浙江省农田土壤多环芳烃污染及风险评价

Contamination and risk assessment of polycyclic aromatic hydrocarbons in farmland soils of Zhejiang Province,China

为探究浙江省农田土壤中16种优控多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)含量、来源及生态和健康风险,用网格布点法采集了62个农田土壤样品并进行实验分析。结果表明,ΣPAHs浓度范围为34.04~1990.38ng·g^-1,污染物以高环类PAHs为主,研究区域内所有土样苯并[a]芘(BaP)浓度均未超过我国新颁布的《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618—2018)中的风险筛选值。采用比值法及主成分分析研究其环境来源,结果显示主要来自于交通污染、煤炭和薪柴燃烧。内梅罗综合污染指数法评价结果表明,研究区有87.10%的样点存在生态风险。毒性当量因子风险评价法分析结果显示,PAHs的毒性当量浓度范围为1.53~268.27 ng·g^-1,7种致癌PAHs为污染主体,平均占比高达99.18%。暴露量估算结果显示,经口摄入是PAHs致癌风险最高的暴露途径。健康风险评价显示,土壤中PAHs暴露暂时不会对人群产生明显的非致癌风险,但儿童的综合致癌风险已超过可接受范围,需引起重视。

In this study,gridded field observations at 62 sites were undertaken to determine the concentration,composition,sources,and ecological and health risks of 16 polycyclic aromatic hydrocarbons(PAHs)in Zhejiang Province.The methods consisted of Soxhlet extraction and silica gel column chromatography,followed by gas chromatography-mass spectrometry(GC-MS).The concentrations of SPAHs ranged from 34.04 ng·g^-1 to 1 990.38 ng·g^-1,and high molecular weight PAHs were dominant in all soils.The level of benzo[a]pyrene(BaP)was lower than the National Soil Environmental Quality Standard(GB15618-2018).Source diagnostic ratio and principal component analysis showed that vehicle emissions,and coal and biomass combustion,were the main sources ol PAHs.According to Nemerow's pollution index,ecological risks extensively exist in 87.10%of the sampling sites.Toxic equivalents of PAHs ranged from 1.53 ng·g^-1 to 268.27 ng·g^-1,in which 7 carcinogenic PAHs contributed 99.18%.PAHs exposures of adults and children via ingestion,dermal absorption,and inhalation were estimated.I Ingestion was found to be the most important PAHs exposure pathway,and non-carcinogenic risks were negligible,while the comprehensive carcinogenic risk for children exceeded acceptable levels.This research provides useful information on human exposure to PAHs in farmland soils of Zhejiang Province,and is valuable for policy makers and scientists.