大气降尘中重金属元素及铅同位素分析

Analysis of Heavy Metal Pollution in Atmospheric Deposition

针对重金属污染溯源问题,以某工业区为例,用测定大气降尘中重金属浓度与同位素比值的方法探寻污染来源及污染传播途径.通过采集当地大气降尘、土壤背景、植物、矿石和煤渣样品,进行重金属元素含量和铅同位素比值分析.结果表明：大气降尘中重金属Pb、Zn、As、Cu含量远大于土壤背景值,且相关性明显、空间分布相似;沿河沟方向Pb、Zn含量与距冶炼厂距离呈负相关,推测重金属污染与冶炼厂有关;而As含量在电厂附近略有增高,认为电厂对重金属As有一定贡献,为复合型污染;同位素分析显示,冶炼厂煤渣、淬水渣样品与大气降尘样品铅同位素组成相似,表明降尘中重金属铅主要来源于冶炼厂,电厂对降尘中铅元素积累影响不大;大气降尘与植物样品铅同位素组成相当,大气降尘中重金属对工业区周边小麦污染的贡献率为89％～92％.

The concentration of heavy metals in atmospheric deposition and the isotope ratio method are used to trace the source and dispersion of the heavy metal pollution of the air in a typical industrial area. Atmospheric deposition, soil, plants, ore, and coal cinder samples are collected and analyzed for the concentrations of heavy metals and the isotope ration of lead. The results show that the concentrations of the Pb, Zn, As, Cu in atmospheric deposition are larger than soil background levels, and have an obvious correlation with the soil background levels and that both values have a similar spatial distribution. It is found that the nearer the smelting area, the heavier the concentrations of heavy metals in the atmospheric deposition, and shows that the pollution source is the smelting. It is also found that the heavy metals come from a power plant, and is a compound pollution. Analyses of lead isotopes show that the lead isotope compositions in atmospheric deposition are similar to those in ores and the coal cinder, and that the main pollution source of lead is the smelting, and the power plant has a little effect on Pb deposition accumulation. Furthermore, the atmospheric deposition and plants have similar lead isotope compositions, and the contribution rate of the heavy metals in atmospheric deposition to the plants is 89 %-92 %.