The objective of the paper is establishing of eco-chemical characterization of the river system by investigating and distribution heavy metal content in the river sediments using sequential extraction and total digestion. Heavy metals toxicity and bioavailability in the Danube river sediment are defined according to their distribution between different phases. Sediments samples were taken from 9 sites and analysed for cadmium (Cd), iron (Fe), manganese (Mn), lead (Pb), copper (Cu), zinc (Zn) and chromium (Cr), and the results about cadmium and iron presented in this paper.

This study investigates the possibilities of using Lagenaria vulgaris biomass as a biosorbent for removal of heavy metals from wastewater and natural water. The experiments were carried out with model solutions of Pb2+, Cd2+, and Zn2+, in batch system. The effects of contact time, temperature, initial metal concentration and adsorbent doses, on the adsorption of heavy metals have been studied. Results show that biosorbent based on Lagenaria vulgaris represent efficient and low-cost means for pretreatment of heavy metals contaminated waters.

In this work, the horizontal and vertical distribution of metals in the sediment of the DTD canal was studied, in a 6 km long polluted section between Vrbas and Bezdan. The assess sediment quality and the bioavailability of heavy metals, sediment samples were analyzed for total metal content, acid volutile sulphides (AVS) and simultaneously extracted metals (SEM). A high total metals content was determined (mainly Cu, Ni and Zn), which indicates that the sediment requires remediation. The AVS and SEM results show that in almost every profile, the molar concentration of metals is less than the molar concentration of sulphides, which suggests that in practice, the metals are not bioavailable. The high metals content of the sediment means that drudging of the canal will be necessary, during which, attention will have to be paid to avoid causing negative effects from the metals present in the sediment.