Evaluation of heavy metal contamination in sediments using the method of total digestion and determination of the binding forms-Tisa River Basin, Serbia

This paper describes an approach for the evaluation of metal contamination in sediment, using the determination of binding forms of elements (sequential extraction method), the total element content (digestion method), as well as a comparison of the obtained results with the legislative limits of the EU. Results indicate that silicates are significant substrates for Ni and Cr, whereas Zn, Cd, Pb, and Cu were not dominantly bound to silicates. Mg is present in the form of carbonates and silicates; Fe is in the form of oxides, and Mn is in the form of Mn carbonate and oxides. Zn, Cd, and Cu are dominantly extracted in the labile fractions and because of this they are likely to pose a direct and significant threat to the environment. The results of a comparison with the legislative limits of the EU indicated that in some of the sediments, elevated levels of Zn, Cd, and Cu exist. The contamination was caused by permanent pollution, originating mainly from industrial activities, municipal sewage discharge and agriculture. Results indicate to the significance of the employment both of methods, sequential extraction and total digestion, for metal investigation in sediment. With the aim of protecting the sediment quality of the Tisa River, of importance for Central Europe, the obtained results also indicate the necessity for systematic investigations in all countries through which this river flows