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首页> 外文期刊>Journal of soil & sediments >Variations in concentrations and bioavailability of heavy metals in rivers during sediment suspension-deposition event induced by dams: insights from sediment regulation of the Xiaolangdi Reservoir in the Yellow River
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Variations in concentrations and bioavailability of heavy metals in rivers during sediment suspension-deposition event induced by dams: insights from sediment regulation of the Xiaolangdi Reservoir in the Yellow River

机译：大坝引起的泥沙悬浮沉积过程中河流中重金属的浓度和生物利用度变化：黄河小浪底水库泥沙调节的启示

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PurposeThe variations of concentrations, speciation, and bioavailability of heavy metals during large-scale sediment suspension-deposition events caused by dams in rivers are not well understood.Materials and methodsIn this study, the sediment regulation of the Xiaolangdi Reservoir of the Yellow River was chosen as a case to study the effects of large-scale sediment suspension-deposition events on the concentrations, speciation, and bioavailability of As, Cr, Cu, Ni, Pb, and Zn in river water, and the bioaccumulation and biotoxicity of heavy metals in river water samples to Daphnia magna were examined. The water in the reservoir was also collected to determine the suspended sediment (SPS) concentration and conduct bioaccumulation and biotoxicity experiments.Results and discussionDuring sediment regulation, the SPS concentration in river water increased from 0.02gL(-1) in the reservoir to 54.8gL(-1) at the dam outlet, and then it decreased along the downstream river due to SPS deposition. The heavy metal concentrations in SPS at the dam outlet were higher than those in the reservoir sediment and remained stable at downstream sites. No spatial trends were found in their exchangeable fraction. Correspondingly, the dissolved concentrations at the dam outlet were lower than those in the reservoir. The body burdens in Daphnia magna for the reservoir water samples were higher than those for the dam outlet. However, higher lethality of Daphnia magna at the dam outlet was found due to other contaminant release caused by sediment resuspension.ConclusionsThe results revealed that the resuspended sediment which has smaller particle sizes and more sorption sites in the reservoir was a sink for heavy metals; the downstream SPS deposition process has no considerable influence on the heavy metal distribution. This study suggests that sediment regulation is conducive to delivering the reservoir sediment to the sea and reducing the eco-environmental risks of heavy metals in the downstream of the Xiaolangdi Reservoir. However, it might increase the total eco-environmental risks of pollutants.
机译：目的尚不清楚河流大坝引起的大规模泥沙悬浮沉积过程中重金属的浓度，形态和生物利用度的变化。材料与方法本研究选择黄河小浪底水库的泥沙调节以研究大型沉积物悬浮沉积事件对河水中砷，铬，铜，镍，铅和锌的浓度，形态和生物利用度以及重金属的生物累积和生物毒性的影响为例检查了大水蚤的河水样品。结果和讨论在沉积物调节过程中，河水中的SPS浓度从水库中的0.02gL（-1）增加到54.8gL，并进行了生物富集和生物毒性实验。 （-1）在大坝出口处，然后由于SPS沉积而沿下游河减少。大坝出口处SPS中的重金属浓度高于水库沉积物中的重金属浓度，并在下游位置保持稳定。在其可交换部分中未发现空间趋势。相应地，大坝出口处的溶解浓度低于水库中的溶解浓度。大型蚤（Daphnia magna）的水库水样的身体负担高于大坝出水口的身体负担。然而，由于沉积物的再悬浮会导致其他污染物的释放，因此在大坝出口处发现了大型蚤（Daphnia magna）的致死性。结论研究结果表明，重悬浮的沉积物具有较小的粒径和更多的吸附位，是重金属的汇。下游的SPS沉积工艺对重金属的分布影响不大。这项研究表明，泥沙调节有利于将储层泥沙排入海中，并减少小浪底水库下游重金属的生态环境风险。但是，这可能会增加污染物的总体生态环境风险。

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