北京部分地区降雪重金属污染现状分析

Analysis and Study on Heavy Metal Pollution in Snow Samples from Some Areas of Beijing

为调查北京部分地区降雪中重金属金属元素的污染状况,采集了北京部分地区2011年初2场降雪样品,测定了降雪中Cr、Ni、Cu、Zn、Cd和Pb等6种重金属含量,分析了其污染状况,计算了6种元素的富集系数。结果显示:雪样中重金属含量高低排序为Zn>Pb>Cr>Cu>Ni>Cd,含量最高的元素Zn的浓度范围为:224.50～3 031.25μg/L;含量最低的元素Cd的浓度范围为:6.18～75.35μg/L。Ni、Cd和Pb元素高于地表水质V类标准,Cd和Pb元素高于污水排放标准限值并且污染严重。文章选取Al作为参比元素分析6种元素的富集系数,其均值显示:Cr和Ni的EF710,主要为自然来源,Cu和Zn的EF介于10～500之间,说明其除有自然来源外还有人为干扰,而Cd和Pb的EF值远远大于500,这与机动车燃料中含Pb的情况也基本相吻合,说明生活燃料和机动车燃料的燃烧对于大气环境的恶化有着重要影响。

Concentrations of heavy metals including Cr, Ni, Cu, Zn, Cd and Pb in the snow sampled from some areas of Beijing in the two snowfalls of 2011 were monitored, pollution level and enrich factors （EF） of Cr, Ni, Cu, Zn, Cd and Pb in the snow were analyzed. Results revealed the order of the concentrations in the snow samples from high to low as Zn, Pb, Cr, Cu, Ni, Cd, with the highest and lowest concentration as zinc 224.50-3 031.25 μg/L and cadmium 6.18-75.35 μg/L respectively. Concentrations of Ni, Cd, Pb were higher than Grade V of environmental quality standard for surface water and the concentrations of Cd, Pb more than discharge standard of pollutants for municipal wastewater treatment plant. A1 was chosen to be the reference element in the study to calculate EF of 6 metals, and results showed that EF of Cr and Ni was less than 10, implying that these two elements were entirely from crustal materials or natural process. EF values of Cu and Zn ranged from 10 to 500, which showed the two metals come from both natural source and anthropogenic source, while Cd and Pb had EF values higher than 500, suggesting the sources of the metals are more likely to be anthropogenic.