Source Identification of Trace Elements in Peri-urban Soils in Eastern China

The source identification of trace elements in peri-urban soils has not been fully explored, especially for the areas in eastern China. Here, 80 soil samples, including 40 from cropland, 11 from orchards and 29 from forests, were collected in a typical peri-urban catchment, Ningbo, eastern China. The concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn), Pb isotopes and basic soil properties were measured for each soil sample. Multivariate analysis of correlation, regression, principal component analysis and isotopic tracers were used. The results showed that the concentrations of trace elements significantly differed based on land uses, especially for Cd, Cu and Zn. For the seven trace elements, the Cd, Cu and Zn in crop soils are contaminant elements. In the peri-urban soils, Cr and Ni are dominated by parent material and paedogenic processes. Difference in As and Pb concentrations between land uses maybe attributed to atmospheric deposition induced by fossil fuel combustion. Applications of fertilisers, calcium phosphate and calcium superphosphate, livestock manure and compost, are the dominant sources of pollutants in peri-urban soils, especially for Cd, Cu and Zn, indicating the key point for pollution control for this area. Calcium and P are effective indicators of Cd, Cu and Zn contamination for the peri-urban catchment.