cu （1.32 L/（g.day））. With increasing food concentrations from 2×10^4 to 1×10^5 cells/mL, the Cu assimilation efficiency （AE） decreased from 46% to 11%, compared to a decrease from 27% to 16% when determined using 67^Cu. The effiux of Cu from Daphnia magna was quantified following both dissolved and dietary uptake. The efflux of waterborne Cu was comparable to that of dietborne Cu and the effiux rate constant （0.32-0.52 day^-l） was higher than that determined by 67^Cu （0.19-0.20 day^-1）. By considering different water properties and handling procedure between the two experiments, we believe that these differences are reasonable. Overall, this study demonstrated that the enriched stable isotope tracer technique is a powerful tool to investigate metal bioavailability and maybe a good alternative to radioactive measurements.

关 键 词：stable isotope Daphnia magna COPPER BIOAVAILABILITY 

分 类 号：X132[环境科学与工程—环境科学] S859.796[农业科学—临床兽医学]