Distribution of Pb, Zn and Cd in stream and alluvial sediments in the area with past Zn smelting operations

Abstract

AbstractThe sources of Zn, Pb and Cd in alluvial and stream sediments have been studied in the area of historical Zn smelting tradition. 30 samples of stream sediments and samples from 4 alluvial sediment profiles were collected. Fractions 0.125–0.063 and < 0.063 mm were analysed by the means of ICP-MS prior 4-acid digestion. The highest levels of Zn, Cd and Pb were detected in the alluvial sediments in the closest vicinity to the abandoned slag and ore roasting residue waste dumps, reaching 96 and 4520 mg/kg, 522 and 26,800 mg/kg and 3.7 and 31 mg/kg for Pb, Zn and Cd in stream and alluvial sediments, respectively. The Voglajna River then transports contamination particles into the Savinja River, which afterwards flows into the Sava River. Consequently, the anomaly can even be detected in the Sava River, more than 30 km downstream. Higher levels of Pb, Zn and Cd have been found in fraction < 0.063 mm compared to 0.125–0.063 mm fraction. Impacts of historically contaminated soil erosion and in particular the wash-out of Zn-smelting waste from the improperly managed waste dump were recognised as the dominant sources of Zn, Cd and Pb in the stream and alluvial sediments.