长寿湖水库沉积物中重金属来源及生态风险评价

水库作为生活饮用水水源地,受人类活动影响较大,且污染物种类多、来源广、危害大。目前,关于水库沉积物中重金属污染状况分析的研究较少。以三峡库区长寿湖水库沉积物为研究对象,利用地累积指数(I_(geo))和潜在生态风险指数法,结合沉积年代学序列,对沉积物中重金属Co,Cd,Cr,Cu,Ni,Pb和Zn的垂直变化特征、重金属来源及生态风险评价进行了分析。地累积指数分析表明:表层沉积物中重金属累积顺序为CdCoZnNiPbCuCr,其中Cd和Zn累积较明显,属于轻度污染。潜在生态风险系数评价结果表明:沉积物中重金属潜在生态风险指数RI值大多数低于150,说明潜在生态风险整体较轻,但自1889年以来,RI值一直大于150,应当引起重视。应用主成分析法分析长寿湖水库沉积物中重金属来源,结果表明:水库沉积物中重金属主要来源于流域土壤的自然风化和土壤侵蚀,同时也受到龙溪河流域城市化、工业化发展导致的工业废水和生活污水排放的影响。

Sources analysis and ecological risk evaluation on heavy metals in Changshouhu Reservoir sediments

Geochronology, geo-accumulation index (Igeo), Hakanson Potential Ecological Risk Index (RI) and Principal Component Analysis (PCA) method were used to analyze vertical variation characteristics, sources, potential ecological risk of Co, Cr, Cu, Ni, Pb and Zn of Changshouhu Reservoir sediments in the Three Gorges Reservoir area. The Igeo results showed that the pollution extent of heavy metals in sediments from high to low were Cd, Co, Zn, Ni, Pb, Cu, Cr. Cd and Zn accumulated severely, showing a mildly contamination. The potential ecological risk evaluation results showed that RI values of the most of heavy metals in sediments were below 150, indicating that the overall potential ecological risk was light. But the RI value had been greater than 150 since 1989, which should be paid more attention to. The sources analysis results showed that the heavy metals were mainly derived from self-weathered soil and soil erosion, and also affected by industrial waste water and domestic sewage discharge caused by urbanization and industrial development in Longxi River basin.