北京城区表层土壤多元素分布特征及重金属元素污染评价

采用地统计学和GIS相结合的方法,对北京城区表层土壤样品54项指标的地球化学背景值进行了详细研究,认为微量元素中Ni、Cr和As含量值存在极高值点,具有点源污染特征;Hg、Cd、Zn、Pb和Cu具有面状污染特点。对这5种重金属元素开展研究,统计北京城区五环内每个区域的数据并结合元素含量空间分布特征,指出元素含量平均值由市中心向周边地区逐渐降低。采用内梅罗指数法对表层土壤重金属元素污染进行评价,认为北京市城区表层土壤大部分已经被重金属元素所污染。分析了造成土壤重金属元素污染的可能影响因素,主要包括工业活动、化石燃料燃烧、建筑涂料、机动车尾气等,并提出了污染防控的建议。

The distribution of surface soil elements and the pollution assessment of heavy metal elements in Beijing

A detailed study of geochemical background values of 54 indicators for surface soil samples in Beijing City was carried out by using geostatistics and geographic information system (GIS). The result shows that Ni, Cr and As values are extremely high, which points to pollution from point source, while Hg, Cd, Zn, Pb and Cu concentrations are indicative of planar pollution. In addition, the further research on the five heavy metal elements shows that the average concentrations of these elements gradually decrease from the downtown to the peripheral area, based on data from the whole region within the Fifth Ring Road and the characteristics of spatial distribution of elemental content. Nemerow pollution index method was employed to evaluate the degree of heavy metal pollution in the surface soil. It is concluded that most of Beijing urban surface soil has been contaminated by heavy metals. Moreover, the probable causes for pollution from the heavy metal elements are identified, which mainly include industrial activity, burning of fossil fuels, architectural coatings, exhaust from motor vehicles, etc, and some suggestions for prevention and control of the pollution are put forward.