梵净山国家公园地表水重金属分布特征及生态风险评价

Distribution characteristics and ecological risk assessment of heavy metals in surface water of Fanjingshan National Park

运用美国环境保护署(US EPA)推荐的健康风险模型评价了梵净山国家公园14个地表水采样点水样中Cr、Mn、Cu、Zn、As、Se、Cd、Sb和Pb产生的健康风险。结果表明,除少数样品中Sb、Cr、Cu和Zn外,大多数样品溶解态重金属含量均符合相应的I类地表水水质标准与生活饮用水卫生标准。溶解态重金属存在多个来源,且主要受区域岩石地球化学背景、降雨和径流冲刷及地下水淋溶作用影响。其中,Cu、Cd、Zn、Pb主要来源于断层褶皱带内硫化物矿物,部分Cu可能来源于余家沟组辉绿岩;Se可能主要来源于回香坪组火山岩;Cr与Sb主要来源于梵净山群变质岩,部分Cr来源于超基性-基性岩;As来源于余家沟组辉绿岩及含砷矿物。健康风险评价结果显示,儿童受重金属污染的威胁相对更大,致癌物对人体健康危害的风险程度远远超过非致癌物,Cr经饮水途径产生的年均健康风险最大值高于国际放射防护委员会(ICRP)推荐的最大可接受风险水平(5.0×10^(-5)a^(-1)),Cr是梵净山国家公园内地表水体的主要致癌污染因子,非致癌重金属Mn、Cu、Zn、Pb、Se和Sb产生的年均健康风险,均远低于ICRP规定的最大可接受风险水平。

The health risk caused by heavy metals in water samples from 14 sampling points of Fanjingshan National Park were evaluated by the health risk assessment model from the US EPA.The results showed that concentrations of these heavy metals except that of Sb and Cr,Cu,Zn in a few samples were lower than the Drinking Water Quality Standard(GB 5749-2006)and the level I of the Surface Water Environment Quality Standard(GB 3838-2002).Results of multivariate analysis show that these heavy metals have been derived from several sources,which were mainly influenced by the geochemical background of rocks,rainfall erosion through runoff and leaching to groundwater.Cu,Cd,Zn and Pb were mainly derived from sulfides in the mineralized zone,and Cu may have been mixed with a diabase origin of the Yujiagou Formation;Se was mainly derived from the volcanic rocks of the Huixiangping Formation;Cr and Sb were mainly derived from the metamorphic rocks of the Fanjingshan Group,and Cr may have been mixed with an origin of the ultrabasic-basic rocks;As was mainly derived from diabase and arsenic-bearing minerals of the Yujiagou Formation.The results of the health risk assessment showed that children were more susceptible to the threat of heavy metal pollution than adults,and the health risks caused by carcinogenic heavy metals to human health through drinking water ingestion were higher than those of noncarcinogenic metals.The health risk caused by Cr was higher than the maximum allowance levels recommended by the International Commission on Radiological Protection(5.0×10^(-5)a^(-1)).The average annual risk caused by non-carcinogenic heavy metals(i.e.,Mn,Cu,Zn,Pb,Se,and Sb),which were far below the maximum allowance levels recommended by the ICRP.