Changes of heavy metal and PCB contents in surficial sediments of the Barcelona harbour after the opening of a new entrance

Abstract

The Barcelona harbour is one of the biggest and most important in commercial and passenger traffic in the Mediterranean Sea. In 2003, construction works for the enlargement of the port were carried out with the opening of a new entrance for large boats in the northern area. Following the opening of this new mouth, the redistribution of heavy metals (Hg, Cd, Pb, Cu, Zn, Ni and Cr), As and polychlorinated biphenyls (PCBs) was investigated to discuss their origin and to evaluate the environmental implications. A previous study of the sediments provided a first picture of high levels of heavy metals and PCBs in the innermost harbour (Port Vell). Then, the opening of the northern mouth led to a remarkable decline in the contaminant concentrations and to an improvement of the sediment quality. During the period 2002–2005, the percentage of concentration decreases in Port Vell for Hg, Pb and PCB (from 20% to 34%), for Zn and Cd (from 10% to 15%) and for the remaining metals with values lesser than 10%. This general decline was probably due to a more efficient water flushing between the original and the new northern entrance. Concentrations of target contaminants were also compared against sediment quality guidelines to assess the ecotoxicological significance of sedimentary contaminants on the benthic communities.