Zur Ermittlung der Bindungsformen von Haupt- und Spurenelementen in Sedimenten durch sequentielle Löseverfahren

A modified procedure after Tessier in comparison with a leaching sequence developed for the speciation of phosphorus (Psenner et al.) is applied to some constituents of river sediments to prove the predicted fractionation pattern. Mica, clay minerals, carbonates, sulfides, humic acid, worms and plants have been used as test substances. In addition, the procedures have been applied to sediments before and after the input of municipal effluents, to test the pathway of the input. Al, As, Co, Cr, Cu, Fe, K, Mg, Ni, Pb, P and Zn have been determined in the leachates. Living biomass, like oligochaeta and plant material, releases most of its contents in the first solution applied, where death occurs, thus rendering “exchangeable” material. Humic acid is resistant and needs competition with oxalate or decomposition with H2O2. Humic acid is found mainly in bicarbonate/dithionite. Concerning the carbonates, dolomite is not found in the so called “carbonate fraction” of acetate buffer pH=5.5, but in 25% acetic acie, whereas all carbonates are found together in dilute HCl. Among the silicates, biotite and chlorite are partially soluble in hot HNO3 without the need of HF. The clay minerals are very resistant, only small amounts are exchangeable. Sulfides are found after oxidation with H2O2 or with HNO3 or in the other sequence partially in dilute HCl and in hot NaOH. The municipal input of heavy metals and phosphate passes into different fractions, according to individual affinity. To avoid systematic errors of one sequence innatural samples, a combination of both techniques is recommended.