Sources and Ecological Risk Assessment of Heavy Metal(loid)s in Agricultural Soils of Huzhou,China

To identify sources of heavy metal(loid) (HM) contamination in agricultural soils of Huzhou, surface soil samples were sampled from 89 different agricultural regions in 2012. Concentrations of heavy metal(loid)s, along with pH, total phosphorus (TP), total nitrogen (TN), and soil organic matter (SOM), were determined. Ecological risk was then assessed using a modified Hakanson ecological risk index, and the sources of contamination were determined using principal component analysis (PCA). Mean concentrations of heavy metal(loid)s were 10.26, 23.21, 83.75, 22.81, 0.25, 61.86, 33.03, and 0.15 mg kg^?1 for As, Cu, Zn, Ni, Cd, Cr, Pb, and Hg, respectively. Cu, Zn, Ni, Cr, Cd, Hg, and Pb were correlated positively with TP and there were obvious positive correlations among Cu, Zn, Ni, Cr, and Cd. Risk index (RI) values varied from 39 to 1246 with a mean value of 137. Enrichment of Pb, Zn, Cu, and especially Cd can be attributed to excessive use of nitrogen and phosphorus fertilizers containing heavy metals, as well to surface irrigation and natural soil formation. While the ecological risk of most agricultural soils in Huzhou is low, it is recommended that the use of phosphate and nitrogen fertilizers be restricted and production technology be improved to reduce the heavy metal(loid) concentrations. Results suggest that the Chinese environmental quality standard for soil should be revised to better address heavy metal(loid) contamination.