Spatial distribution, sources, and risks of heavy metals in soil from industrial areas of Hangzhou, eastern China

Heavy metal (HM) pollution in soil is an inevitable outcome of industrialization. Quantitating the distribution of this pollution—on, e.g., local and regional scales—is an important step in remediation and prevention. The present study investigated HM pollution in the soil of the industrial zone of Hangzhou, Zhejiang Province; specifically, analyzed the HM concentrations, spatial distribution, sources, and potential ecological and health risks. A total of 2651 soil samples were collected; and the levels of As, Cr, Cu, Pb, Hg, Ni, Cd, and Sb were determined. The average concentrations of these HMs were all lower than the national construction land soil pollution risk screening values; but the average levels of As, Cu, Pb, Ni, and Cd exceeded the background values of soil HMs in Zhejiang Province. By analyses of the spatial distribution in combination with a positive matrix factorization model, 84.6% of soil HM pollution in the study area was related to human activities, and 15.6% was from natural sources. Affected by human activities, there were large differences in the spatial distribution characteristics of various HMs. The potential ecological hazard index method and a health risk model were adopted to assess the ecological and human health hazards in Hangzhou. The mean value of the potential ecological risk index (PERI) of HMs was 407.54, indicating a high ecological risk; Cd (PERI: 323.4) might be the main pollution risk element of soil in this area. The carcinogenic and noncarcinogenic risk indices were typically within an acceptable range.