Spatial, sources and risk assessment of heavy metal contamination of urban soils in typical regions of Shenyang, China

Surface soil samples from 36 sampling sites including different functional areas in seven districts of Shenyang, China were collected and analyzed. The results showed that the average concentrations of Cd, Cu, Pb and Zn in soil of Shenyang were up to 0.42, 51.26, 75.29 and 140.02 mg/kg, respectively, which are much higher than their natural background values. Among the functional areas and administrative regions, the industrial regions and the Tiexi District displayed the highest metal concentrations. Pearson's correlation analysis showed that there existed close correlations among Cd, Cu, Pb and Zn (except for Cd-Cu) at 1% level. Principal Component Analysis (PCA) coupled with correlation between heavy metals revealed that heavy metal contamination might originate from traffic and industrial activities. The values of pollution index (PI) and integrated pollution index (IPI) indicated that metal pollution level was Pb > Cd > Zn > Cu, and Cd, Cu, Pb and Zn belong to moderate or high pollution level. Potential ecological risk indexes (RI) further indicated that Shenyang was suffering from serious metal contamination. These results are important for the development of proper management strategies to decrease non-point source pollution by various remediation practices in Shenyang, China.