小江回水区水体重金属污染状况调查与评价

Investigation and evaluation of water heavy metals pollution in the backwater area of Xiaojiang River in the Three Gorges reservoir area

2010年三峡大坝首次成功蓄水到175m,在小江形成一个长约60km的回水区域即小江回水区.为了探析三峡大坝蓄水对库区水环境的影响,通过野外采样和室内测定,分析了三峡库区支流小江回水区河水中Fe、Mn、Cr、Pb、Cu和Cd的含量与空间分布,并运用单因子指数法和内梅罗指数法对其污染状况进行了评价.结果发现研究水体Pb含量达国家地表水环境质量Ⅱ级标准的2～3倍,其余重金属含量则均在Ⅱ级标准以内;水中重金属空间分布存在明显异质性;两种指数法评价均发现研究水体存在严重Pb污染.因此,应密切关注小江回水区的Pb含量变动情况.

To explore the impoundment influence on the water environment of the Three Gorges Reservoir( TGR),this paper used field sampling and laboratory examination methods to analyze the water of the backwater area of Xiaojiang River. Six metals involving Fe,Mn,Cr,Pb,Cu and Cd were detected,and then spatial distribution of these elements and their pollution severity were evaluated by Single Factor Index( SFI) and Nemerow Index( NI) methods. The results show that water Pb concentration is 2-3 times higher than the limit II of National Environmental Quality Standards for Surface Water of China( GB3838- 2002),while the other elements are below the limit II.Spatial distribution of heavy metals in water has significant heterogeneity. Both SFI and NI show a severe pollution by Pb in the water body. Therefore,attention should be paid to the severe Pb pollution in the backwater area of Xiaojiang River.