Current level of total element concentrations in the surface layer of Sudburyʹs soils

Published data on soil contamination by Cu, Ni and other elements in the Sudbury mining and smelting region consists largely of scatter sets. In this study, the total elemental concentrations and their spatial distribution in the surface soils of the Sudbury region are presented. Concentrations of Cd, Co, Cu, Cr, Fe, Mn, Ni, S, and Zn in the studied soils were elevated above background levels. Copper and Ni were the primary metallic contaminants in Sudbury soils, with concentrations from 11 to 1890 and 5 to 2150 mg kg−1 for Cu and Ni, respectively. Seventy-five and 62% of the soil samples had concentrations of Cu and Ni, respectively, higher than a ‘critical’ value of 60 mg kg−1. Also, high concentrations of Cd and S occurred in a large proportion of the studied soils. A strong decline in the soil concentrations of Cu and Ni was found as compared to earlier results. The elemental concentrations show great spatial variability, which is related to the effect of the main point sources of contaminants, namely smelters. The spatial distribution of Cu and Ni concentration in the studied soils was strongly correlated. Spatial distribution of Cd concentration in the soils did not follow those of other elements. Cadmium concentrations in the soils were negatively correlated with the levels of other elements and the soil properties. The reduction of atmospheric emissions during the past 20 years, leaching, washing, and erosion processes have contributed to elemental concentration decline in the studied soils.