Heavy metals contamination in soils around tailing heaps with various degrees of weathering in Zimapan, Mexico

摘要

Dispersion of mine tailings is the main cause of heavy metal (HM) contamination in soils in Zimapan, Mexico; however, the extent of this problem has not been assessed. Therefore, the aims of this study were to determine the degree of contamination and to assess the influence of mine tailings with different degrees of weathering on the spatial distribution of HM in soils. Soil and mine tailing sampling was carried out. The HM concentration was determined by atomic absorption spectrophotometry; spatial analysis and the size of the contaminated areas were calculated using GIS software; the mine tailings were characterized physically, chemically and mineralogically. The results suggest that all the tailing heaps have contributed to the HM dispersion. High HM concentrations were founded in soils around mine tailings (9402 mg kg~(-1) Pb and 52 mg kg~(-1) Cd). Surface area contaminated with Pb and Cd was estimated at 6.2 and 2.7 km~2, in urban soils, respectively.