渭河流域关中段地表水重金属的污染特征与健康风险评价

Pollution Characteristics and Health Risk Assessment of Heavy Metals in Surface Water in Guanzhong Section of the Weihe River Basin

由于重金属的毒理性及其对水生生态系统的重要影响,水生环境的重金属污染已成为全世界关注的问题。渭河是黄河的第一大支流,近年来随着沿岸社会经济的发展,渭河的水质受到严重的威胁,但是对渭河流域地表水重金属的污染状况缺乏全面评估。以渭河流域关中段为研究区域,采集了该流域35个地表水样品,检测了12种重金属元素(Cr、Mn、Fe、Ni、Cu、Zn、As、Hg、Pb、Al、V和Ca),运用多元统计方法和健康风险评价模型研究了地表水中重金属的污染特征和健康风险。结果表明,地表水中12种金属元素的平均质量浓度大小顺序为:Ca>Fe>Cr>Al>Zn>V>Pb>Cu>As>Hg>Mn>Ni,其中Fe和Hg的质量浓度超过我国相应水质标准;采用反距离加权插值法(Inverse Distance Weighted)得出渭河流域地表水中重金属质量浓度的空间分布图,发现污染较为严重的主要地区为长安区和华州区。通过荷载分析得到4个主成分,Cr、Mn、Cu、As、Pb、Al和V为第1主成分,主要受到工业源和农业源的影响;Fe、Ni和Ca为第2主成分,主要受到地质环境和成土过程的影响;Hg和Zn分别为第3、4主成分,Hg主要受到城市生产生活的影响;Zn主要为地球化学来源。健康风险评价表明,饮用水途径引起的各种金属元素的年均健康风险均高于皮肤入渗途径,揭示饮用水是主要的暴露途径,致癌金属元素Cr和As引起的成人和儿童的年均健康风险数量级总体介于10^(−8)—10^(−6) a^(−1),非致癌金属元素Mn、Fe、Ni、Cu、Zn、Hg、Pb、Al和V引起的成人和儿童的年均健康风险数量级总体介于10^(−14)—10^(−9) a^(−1),发现致癌风险是影响成人和儿童的年均健康风险的主要因素,Cr是引起人群年均健康风险的主要因子,金属元素引起的年均健康风险值集中在10^(−13)—10^(−11) a^(−1),对流域的暴露人群没有形成明显的危害。该研究的结果可为该流域重金属的污染防治和保障城镇居民的用水安全提供科学依据。

Due to the toxicity of heavy metals and their significant impact on aquatic ecosystem,heavy metal pollution in the aquatic environment has become a worldwide issue.The Weihe River is the first major tributary of the Yellow River and its water quality has been seriously deteriorated in recent years during the socio-economic development of the basin.However,there is a lack of comprehensive assessment of heavy metal pollution in surface waters of the Weihe River Basin.In this study,35 surface water samples were collected from the Guanzhong section of the Weihe River Basin,and 12 heavy metal elements(Cr,Mn,Fe,Ni,Cu,Zn,As,Hg,Pb,Al,V and Ca)were analyzed.The pollution characteristics and health risks of heavy metals in surface waters were studied using multivariate statistical methods and health risk evaluation models.Results showed that the average concentration of 12 metals in the surface water followed this order:Ca>Fe>Cr>Al>Zn>V>Pb>Cu>As>Hg>Mn>Ni.Fe and Hg concentrations exceeded the corresponding water quality standard of China.Inverse Distance Weighted Interpolation was used to derive the spatial distribution of heavy metals in surface waters.It was found that the most serious polluted areas were Chang’an and Huazhou districts.Four principal components were obtained based on load analysis results.Cr,Mn,Cu,As,Pb,Al and V were included in the first principal component and were mainly influenced by industrial and agricultural sources.Fe,Ni and Ca appeared in the second principal component,mainly influenced by the geological environment and the soil formation process;Hg and Zn were in the third and fourth principal components,respectively.Hg was mainly influenced by urban production and living,while Zn was mainly from geochemical sources.A health risk evaluation showed that the annual average health risk of heavy metal from drinking water was higher than that via dermal exposure,indicating that drinking water was the main exposure route.The annual average health risk for adults and children due to carcinogenic elements(i.e.,Cr and As)ranged from 10^(−8)-10^(−6) a^(−1);and the risk due to non-carcinogenic elements(i.e.,Mn,Fe,Ni,Cu,Zn,Hg,Pb,Al,and V)ranged from 10^(−14) to 10^(−9) a^(−1).The carcinogenic risk was the main factor affecting the annual average health risk for adults and children.Cr was the main element that impacted the annual average health risk for the population.The annual average health risk values caused by metal elements were in the range of 10^(−13)–10^(−11) a^(−1).The results of this study provide a scientific basis for preventing and controlling heavy metal pollution in surface waters and improving water safety of the Weihe River Basin.