苏州城市土壤重金属污染特征及风险评价

Characteristic and Risk Assessment of Heavy Metals Contamination of Soil in Suzhou City

为考察苏州主城区土壤的重金属污染状况,从城区68个主要居民集聚点,分别在公路边、居民区和公园获得了167份土样,并分析了铬、镉、砷、铅、汞的浓度,在分析其重金属污染特征和评估其健康风险的过程中,引入了GIS地理空间系统分析和基于蒙特卡洛随机模拟系统的不确定性分析。结果表明,苏州主城区土壤重金属污染分析结果发现As、Pb和Hg含量较高,超出江苏省土壤背景值,Cr和Cd含量相对偏低。重金属含量在不同行政区之间存在一定差异,重金属污染严重的土壤大体呈点状分布。公路两侧土壤的As、Pb和Hg污染较为严重。相关性分析和PCA分析结果表明Pb和As、Cd污染可能有相同的来源。重金属健康风险评价结果显示儿童非致癌风险和致癌风险都高于成人;成人和儿童的风险值分布非常一致,各行政区非致癌风险和致癌风险值差异不大,总体都处于可接受范围。蒙特卡洛随机模拟处理后重金属的风险值稍低于未经处理的直接数据计算的结果,仍处于安全范围;经口暴露的重金属是影响重金属健康风险的重要因素,儿童体重的大幅度变化会强烈影响土壤重金属对儿童的健康风险。

167 soil samples were obtained at 68 sampling points from the major residential quarters and the concentrations of chromium, cadmium, arsenic, lead and mercury were analyzed. Analysis results of metals in Suzhou soil showed that As, Pb and Hg content is much higher than soil background values of Jiangsu Province, while Cr and Cd content is relatively low. HMs concentrations varied between districts and sampling sites of high HMs concentration showed punctate distribution. As, Pb and Hg pollution in the soil on both sides of the road is relatively serious. The correlation anal-ysis and PCA analysis results show that Pb, As and Cd may come from the same source. The non-carcinogenic risks and carcinogenic risks of heavy metals in soil are higher for children than adults. The spatial distributions of HI and TCR for adults were similar to those for children, most of which indicated acceptable risk without significant difference. Uncertainty analysis shows that simulated probabilities were lower than those obtained from models using deterministic param-eters. For adults, for both HI and TCR, the ingestion rate contributed >60% to the sensitivity of the parameter. While the bodyweight is the most sensitive parameter for children’s health risk.