废弃工业场地有机氯农药分布及生态风险评价

Organochlorine pesticides distribution and ecological risk assessment in a abandoned industrial site

对典型废弃有机氯农药生产场地中土壤中六六六(α-,β-,γ-,δ-HCH)和滴滴涕(p,p’-DDT,p,p′-DDE,p,p′-DDD,o,p’-DDT)的残留特征进行了分析。结果发现场地中六六六的残留水平为13.16～148.71mg/kg;滴滴涕残留水平为3.02～67.42mg/kg。表层土残留最大,随着土层加深,污染物残留逐渐下降。六六六的残留水平要高于滴滴涕。残留分析表明场地中有机氯农药有逐步降解的趋势,但是现有残留水平超出了国家的土壤质量二级标准。根据场地土地利用方向,运用CalTOX暴露模型结合Monte Carlo分析进行了健康风险评价,结果表明,健康风险主要来自于两种人体暴露途径:皮肤吸收和呼吸摄入,总的风险都超过了可接受风险水平(10-6),通过敏感性分析表明5个参数对于总的风险贡献较大。该研究对于有机氯农药场地土壤的风险管理提供了依据。

China has abandoned organochlorine pesticides （HCHs and DDTs） production and usage for more than 20 years. A field survey was conducted in a contaminated industrial site in southern Beijing, China. Concentrations and distribution of the organochlorine pesticides （α-, β-, γ-, δ-HCH, p,p＇-DDT, p,p＇-DDE, p,p＇-DDD and o,p＇-DDT） in profiles of soil were investigated. Results showed that mean concentrations of total hexaehloroeyclohexane isomers （HCHs） and total dichlorodiphenyltrichloroethane isomers （DDTs） in soils ranged from 13. 19 to 148.71 mg/kg, and from 3.02 to 67.42 mg/kg, respectively. Organochlorine pesticides （OCPs） concentration peaked at the surface and declined in soil profile with depth and the amounts of HCHs in three profiles of soil were larger than DDTs. Composition analysis indicated that there was a trend of degradation of OCPs in the site, but the mean of HCHs and DDTs concentration were over the state warning standard limit （HCHs ：0.50 mg/kg; DDTs ：0.50 mg/kg）. According to current land use development, health risk assessment with CalTOX and Monte Carlo analysis showed that health risks mainly came from two exposure pathways： dermal uptake and inhalation, and that the total risk values all exceeded the general acceptable health risk value（ 10^-6）. The sensitivity analysis indicated that five parameters significantly contributed to total risk. The results will be available for risk management in OCPs contaminated industrial site.