株洲市大气降尘中元素特征及来源分析

为研究湖南省株洲市大气降尘中多种元素的分布特征以及来源,于2012年1~12月对株洲市12个点的大气降尘样品进行采集并对其中28种元素的含量进行分析.结果表明,株洲市城区各采样点大气降尘年沉降量为23.14~114.67 g·m~(-2),其中工业区和商住混合区年均值分别为89.46 g·m~(-2)和33.20 g·m~(-2),低于其它工业城市;工业区和商住混合区降尘中分别有10种元素(Na、Mg、Al、K、Ca、Ti、Mn、Fe、Zn、Pb)和8种元素(Na、Mg、Al、K、Ca、Ti、Fe、Zn)含量大于1 000 mg·kg~(-1),其中工业区2种重金属元素(Zn、Pb)含量超过10 000 mg·kg~(-1),远高于地壳中的含量.株洲市大气降尘主要来源为金属冶炼、地表扬尘、汽车尾气、建筑粉尘和与Mo、Ba元素相关的工业生产.相关性分析、主因子分析和迁移特征分析表明降尘中Mn、Fe、Co、Cu、Zn、As、Se、Ag、Cd、Sn、Sb、Tl、Pb等13种元素主要来自株洲市工业区废气排放,其中Cu、Zn、As、Ag、Cd、Se和Pb等7种元素污染严重,工业区重金属元素含量是土壤背景值中含量的7.4~4 079.4倍,商住混合区是土壤背景值的3.6~1 413.4倍,背景比值最高的为Cd元素.工业区的污染程度明显高于商住混合区.

Characteristics and Sources of Elements in Atmospheric Dust Fall in Zhuzhou City, Central China

To study the concentration characteristics as well as sources of elements and heavy metal pollution in atmospheric dust fall in Zhuzhou City, 144 samples from 12 sites in the Zhuzhou urban area were collected from January to December in 2012 and 28 kinds of elements in the samples were analyzed. The results showed that the dust fall quantities of the industrial areas and mixed commercial and residential (MCR) areas were, respectively, 89.46 g·m^-2 and 33.20 g·m^-2 and the range of all sample points was 23.14-114.67 g·m^-2. There were 10 elements (Na, Mg, Al, K, Ca, Ti, Mn, Fe, Zn, Pb) in the industrial areas as well as 8 elements in the MCR areas, for which the contents greatly exceeded 1000 mg·m^-1 in the atmospheric dust fall. The Zn and Pb contents exceeded 10000 mg·kg^-1 in the dust fall of the industrial areas, which were far higher than those in the Earth''s crust. The main sources of dust fall in Zhuzhou City were metal smelting, shallow ground dust, vehicle emissions, construction dust, and industrial production with specific elements (Mo, Ba). Correlation analysis, principal component analysis (PCA), and analysis of transportation characteristics showed that 13 elements (Mn, Fe, Co, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Tl, Pb) in dust fall mainly came from waste gas emissions of industrial areas in Zhuzhou, in which 7 heavy metal elements (Cu, Zn, As, Ag, Cd, Sb, Pb) caused serious pollution. The contents of heavy metals in the industrial areas were 7.4 to 4079.4 times the contents defined in China soil elements background values, whereas those in the MCR areas were 3.6 to 1413.4 times the soil background values. Cd was the highest background ratio element. The degree of contamination was clearly higher in the industrial areas than in the MCR areas.