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首页> 外文期刊>Environmental Science & Technology >Cadmium Bioavailability and Accumulation in the Presence of Humic Acid to the Zebra Mussel, Dreissena polymorpha
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Cadmium Bioavailability and Accumulation in the Presence of Humic Acid to the Zebra Mussel, Dreissena polymorpha

机译：腐殖酸存在下斑马贻贝Dreissena polymorpha中镉的生物利用度和累积量

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摘要

Metal speciation in aquatic systems is mainly determined by the type and concentration of ligands present in solution. A very important group of complexing agents is dissolved organic matter (DOM), e.g., humic and fulvic acids. According to the free-ion activity model, only the free metal ion is available to biota. Nevertheless, DOM has been reported to decrease or increase metal uptake, leading to uncertainty concerning the bioavailability of metal-DOM complexes. In this work the effect of Aldrich humic acid on cadmium accumulation by the zebra mussel, Dreissena polymorpha, was studied under laboratory conditions. Mussels, collected in a drinking water reservoir, were exposed to varying environmentally relevant concentrations of cadmium in the presence and absence of humic acid. Cadmium concentrations in the mussel tissues were analyzed, and measurements with a cadmium-ion-selective electrode were made to determine the free cadmium ion activity in the exposure waters. The uptake of humic acid by the zebra mussels was measured by the decrease of the total organic carbon (TOC) concentration in the water over time. The free cadmium ion activity in the water decreased from 51.6% to 19.9% of the total cadmium concentration in the presence of humic acid. This decrease by a factor of 2.6 resulted in a decrease in the cadmium uptake rate in the soft tissue of zebra mussels from 12.9 to 7.9 nmol/g dry wt/day, which corresponds to a decrease by a factor of 1.6. This implies that cadmium uptake rates were higher than predicted by the free-ion activity model and indicates that cadmium-humic acid complexes are partly available to zebra mussels.
机译：水生系统中的金属形态主要取决于溶液中存在的配体的类型和浓度。一组非常重要的络合剂是溶解的有机物（DOM），例如腐殖酸和黄腐酸。根据自由离子活性模型，只有自由金属离子可用于生物群。然而，据报道DOM降低或增加了金属吸收，导致金属DOM复合物的生物利用度不确定。在这项工作中，在实验室条件下研究了斑马贻贝Dreissena polymorpha的Aldrich腐殖酸对镉积累的影响。在存在和不存在腐殖酸的情况下，将收集在饮用水水库中的贻贝暴露于与环境相关的各种浓度的镉。分析贻贝组织中的镉浓度，并用镉离子选择电极进行测量，以确定暴露水中的游离镉离子活性。斑马贻贝对腐殖酸的吸收是通过随时间推移水中总有机碳（TOC）浓度的降低来衡量的。在存在腐殖酸的情况下，水中的游离镉离子活性从总镉浓度的51.6％降至19.9％。这种降低了2.6倍的结果导致了斑马贻贝的软组织中镉的吸收率从12.9降低到7.9 nmol / g干wt /天，相当于降低了1.6倍。这意味着镉吸收率高于自由离子活性模型预测的值，并表明斑马贻贝可部分获得镉-腐殖酸复合物。

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