Risk grade assessment for farmland pollution of heavy metals in Beijing

In order to fully investigate the environmental pollution risks of Heavy Metals and its spatial distribution in Beijing cultivated soils，environmental risk of Cr, Ni, Cu, Zn, As, Cd, Pb and Hg in 1018 soil samples were evaluated using Hakanson potential ecological risk index, and the probability distribution maps of their risk were produced by indicator Kriging method, also their spatial distribution were analyzed. The results showed that the heavy metals’ environmental risk of Beijing reached medium level and low level, and the respective samples ratio of low, moderate, severe and very serious risk level was 42.63%, 34.97%, 18.57% and 3.83%. The risks of Cd and Hg were at a higher level, the risks of Cr, Ni, and Zn were relatively slight. Risk probability map indicates that the urban fringe around the city, Daxing, Tongzhou, and Miyun are in the high-risk areas.