石家庄市大气降尘重金属元素来源分析

An analysis of the sources of heavy metals in atmospheric dustfall of Shijiazhuang City

本文对石家庄市大气降尘重金属含量水平进行了研究,从2007年11月起连续收集一年的大气降尘样品,分析了As、Cd、Hg、Pb、Cr、Cu、Zn、Ni、Mo、Mn、Al2O3、K2O等12项。结果表明,与土壤背景值相比,石家庄市大气降尘中除Al2O3外的重金属含量总体明显升高。采用相关分析和主成分分析,对降尘重金属元素来源进行解析,认为有3种主要来源:一是Pb、Cr、As、Hg、Mo、Cd、Mn与燃煤活动、道路交通有关;二是Ni、Cu、Zn除与燃煤活动有关外,还与工矿企业废气排放有关;三是Al2O3主要与土壤颗粒物有关(自然来源)。以Al作为参考元素计算重金属的富集因子表明,受工业活动影响的Cd、Hg、Zn具有较大的富集因子,大气降尘中的重金属含量高值区与工业区域的分布相吻合。

Fifty-one atmospheric dusffall samples were collected successively from November 2007 to November 2008 in Shijiazhuang. All dustfall samples were analyzed for concentrations of As, Cd, Hg, Pb, Cr, Cu, Zn, Ni, Mn, Mo, Al2O3 and K2O. The results indicate that, compared with the background values of soil in Shijiazhuang area, atmospheric dustfalls have elevated metal concentrations on the whole, except for the concentration of Al2O3. Correlation coefficient analysis and principal component analysis （PCA） were performed and three main sources were identified： （1） Pb, Cr, As, Hg, Mo, Cd and Mn, which are mainly derived from coal combustion and traffic pollution; （2） Ni, Cu and Zn, which are probably related not only to coal combustion but also to factory exhaust; （3） Al2O3, which is mainly derived from soil particles. Based on concentration analysis and correlation analysis, the authors selected Al as the reference element to calculate the heavy metal enrichment factors （EFs）, which in turn further validated the source identification. However, industrally enhanced Cd, Hg and Zn show maximum enrichments. Therefore, EFs shed a light on the level of human influence on atmospheric dustfalls. High concentrations of heavy metals in atmospheric dustfalls are consistent with the distribution of the industrial area.