官厅水库主要入库河流(洋河)表层沉积物重金属污染特征及风险水平

洋河是官厅水库重要的入库河流,而水体沉积物污染将直接影响水库水质安全.因此,采集了洋河水系表层沉积物,研究了6种重金属的污染特征及风险水平.结果表明,洋河水系表层沉积物中Cd、Cr、Cu、Ni、Pb和Zn的含量均值分别为0.34、59.91、30.64、30.85、39.51和129.27mg·kg~(-1).源解析表明,Cd、Pb和Zn主要来源于人为活动(富集系数EF1.5),Cr、Cu和Ni主要来源于自然过程.洋河水系表层沉积物单元素潜在生态风险顺序为CdPbCuNiCrZn,其中,Cd表现为强生态风险,特别是在支流清水河段呈现极强生态风险,其他5种重金属在流域尺度上表现为生态风险较小;6种重金属综合潜在生态危害指数均值为143.70,处于轻微风险等级.洋河水系表层沉积物中重金属无生物毒性或生物毒性发生率较低,但清水河段和干流中游段生物毒性发生率相对较高.

Pollution and ecological risk of heavy metals in surface sediments from input river (Yang River) of Guanting Reservoir

Yang River is one of the most important input rivers of Guanting Reservoir. Sediment contamination in Yang River can directly affect the water quality of Guanting Reservoir. Pollution characteristics and ecological risk of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) in surface sediments from Yang River system were investigated. The results show that the average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were 0.34, 59.91, 30.64, 30.85, 39.51 and 129.27 mg·kg^-1, respectively. The source identification indicates that Cd, Pb, and Zn were mainly originated from the anthropogenic activities, while Cr, Cu and Ni were originated from the natural processes. The single-element potential ecological risk of heavy metals in Yang River followed the order of:Cd> Pb> Cu> Ni> Cr> Zn. Among the studied metals, the potential ecological risk of Cd belonged to strong environmental risk, especially in Qingshui River, which is the tributary of Yang River, the ecological risk was extremely high, while Pb, Cu, Ni, Cr, and Zn posed slight ecological risk at catchment scale. The results of the integrated potential ecological risk index revealed that heavy metals in the surface sediments of Yang River had slight ecological risk with the average index of 143.70. The heavy metals in surface sediment from Yang River system had no or lower rate of bio-toxicity occurrence, while in Qingshui River and middle reaches of Yang River, the occurrence rate of bio-toxicity was relatively high.