Study on quantitative speciation, by BCR method, of Zinc content from river sediments

Abstract

An unwanted consequence of human activity and of uncontrolled industrialization is the environment contamination with a lot of pollutants, among them heavy metal anthropogenic pollution having some most serious consequences. A reliable estimation of pollution level is made by studying heavy metal concentrations in the sediments. In our study the zinc content of the water and river sediments has been investigated, in an area polluted by mining activities, to provide information on the mobility and availability of this element. Sediment and water samples have been collected from significant sites in a former mining area in which with some sterile pits, which represent a major environmental hazard. The zinc mobility and bio-availability in the environment was investigated by the three-step sequential extraction procedure, a protocol proposed by the Standards, Measurements and Testing programme (SM & T–formerly BCR) of the European Union. The BCR sequential extraction scheme has the advantage that there are reference materials available with certified and indicative values for the concentrations of selected elements in the particular extraction steps. The BCR procedure enables fractionalization of metal content into the following fractions: • EASILY MOBILIZABLE FRACTION: This fraction contains the specifically bound, surface occluded species (sometimes also CaCO3 bound species and metallo-organic complexes with low bonding forces). • ORGANICALLY BOUND FRACTION • Mn-Fe-and Al-OXIDE BOUND FRACTION • RESIDUAL FRACTION: This fraction mainly contains crystalline-bound trace metals and is most commonly dissolved with high concentrated acids and special digestion procedures. Combination of data from sequential extraction procedures and normalization approaches provides a good basis to estimate the proportions of the easily and sparingly soluble metal fractions in the samples investigated and to identify the anthropogenic input of metals into the environment.