Comparison of various digestion and extraction procedures in analysis of heavy metals in sediments

Sediment analysis is very important in investigations of the heavy metal bu rden in the environment. In the present work various digestion and extracti on procedures were evaluated in order to assess the extent of contamination with heavy metals in sediments from the Moste hydroelectric reservoir. Tot al acid dissolution, aqua regia digestion and acetic acid extraction proced ures were applied to samples. Zn, Cd, Pb, Co, Ni, Cu and Cr were determined by flame or electrothermal atomic absorption spectrometry (FAAS, ETAAS) un der optimized measurement conditions. A comparison of total acid dissolutio n including hydrofluoric acid (HF) treatment and the aqua regia soluble fra ction was made to estimate the applicability of aqua regia digestion in ana lysis of total metal concentrations in sediments. In general, good agreemen t of the results was observed for Co, Pb, Cu and Zn, however for Cr, Ni and Cd significantly lower results were obtained in the aqua regia soluble fra ction. In addition, an extraction procedure using 25% v/v acetic acid was a pplied for estimation of the extent of contamination with heavy metals orig inating from anthropogenic activities. The results indicate that the sedime nts upstream of the reservoir are not contaminated, while the sediments fro m the hydroelectric reservoir shows a significant anthropogenic input of Ni , Zn and Pb, which corresponds well with pollution sources.