成都平原表层水稻土重金属污染健康风险分析

Concentration and health risk of heavy metals in topsoil of paddy field of Chengdu Plain

采样分析了成都平原表层水稻土(0—20 cm)中As、Cd、Cr、Hg、Pb、Cu、Zn含量,参照国家土壤环境质量标准和土壤背景值,并利用健康风险评价模型对土壤重金属环境质量状况和人体健康风险进行了评价.结果表明,成都平原水稻土表层7种重金属平均含量分别为As:9.69 mg·kg-1、Cd:0.12 mg·kg-1、Cr:79.5 mg·kg-1、Hg:0.04 mg·kg-1、Pb:47.5 mg·kg-1、Cu:29.3 mg·kg-1、Zn:81.7 mg·kg-1.与成都地区土壤背景值相比,As、Cr、Pb、Cu、Zn在表层水稻土中有明显积累,部分样区土壤重金属超过《土壤环境质量标准》(GB15618—1995)标准值的二级标准,存在外源污染输入,但污染程度较轻.人体健康风险分析结果表明,经土壤-口接触行为摄入是该区域人体重金属暴露风险的主要途径,重金属致癌风险As>Cd,非致癌总风险Cr>Cu>Hg>Pb>Zn,无论儿童还是成人,重金属致癌风险值和非致癌风险值均低于风险阈值,风险值均在可接受水平内,但儿童健康风险值高于成人,应加强监管.

In order to evaluate clearly soil environment status, the accumulation and distributions of heavy metal elements, arsenic, cadmium, chromium, mercury, lead, copper, and zinc in paddy soil （0--20 cm）of Chengdu plain, Sichuan Province were researched. The pollution index was employed to evaluate the quality of the soil compared with the National Soil Quality Standard-Grade Ⅱ. The health risks of the above-mentioned heavy metals to adults and children by direct ingestion, inhalation of suspended particles, and dermal absorption were assessed using USEPA health risk assessment mode. The results indicated that, the mean contents of heavy metals in topsoil （ depth of 0-20 era） were 9.69 mg. kg - 1 （ As）, 0.12 mg. kg - 1（ Cd）, 79.5 mg.kg - 1 （ Cr）, 0.04 mg. kg - 1 （Hg）, 47.5 mg.kg -1 （ Pb）, .29.3 mg. kg -1 （ Cu）, 81.7mg. kg-1 （Zn）, respectively. Because of the influences from human activities, As, Cr, Pb, Cu and Zn had high accumulation in soils by comparison to the background concentrations of soil elements in Chengdu area soil. Heavy metal maximum content （except Pb） in sampling sites had exceeded the second grade standard values of Chinese environmental quality standards for soils （GB 15618--1995 ）. There were external pollution input, but the paddy soils were just slightly contaminated by heavy metals. Human health risk analysis results show that the main way for human exposure risk of heavy metals was direct ingestion and inhalation of suspended particles. The order of individual risk index for the health of childrenand adult was As 〉 Cd （ carcinogenic risk）, and Cr 〉 Cu 〉 Hg 〉 Pb 〉 Zn （ non-carcinogenic risk）. The carcinogenic risk and the non-carcinogenic risk values of heavy metal are less than risk threshold volue, all the risk values are within the acceptable level. However, children were more sensitively affected by heavy metals from irrigated land. Attention should be paid to children＇s health monitoring in such areas.