Distribution and assessment of trace elements contamination in sediments of Conceição River basin, Brazil

Abstract

The Conceição river basin, in Iron Quadrangle, Brazil had a long mining history which dates back to the late 17th century with large gold and iron mines. These activities may be associated with river sediments contamination by trace elements, which were evaluated in this paper by En-richment Factor (EF) and Contamination Factor (CF). Potential ecological risks, by combining sediment quality control guidelines (SQCG) and potential ecological risk index (Er and RI) were presented. Anomalous values for As (92.5 mg.kg-1), Cd (22.49 mg.kg-1), Cr (2582 mg.kg-1), Cu (65.9 mg.kg-1), Pb (58.6 mg.kg-1) kg) and Zn (133.4 mg.kg-1) are observed. EF and CF indicate contam-ination by Cd, Cr, Fe, Mn, Zn and Ni in at least one point, with the highest values for Fe and Mn are downstream of iron mines, Cr and Ni are close to the gold mines. According to the SQGC and Er, As, Cd, Ni, and Cr are the most probable to result in adverse effects on sediment-dwelling organisms in this study. The results of the principal component analysis (PCA) indicate distinct lithological units as sources of the analyzed elements, that associated with the indicators, made it possible for the first time to delimit and classify the high concentrations of some analyzed ele-ments as contamination in the Conceição river basin.