SPATIAL DISTRIBUTION CHARACTERISTICS AND ASSESSMENT OF HEAVY METALS IN URBAN SOIL OF GUIYANG CITY, CHINA

A detailed investigation was conducted to understand the contamination characteristics of a selected set of heavy metals (HMs) in Guiyang. The amount of Hg, Cd, As, Pb, Cr, Cu, Ni and Zn were determined from 82 soil samples collected within urban area. The HMs spatial distribution analysis based on ArcGIS, and the geo-accumulation (I-geo) and potential ecological risk index (E-r(i), & RI) were employed for evaluation. Results showed that the mean concentrations of investigated HMs except Pb and Cr in urban soil exceeded their background values. The distribution characteristics of Cd, As and Pb in urban soil elevated concentrations from northwest to southeast, Hg mainly concentrated in the south part, Cr and Zn concentrated in northeast and southeast parts, however, The regions with higher Cu and Ni concentrations were sporadic-like distribution in the study. The values of I-geo indicated that HMs contamination level was Cu > Zn > Cd > Ni > As > Hg > Pb > Cr, and Cu, Zn and Cd were at uncontaminated to moderately contaminated. The average values decreased in the order of Hg > Cd > Pb > As > Cr > Ni > Cu > Zn, Hg was at moderate to considerable ecological risk level, while other HMs had low risk levels. The average value of RI was 105.43 and belonged to low potential ecological risk level. The findings of this study may will be significance for both local residents in taking protective measures and local government in alleviating HMs pollution in urban soil.