天津市PM_(2.5)分布特征及重金属化学形态分析

Distribution Characteristics of PM_(2.5) and Analysis on Chemical Speciation of Heavy Metals in Tianjin

通过采集天津市大气颗粒物样品,研究了颗粒物浓度及粒径分布随时间变化的特征,并采用改进BCR法对PM2.5中重金属的形态进行了分析。结果表明:PM2.5浓度冬季明显高于其他季节;PM2.5与PM10的比例冬季最高,夏季次之,春、秋季节基本持平;PM2.5中Cu、Zn、Pb、Cd主要以弱酸提取态存在,Cr以可还原态、残渣态为主要形态,Ni主要以可氧化态、残渣态形态存在;6种元素中,Cd、Zn生物有效性最高,Pb、Cu生物有效性居中,Ni、Cr生物有效性最小。

For the purpose of analyzing the concentration and size distribution of atmospheric particles,atmospheric particle samples are collected and the chemical speciation of heavy metals is also studied by improved BCR method.The results indicate that the mass concentration of PM2. 5in winter is much higher than that in spring,summer and autumn. The values of PM2. 5/ PM10（ mass concentration ratio） change with the season,descending in the following order： winter,summer,spring and autumn. In PM2. 5,Cu,Zn,Pb and Cd exist mainly in organic form,Cu,Zn and Cd exist mainly in acid extractable,Cr exists mainly in reducible form and silicate form and Ni exists mainly in oxide form and silicate form. Among all the 6 heavy metals,the bioavailability of Cd and Zn is the highest,the second is Pb and Cu and the last is Ni and Cr.