贵州典型酸雨城市降尘中有毒重金属时空分布及来源分析

对2012年贵阳、遵义、安顺市区和背景点降尘样品进行逐月采集,并利用微波消解、ICP-MS对降尘中Cr、As、Cd、Hg、Pb的含量进行测定,分析其来源与贡献。结果表明,降尘五种重金属元素中,Pb含量最高,Hg含量最低。与土壤背景值相比,除Cr外,其它四种重金属元素含量总体明显升高;As、Cd、Hg含量季节性变化明显,Cr、Pb不明显。从降尘中五种重金属元素总量看,安顺夏季最高,市区点降尘总量均高于背景点,遵义和贵阳冬季最高,且在秋冬季背景点含量高于市区点。相关系数和主成分分析表明,贵阳、安顺、遵义降尘中重金属污染均受燃煤影响,其贡献率分别为61%、35%、75%。此外,安顺市交通尘贡献率为50%,遵义市风沙扬尘贡献率为21%。与其他城市相比,研究区城市降尘重金属元素除Cr外,As、Cd、Hg、Pb含量均较高。

Analysis of the Temporal and Spatial Variations and Sources of Toxic Heavy Metals in Atmospheric Dustfall in Typical Acid-Rain Cities, Guizhou Province

Dustfall samples were collected at urban and background sites monthly in Guiyang, Zunyi, and Anshun in 2012, the contents of Cr, As, Cd, Pb and Hg in the dustfall samples were determined by means of microwave digestion and ICP-MS, and their sources and contributions were analyzed. The results showed that the content of Pb was highest among the five heavy metals in dustfall, and that of Hg was lowest. In comparison with the background of soil, the contents of the four heavy metals were obviously higher as a whole except for Cr. The contents of Cd and Hg changed obviously with the seasons, those of Cr and Pb showed no trend of seasonal variation. The total amount of the five heavy metals in dustfall in Anshun City was highest in summer, which was higher in urban site than in background site, whereas that in Zunyi and Guiyang was highest in winter, the content in the background site in autumn and winter was higher than that in the urban site. The results of correlation coefficients and principal component analysis showed that heavy metal pollution in dustfall in Guiyang, Zunyi, Anshun cities were mainly affected by coal-combustion, and the contribution rates were 61%, 35% and75%, respectively. In addition, the contribution rate of transportation dust in Anshun City reached 50%, and that of aeolian dust in Zunyi City accounted for 21%. In comparison with other cities, the contents of As, Cd, Hg and Pb in dustfall in the study cities were relatively high except for Cr.