Metal contamination recorded in the sediment of the semi-closed Bakar Bay (Croatia)

This study presents information on the sediment metal levels in Bakar Bay, with the main goal to evaluate recent, as well as historical, anthropogenic influence. Sediment profiles at 7 sampling points throughout the bay were taken. Chemical contents in bulk sediments were obtained using ICP, ICP-MS and AAS methodologies and 20 of the most significant elements are discussed. Concentrations of selected elements were evaluated by factor statistical analyses to identify their source. Also, metal enrichment factor and geoaccumulation indexes were calculated and spatial distribution maps for three sediment layers were constructed. Measured metal concentrations in the sediment were compared with concentrations in other sediments from the Adriatic Sea. In addition, a set of sediment quality guidelines was applied in order to predict the probability of adverse biological effects on the benthic community. Factor analysis clearly demonstrated the segregation between metals of natural origins, soil and bedrock weathering (Li, Al, Cr, Sc), from two anthropogenic sources originating at the city of Bakar and bulk cargo terminal (Hg, Pb, Zn, Ag, Sn, Fe). Mercury (max 0.65 μg g-1) was found to be the element of greatest contamination, followed by lead (max 71.5 μg g-1), copper (89.3 μg g-1) and zinc (156 μg g-1). However, this study demonstrates that Bakar Bay is considerably less polluted with toxic metals than was initially believed