Soil contamination by heavy metals is a current concern that requires a suitable approach, taking the needs of modern societies into account. In mined areas the evaluation of soil contamination is an important tool for the management of degraded areas. This study was carried out in order to establish local reference values (LRV) for Zn in soils surrounding mining areas in the county of Vazante-MG (Brazil), with a view to evaluate the environmental contamination. Soil profiles were collected in the mining areas, and both upslope and downslope and sampled at depths of 0-2, 2-5, 5-10, 10-20, 20-50, 50-100 and 100-150 cm. Total concentrations and available forms (Melich-3 and DTPA) of Zn were determined. LRV was obtained by the mean of total Zn contents in the 0-20 cm layer of the profiles in upslope position. Based on the LRV, the contamination factor (CF) and the geoaccumulation index (GI) were calculated for each profile. The LRV determined for Zn was 1262 mg kg-1, which is a very high content when compared to quality standard values and suggests monitoring and restrictions in the agricultural and residential soil use. Nevertheless, the LRV is lower than the intervention values for industrial areas established in the State of São Paulo, USA and Canada. The CF was higher in soils of the mined area, mainly in profile 5 of the mining area. Based on the GI, the profiles located downslope were classified as moderately contaminated to not contaminated.
contaminated soils; guide values; Zn background level
