HEAVY METAL CONCENTRATION IN RURAL SOILS: A CASE STUDY IN PAMPEAN SOILS (ARGENTINA)

Resumo

Background values for heavy metals were proposed in Azul (Argentina), a representative agricultural-grazed grassland area of South America, as a basis to identify and assess soil pollution processes at regional level. Forty-two top soils were sampled and heavy metals concentrations were analysed for seven elements (Cd, Co, Cr, Cu, Ni, Pb, and Zn) with an ICP-MS after acid digestion. The background values were in mg kg^-1: Cd 0.15, Co 10.8, Cr 22.1, Cu 39.2, Ni 13.7, Pb 11.8 and Zn 133.9. Once the background upper limits were established, a few points with anthropogenic signatures were observed. The heavy metal showing the greatest number of samples with enrichment anomalies was Cd. The greatest enrichment anomalies in Cd, Cr, Cu, Ni, Pb and Zn were detected in the grassland top soil due to an unauthorized rubbish dump. The slight anomalies from cropped lands could be due to an incipient anthropogenic contamination.