三峡水库蓄水初期鲤鱼重金属富集特征及健康风险评价

于2011-2012年在三峡库区干流水域及7条典型支流中采集鲤鱼样品,通过测定鱼体肌肉组织中Cr、Cd、As、Pb、Ni、Cu和Zn等7种重金属含量,分析了三峡库区蓄水后的鱼体重金属污染水平、各金属元素之间的相关性及在库区各水域的分布特征,并利用目标危险系数(THQ)对库区居民通过食用鱼类摄入重金属的健康风险进行了评价.结果显示,所有鱼类样品中均检测出这7种重金属,但含量低于国家规定的卫生健康标准.不同重金属在鱼体肌肉中差异明显,Zn的平均含量最高(5.88 mg·kg-1),Cd平均含量最低(0.013 mg·kg-1).所有7种重金属可分为4类,式中,Cr和Cu,Pb和As相关系数较大.与库区外其他水域相比,三峡水库中鱼体重金属含量处于较低水平,且在蓄水后未发生显著变化.受到水位升高和悬浮物沉降的影响,库区内干流鱼体中大部分重金属含量变化趋势为从库尾的洛碛向库中的巫山递减.THQ法评价结果认为,食用库区鱼类健康风险较低.

Pollution characteristics and health risk assessment of heavy metals in carp (Cyprinus carpio) from the Three Gorges Reservoir after 175 m impoundment

The concentrations and distribution characteristics of heavy metals in carp (Cyprinus carpio) collected from three main stem sections and seven typical tributaries of Three-Gorge Reservoir (TGR) were investigated after the 175 m impoundment. The concentrations of Cr, Cd, As, Pb, Ni, Cu and Zn in all samples were measured, and the Target Hazard Quotient (THQ) was used to assess the potential health risk to the local consumers. The results showed that Zn concentration was the highest (5.88 mg·kg^-1 in average) in fish muscle, while Cd concentration was the lowest (0.013 mg·kg^-1 in average). All heavy metal concentrations in carps were lower than the tolerance limits in the related standards. Pearson correlation matrix as well as cluster analyses were applied to identify inter-relationships of the heavy metals. Cluster analysis identified four clusters among the studied heavy metals based on their concentrations in fish samples. Significant positive correlation was found between Cr and Cu and between Pb and As. A significant positive correlation was also observed between Pb concentrations and fish sizes, indicating a bioaccumulation potential of Pb in fish. Comparing to fishes in other areas of Yangtze River Basin, the concentrations of heavy metals in carp from TGR were low, and there was no obvious increasing tendency after impoundment. Moreover, due to the enhanced sediment deposition along the reservoir flow, a decreasing trend of these heavy metals in carp was observed from upstream to downstream in the main stream of TGR. Based on the THQ analysis, we concluded that the seven heavy metals in fish tissue posed no obvious health risk to the general population consumption.