Fractions of heavy metals in soil after the application of municipal sewage sludge, peat, and furnace ash / Frakcje metali ciężkich w glebie po zastosowaniu komunalnego osadu ściekowego, popiołu paleniskowego i torfu

Abstract

Abstract The effect of addition of different materials, i.e. sludge, ash and peat, as well as different doses of mixtures of ash and sludge and ash peat, on the total content of heavy metals (Cr, Zn, Pb, Cu, Cd, Ni) and their fractions was studied. Application of municipal sewage sludge, ash-sludge and ash-peat mixtures in the experiment caused a gradual increase in the content of studied heavy metals in soil. The ash was characterized by a low content of heavy metals as compared to municipal sewage sludge. After application of peat and its mixtures with ash a decrease of content of heavy metals was observed, and when the peat was used alone the greatest increase in the organic C content in the substrate could be seen. Distribution of heavy metals in the fractions separated in different combinations shows large variations, depending on the tested metal and the studied variant. Chromium, zinc, lead, and cadmium have been accumulated mainly in the residual fraction (FV), and most of the copper and nickel have been specifically bound with organic matter (FIV). It has been found that the alkaline materials application to the soil decreased the solubility of most heavy metals, which results in a limitation of their uptake by plants. Chromium and copper were an exception, since their solubility increased with the alkalinity of the substrate. An exception was chromium and copper, which solubility increased with the alkalinity of the substrate.