云贵高原小黄泥河流域重金属分布特征及健康风险评价

Distribution and health risk assessment of heavy metals in Xiaohuangni River Basin on Yunnan-Guizhou Plateau

小黄泥河为珠江源区南盘江流域主要支流之一,也是云贵高原重要的江河水功能区,查明小黄泥河流域地表水重金属分布特征、污染程度和健康风险,可以为珠江源区的生态环境保护提供有力支撑.系统采集小黄泥河干流及支流河水样品,对河水样品中重金属Fe、Mn、Cu、Pb、Zn、Cd和类金属As进行测定,并采用内梅罗综合污染指数法和健康风险评价模型,对小黄泥河流域地表水中的重金属进行污染评价和健康风险评价.结果表明,小黄泥河流域河水中重金属平均浓度顺序为:Fe(810.66μg·L^(−1))>Mn(126.90μg·L^(−1))>Zn(24.71μg·L^(−1))>As(2.45μg·L^(−1))>Cu(2.33μg·L^(−1))>Pb(0.43μg·L^(−1))>Cd(0.03μg·L^(−1)),其中Fe和Mn两种重金属存在超标现象,其他重金属均未出现超标现象.相关性分析及因子分析表明,地表水中7种重金属元素主要受到采煤活动、道路交通和地质背景3个因素的控制,其贡献率分别为48.00%、19.66%和15.97%.Fe和Mn的单因子污染指数较高,存在不同程度的污染,而其他重金属总体上不存在污染风险.综合污染指数评价结果显示,干流水质总体优于支流,下游支流为高度污染,上游支流为轻度污染,均主要受到Fe和Mn的影响.地表水中重金属产生的健康风险总体可控,其大小依次为As>Cd>Fe>Cu>Pb>Zn>Mn,除下游支流部分点位As的健康风险高于最大可接受风险值外,致癌物Cd及非致癌物Cu、Pb、Fe、Mn和Zn的健康风险均远低于最大可接受风险值.

The Xiaohuangni River is one of the main tributaries of the Nanpan River Basin in the source area of the Pearl River,and it is also an important river water function area in the Yunnan-Guizhou Plateau.The identification of the distribution characteristics,pollution levels and health risks of heavy metals in the surface water of the Xiaohuangni River basin can provide strong support for the protection of the source area of the Pearl River.The samples of main stream and tributaries of Xiaohuangni River were collected to determine the concentrations of Fe,Mn,Cu,Pb,Zn,Cd and metalloid of As in the water.The Nemerow index method and health risk assessment model were applied to assess the degree of contamination and health risk of heavy metals in surface water.The results show that the average concentration of each heavy metals can be ranked as Fe(810.66μg·L^(−1))>Mn(126.90μg·L^(−1))>Zn(24.71μg·L^(−1))>As(2.45μg·L^(−1))>Cu(2.33μg·L^(−1))>Pb(0.43μg·L^(−1))>Cd(0.03μg·L^(−1)),in which Fe and Mn are the main excessive heavy metals,and other heavy metals do not exceed the standard.Correlation analysis and factor analysis show that the seven heavy metals are mainly affected by coal mining activities,traffic sources and geological background,and their contribution rates are 48.00%,19.66%and 15.97%,respectively.According to single factor pollution index,Fe and Mn have different degrees of pollution,while other heavy metals generally are pollution-free.And according to the comprehensive pollution index,the water quality of the main stream is better than that of the tributaries,the downstream tributaries are highly polluted and the upstream tributaries are slightly polluted,both are mainly affected by Fe and Mn.The health risk caused by heavy metals in the surface water is generally controllable,and the health risk value of each heavy metals can be ranked as As>Cd>Fe>Cu>Pb>Zn>Mn.Except that the health risk of As at some points of downstream tributaries is higher than the maximum acceptable risk value,the health risk of carcinogen Cd and non-carcinogens Cu,Pb,Fe,Mn and Zn are far lower than the maximum acceptable risk value.