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.