大气PM_(2.5)和PM_(10)中重金属形态分布特征及环境风险评估

Speciation distribution and environmental risk of heavy metals in PM_(10) and PM_(2.5)

目的探讨重金属在不同粒径大气颗粒物中的赋存形态和生物有效性,并评估其环境风险。方法采用BCR连续提取法结合电感耦合等离子体质谱法(ICP-MS)测定上海某高校室外采集的PM_(10)和PM_(2.5)中10种重金属(Cr、Mn、Ni、Cu、Zn、Cd、Sb、Ba、Hg、Pb)不同形态的含量,并通过富集因子法(EF)和风险评估指数法(RAC)分析重金属的来源及环境风险。结果 Pb和Cd在PM_(2.5)中的残渣态含量高于在PM_(10)中含量,Cr和Ni在PM_(2.5)中的残渣态含量低于在PM_(10)中含量。富集因子法结果显示,Cd、Sb、Zn、Pb的人为污染较明显。风险评估指数法显示,Cr和Ni存在潜在环境风险,Pb和Mn对环境为高风险,而Cd有极高的环境风险。结论不同粒径的颗粒物对不同重金属的赋存形态及富集情况有不同程度的影响;大气颗粒物中重金属浓度、形态分布和生物有效性对评估其环境风险具有重要意义。

Objective To evaluate the environmental risk of heavy metals in atmospheric particulate matter through analyzing the chemical speciation and bioavailability. Methods Heavy metals in PM10 and PM2.5 samples,collected in a campus in Shanghai,were extracted in different fractions through BCR sequential extraction procedure respectively. Heavy metals（Cr,Mn,Ni,Cu,Zn,Cd,Sb,Ba,Hg and Pb） in PM10 and PM2.5 were determined by ICP-MS,the source and environmental risk of which were analyze based on enrichment factor（EF） and risk assessment code（RAC）. Results Compared with PM10,the proportions of residual Pb and Cd were much higher in PM2.5,whereas Cr and Ni were lower in PM2.5.EF indicated anthropogenic factor generated obvious Cd,Sb,Zn and Pb pollution. RAC implied Cr and Ni had potential environmental risk,Pb and Mn higher risk,Cd extremely higher risk. Conclusion Various heavy metals present different speciation and enrichment in PM10 and PM2.5,their concentrations,speciation distribution and bioavailability are important indexes for the environmental risk evaluation.