厦门市郊区PM2.5和PM10中重金属的形态特征及生物可利用性研究

摘要

It is of great significance to explore the migration principle of heavy metal in aerosols, and to evaluate the environmental effect and health effect by analyzing the speciation characteristics of heavy metal in aerosols. The concentrations of Al, Cr, Mn, Ni, Cu, Zn, As, Cd, Pb of four fraction of PM2.5and PM2.5~10in the suburbs of Xiamen were determined by BCR extraction method and ICP-MS .Results showed that the average concentrations of PM2.5 and PM10were (82.48±22.42)μg·m-3 and (50.52±20.48)μg·m-3, respectively, and PM2.5/PM10 ratios ranged from 40% to 70%, with the same seasonal variation of higher in spring and winter, lower in summer and autumn. The speciation characteristics showed the majority of Al,Cr,As existed in oxide and residue form, and Ni, Cu,Zn,Cd and Pb were mainly distributed in acid extractable form, suggested which derived from anthropogenic source. The enrichment factor (EF) and bioavailability factor (K) of Pb and Cd were higher, implying Pb and Cd in aerosols may be more harmful. Analysis of bioavailability and speciation suggested that the less aerosol diameter, the higher concentrations of heavy metals in non-residual fraction, the higher K value and stronger mobility, implied that the heavy metal toxicity of PM2.5.%开展气溶胶中重金属形态特征及其生物可利用性的研究有利于探析大气重金属污染物在环境中的迁移规律，进一步评估大气重金属的环境和健康毒理效应。基于此，该研究采用BCR连续提取法结合ICP-MS测定了厦门市集美区2014年4月至2015年3月为期1年的PM2.5、PM2.5~10（粒径大小在2.5~10μm之间的颗粒物）及其中不同形态金属Al、Cr、Mn、Ni、Cu、Zn、As、Cd、Pb 的含量。结果发现集美区 PM2.5、PM10年平均质量浓度分别为(50.52±20.48)和(82.48±22.42)μg·m-3， PM2.5/PM10比值稳定在40%~70%之间，二者的质量浓度和比值均呈现冬春季高、夏秋季低的季节变化趋势。重金属形态特征结果显示集美区PM2.5、PM2.5~10中的Al、Cr、As的存在形态以残渣态为主；金属Ni、Cu、Zn、Cd、Pb则大量存在于弱酸提取态中，其来源受人为影响显著。这些金属中 Pb 和 Cd 的富集系数（EF）和生物利用有效系数（K）最高，易迁移进入生物体内，毒性危害高。生物有效性和形态特征分析结果表明随着气溶胶粒径的减小，非残渣态的重金属含量增高，K值变大，可迁移转化能力增强，说明PM2.5中的重金属对生物的毒性高于PM2.5~10中的，该现象应引起重视。