Comprehensive analysis of heavy metals in soils from Baoshan District, Shanghai: a heavily industrialized area in China

The potential for soil heavy metal contamination in high risk areas is a crucial issue that will impact the environment. Soil samples were collected in 2003 and 2007 to investigate heavy metal contamination characteristics and pollution changes in the industrialized district of Baoshan (Shanghai, China). Both multi-statistic and geostatistic approaches were used and proved to be useful in the interpretation of the analytical results. The potential for soil contamination in the high risk areas presents a crucial issue that will impact the environment. The results indicate that soil in the Baoshan District is alkaline. Additionally, the accumulation of heavy metals in the soil increased between 2003 and 2007. The study results indicated that the concentration of the metals lead (Pb), chromium (Cr), cadmium(Cd), mercury (Hg), arsenic (As), zinc (Zn) and copper (Cu) in the soil has great discrepancy, especially of Pb and Cr. The concentrations of Pb and Cr in the soil show significant difference between two observed years (p < 0.05). The concentration of most of these metals was higher in 2007 than 2003. Only the concentrations of Cd and As were not higher in 2007. Traffic and industrial contaminants were the likely source of Pb and As; Hg largely came from agricultural contamination, household garbage and industrial contamination; Cd, Cr, Zn and Cu mainly originated from industrial activities. Multivariate statistical analyses showed that human activities mainly contributed to heavy metal contamination. Spatial distribution confirmed this by showing that areas with the highest metal concentrations occurred where there were high levels of industrial activity and traffic. Potential ecological risk assessment results showed that high risk zones were highly correlated with spatial analysis. The study estimated that in 2007, 85.2 % of the district could be categorized as high risk, which is 77.4 times more than that in 2003.