Distribution of trace metals in surface water and streambed sediments in the vicinity of an abandoned gold mine from Hunedoara County, Romania

Abstract

The present study investigates the distribution of some toxic metals such as As, Cd, Cu, Cr, Co, Hg, Ni, Pb, Ti within sediments and surface water from Baiaga stream, situated near an abandoned mining site from Certeju de Jos, Hunedoara County, in the vicinity of two mining sterile dumps and Coranda Pit. The entire studied area indicates an acid pH, both in surface water and sediments. Mobile metallic concentrations were evaluated using first step of BCR 701 sequential extraction modified scheme. The total and mobile content of metals from sediments were determinate using inductively coupled plasma optical emission spectrometry. Calculated bioavailability index (Ibio) was used in order to correlate the presence of toxic metal in surface water. The experimental data shows important concentrations of metals (Cd, Co, Cu, Ni, Pb) in surface water correlated with relatively high bioavailability index, that include the surface water in fifth quality class (the worst) according to Romanian Order 161/2006. Low content of metals (As, Hg, Ti) in surface water despite the high concentrations presented in sediments represents the effect of lack of mobility (Ibio less than 0.1%). The bioavailability index represents a useful tool for sediment control in acidic mining sites.