基于健康风险的土壤修复目标研究程序与方法——以多环芳烃污染土壤再利用工程为例
Procedures and Methodology for Studying Soil Remediation Objectives Based on the Human Risk Assessment—A Case Study of Reuse of PAH-Contaminated Soil in Shanghai
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摘要: 提出了基于人体健康风险的土壤修复目标的制定方法和程序,并以上海市某重大工程多环芳烃污染土壤处理后再利用工程为例,模拟了多环芳烃在处置场地上的多介质迁移途径及人体暴露场景。模拟结果显示,填埋场污染土壤苯并(a)芘(该污染物毒性因子高,毒性强,致癌风险相对较大)经口摄入和皮肤接触途径最大致癌暴露量分别为1.89×10-6和0.93×10-6mg·kg-1·d-1,人体最大致癌风险水平分别为1.38×10-5和6.79×10-6,超出了中国规定的单致癌污染物的可接受风险水平(≤10-6)。苯并(a)芘呼吸吸入途径最大致癌暴露量为7.79×10-10mg.m-3,人体最大致癌风险水平为6.86×10-10。基于场地的特征条件和参数,以保护人体健康为目的,确定了再利用作为填埋场中层覆土的土壤中5种多环芳烃污染物的修复目标限值(w,mg·kg-1)分别为:苯并(a)芘,0.994;二苯并(a,h)蒽,0.995;苯并(a)蒽,9.95;苯并(b)荧蒽,9.95;苯并(k)荧蒽,99.5。Abstract: Methodology and procedures for studying soil remediation goals are introduced,based on human health risk assessment.Properties of PAH-contaminated soil and exposure scenario in the landfill site are analyzed and simulated.Results show that the maximum exposure intake(MEIs) benzo(a)pyrene by oral ingestion and dermal contact is 1.89×10-6 and 0.93×10-6 mg·kg-1·d-1,respectively.The maximum carcinogenic risk(MCRs) of the two exposure pathways is at 1.38×10-5 and 6.79×10-6,separately,both of which exceed the acceptable carcinogenic risk level of 10-6.This level is the benchmark regulated for assessing the human health impact from the individual carcinogenic contaminant in China.The MEI of benzo(a)pyrene by inhalation is 7.79×10-10 mg·m-3 and its MCR is 6.86×10-10.Taking into account site-specific geo-condition and parameters,the remediation targets(w,mg·kg-1)of 5 PAHs,including benzo(a)pyrene,dibenzo(a,h)anthracene,benzo(a)anthracene,benzo(b)fluoranthene and benzo(k)fluoranthene,for reuse of the mid-layer of overlying soil in landfill sites are set at 0.994,0.995,9.95,9.95 and 99.5,respectively.