Distribution of Some Metals in Sediments of the Central Part of the Labe (Elbe) River: Czech Republic

The metals, K, Li, Ca, Mg, Fe, Mn, Co, Ni, Zn, Cu, Cr and Pb were the subject of a distribution study in riverbed sediments of the ≤ 4 μm, 4-20 μm and the total ≤ 63 μm fractions. The method for sequential dissolution was used in order to determine the potential of these metals for transport and uptake by biota. The mineral composition of the fine fractions was characterized by a simple mineral spectrum: mica/illite, quartz, kaolinite dominated; chlorite (± smectite ± vermiculite), calcite, Na-rich plagioclase, K-feldspar and amphibole, in medium to small admixtures; gypsum and pyrite were identified in minor amounts or accessories. Average totals of sequential dissolution from the ≤ 63 μm fractions were 2.03% wt Fe, 1.89% wt Ca, 0.37% wt Mg, 0.22% wt. K; 746 ppm Mn, 458 ppm Zn, 431 ppm Cr, 1030 ppm Cu, 17 ppm Li, 36 ppm Ni, 15 ppm Co and 120 ppm Pb. Metal concentrations were extracted in six steps. In size fractionated samples, K, Li, Mg, Mn, Zn, Co and Pb concentrations, generally increase with decreasing particle size; Cu, Fe, Ca, Cr and Ni were exceptions. Ca, Mn, and occasionally K, Zn and Cr, were concentrated, primarily, in the exchangeable form and adsorbed or in the carbonate phase. The remaining metals were present predominantly in (operationally defined) reducible and oxidizable chemical phases, with contributions from residual phases.