The Heavy Metal Content Character of Agricultural Soil in the Pearl River Delta

The distribution of heavy metals in agricultural soils in the Pearl River Delta was investigated. 212 topsoil samples were collected in the research area. The total content and available content of 8 heavy metals (Cu, Pb, Zn, Cr, Ni, Cd, As, Hg) in the soils were determined. The results show that: the contents of all the eight heavy metals are over the national and local soil standard, with the largest three being Zn, Cd and Hg. Among the 8 heavy metals, Cd has the highest ratio of available content to total content while Hg has the lowest. The average ratios of Cd and Hg are respectively 45.58% and 0.41%. The available content of heavy metals has positive relationship with the total content. The heavy metals pollution in soil of the Pearl River Delta is mainly caused by traffic, sewage irrigation, industries pollution, municipal garbage and sludge sewage.