Characteristic and evaluation of soil pollution by heavy metal in different functional zones of Guangzhou.

Objective To investigate and analyze the heavy metal pollution in soil in different functional zones of Guangzhou. Methods The commercial areas, bus stations, residential areas, cultural and educational areas, medical service areas and parks in Guangzhou were taken as the research objects, the soil samples were randomly collected by triple subsampling technique in each functional zone. The contents of Pb, Zn, Cu, Ni, Mn were determined by AAS, and the contents of As, Hg were determined by AFS. The relationship of heavy metal was analyzed with Pearson correlation analysis. The pollution of heavy metal was assessed with Nemerow comprehensive pollution index. Results The mean contents of heavy metals in soil samples from different city zones of Guangzhou exceeded the related background values in Guangdong province. The mean contents of Hg and As were 16.28 and 14.64 times respectively as high as those background values in soil in Guangdong. The contents of Cu, Zn, Pb, Cd, Ni and As were dominant in commercial areas, Mn was dominant in residential areas, Hg was dominant in urban parks. There was a significant difference in the level of Cu, Zn, Pb and Hg among different city zones (P0.05). There were positive correlations among Mn, Cu, Zn, Pb and Ni , among Cu, Zn, Pb, Cd and Ni, and among Cu,Pb and Hg (P0.05), respectively. The Zn, Cd , Hg pollution was the severest among different functional zones. The Nemerow comprehensive pollution indexes ranked as follows: urban park (18.13) commercial area(15.85)residential area(13.34)bus station(10.75) education area (8.98) hospital area (9.61). Conclusion The urban soil in Guangzhou has been polluted by heavy metals.