Mobility and Bioavailability of Metals in sediments of Skadar Lake - Montenegro

Abstract

Metals in sediments are present in different chemical forms, which mostly affect their ability to transfer in water and plants i.e. their bioavailability. The mobile part of metals is potentially toxic, thus for the evaluation of the bioavailability it is often enough to determine the metal content in the available and potentially available fraction of sediment. The aim of this study was to compare some methods of determination of mobile forms of heavy metals and to determine their share related to the pseudo-total metal content in the sediment from Skadar Lake, Montenegro. Mobile forms of Cu, Co, Cr, Mn, Ni, Pb, Zn, Sr and V were determined using: 0.1M NH4Cl (buffered to pH 9), 0.1M CaCl2 (pH 6), 0.1M CH3COONa (pH 9), 0.1M H2C2O4 (pH 2) and 0.1M EDTA (pH 6),. The largest amounts of Co (42.2 wt.%), Cr (11.4%) , Mn (59.9%), Ni (13.5%), Zn (41.0%) and V (42.2%) were extracted with oxalic acid and Cu (44.7 wt.%), Pb (49.3%), and Sr (61.2%) with EDTA. With NH4Cl, CaCl2 and CH3COONa small amounts of metals were extracted (except Sr), generally below 1%. Based on these results we can conclude that the metals in the sediments of Lake Skadar are found in a negligible amount in easily mobile, acid soluble and carbonate-related phase.