贵阳市冬季PM_(2.5)中典型重金属元素的化学形态分析与健康风险评价

为了更准确地研究重金属的生物有效性和对环境与人体的潜在生态危害,采用改进BCR法分析了贵阳市冬季PM_(2.5)中Cu、Mn、Co、Cd、Pb这5种重金属元素的化学形态,并评价了它们的生物有效性和健康风险。结果表明:不同重金属元素形态分布存在差异,Cu主要是弱酸溶态,其次是可氧化态;Mn主要是弱酸溶态,其次是残渣态;Co没有检测出可还原态,而在其他3种形态分布比较平均;Pb和Cd绝大部分都是弱酸溶态。生物有效性系数(K)分析结果表明:重金属生物有效性强弱顺序为CdPbMnCuCo,其中Cd和Pb的K0.8,属于生物可利用性元素;Mn、Cu、Co的K值在0.4~0.7之间,属于潜在生物可利用性元素。健康风险评价表明:成人的致癌风险比儿童大,尤其Cd对成年人存在潜在的致癌风险,且成年男性高于成年女性;Mn存在潜在非致癌风险,且对儿童的风险最大。

Chemical Speciation of Typical Heavy Metals and Health Risk Assessment in PM2.5 During Winter in Guiyang City

To study the bioavailability and the potential ecological risk of heavy metals to the environment and the human more accurately, PM_2.5 samples were collected in Guiyang City during the winter. The chemical speciation of Cu, Mn, Co, Cd, and Pb in PM_2.5 samples were investigated using the modified BCR sequential extraction procedure. The bioavailability and health risk of the five heavy metals were also estimated based on the results of chemical speciation analysis. The results showed that the different heavy metals in PM_2.5 display different chemical speciation distribution. The Cu was mainly distributed in the acid-soluble fraction, and then the oxidizable fraction. The Mn primarily existed in the acid-soluble fraction, then the residual fraction. The Co was evenly distributed in all the fractions except the residual fraction. The Pb and Cd were almost presented in the acid-soluble fraction. The results of the bioavailability coefficient (K) revealed that the order of bioavailability of the heavy metals was: Cd > Pb > Mn > Cu > Co. The Pb and Cd were classified as bioavailable elements due to K > 0.8. While the Cu, Mn, and Co were remarked as potential bioavailable elements because the values of K ranged from 0.4 to 0.7. The results of health risk assessment indicated that those heavy metals may lead to higher level carcinogenic risk for adults compared with children. The health risk assessment result of Cd indicated potential carcinogenic risk for adult, especially for male adult. Mn may pose potential non-carcinogenic risk to human health, especially for children.