西北高寒牧区水质评价与重金属健康风险评估

Water Quality Assessment and Heavy Metal Health Risk Evaluation in Northwest Alpine Pastoral Area

针对西北高寒牧区水质状况及其对人体健康的影响,采用主成分分析法对牧区水质指标进行评价,采用健康风险评价模型对水质中的重金属Cd、As、Cu、Pb、Fe进行健康风险评估。结果表明,氨氮、有机物、耐热大肠杆菌、总磷、总氮之间具有很强的相关性,有机物、氨氮及耐热大肠杆菌是影响牧区水质的主要污染物;Cd、As、Cu、Pb、Fe的浓度均达到了《地表水环境质量标准》(GB 3838—2002)Ⅲ类水标准,致癌重金属健康风险数量级远超非致癌重金属健康风险数量级,其风险水平平均相差105~107倍,但致癌重金属健康风险水平尚未超过国际辐射防护委员会(ICRP)推荐的最大可接受风险水平5.0×10^(-5)a^(-1),仍属于人体可接受风险。说明牧区水质中重金属对人体的危害较小。致癌重金属健康风险程度由高到低的顺序为Cd、As,非致癌重金属健康风险程度的顺序为Cu>Fe>Pb。

According to the water quality situation and its influence on human health in northwest alpine pastoral area,the water quality indicators of pastoral area were evaluated by using principal component analysis method.The health risk of heavy metal such Cd,As,Cu,Pb and Fe in water was evaluated by using the health risk assessment model.There was a strong correlation among ammonia nitrogen,organic matter,heat‑resistant E.coli,total phosphorus and total nitrogen.Organic matter,ammonia nitrogen and heat‑resistant E.coli were the main pollutants affecting water quality in pastoral area.The concentrations of Cd,As,Cu,Pb,and Fe all metⅢlevel criteria specified in Environmental Quality Standards for Surface Water(GB 3838-2002).The health risk of carcinogenic heavy metals was much higher than that of non‑carcinogenic heavy metals,and the risk levels varied by an average of 105-107 times.However,the health risk level of carcinogenic heavy metals did not exceed the maximum acceptable risk level of 5.0×10^(-5)a^(-1)recommended by the international commission on radiological protection(ICRP),which was an acceptable risk for human body.The results indicated that the heavy metals in water in pastoral area were less harmful to human health.The health risk of carcinogenic heavy metals in descending order was Cd and As,while that of non‑carcinogenic heavy metals in descending order was Cu,Fe and Pb.