黄河上游重金属元素分布特征及生态风险评价

选取黄河沿至三湖河口14个采样断面, 分析溶解态、悬浮态和沉积态As, Zn, Cu, Cr, Pb和Cd的分布特征及影响因素, 并评估其生态风险。黄河上游溶解态金属含量为ND(not detected)~5.496 μg/L (I类水), 悬浮态重金属含量为ND~1097.995 μg/g, 沉积态重金属含量为ND~75.524 μg/g。非度量多维尺度分析(NMDS)结果表明, 黄河上游溶解态重金属空间差异性显著, 悬浮态和沉积态重金属季节差异性显著。相关性分析结果表明, 黄河上游沉积物中Zn, Cu, Cr和Pb主要来源于自然作用, As和Cd存在一定程度的人为污染。水库的建立运行也影响黄河上游重金属分布趋势, 主要与大坝对悬浮物的截留作用、蓄水的稀释作用以及重金属在泥–水表面的分配作用有关。潜在生态风险指数评估结果表明, 黄河上游重金属生态风险整体上偏低, Cd和As贡献较大。

Distribution of Heavy Metals in the Upstream of Yellow River and Ecological Risk Assessment

14 sampling sections in the upstream of Yellow River were selected to detect concentrations of As, Zn, Cu, Cr, Pb and Cd, followed by ecological risk assessment. The metal content in water ranged among ND to 5.496 μg/L, while ND to 1097.995 μg/g in suspended solids (SS) and ND to 75.524 μg/g in sediment. NMDS results proved that metal contents in water displayed significant difference in spatial scale, while that in SS and sediments were remarkably diverse in different season. Correlation analysis proved that Zn, Cu, Cr and Pb were mainly from natural process, while As and Cd were partially from man-made pollution. Meanwhile, establishment and operation of reservoirs also impacted metal distributions, which could be the combined actions of interception to SS by big dams, dilution by impounding, and distribution effect in mud-water interface. Results by potential ecological risk index proved that heavy metals in the upstream of Yellow River showed low risk, and Cd and As played the important role.