The impact of highway pollution on the coastal sea

The impact of motorway pollution on the coastal sea in the Bay of Koper (Gulf of Trieste, northern Adriatic) was studied by the analysis of polycyclic aromatic hydrocarbons (PAH) and heavy metals (Pb, Zn, Ni, Mn, Cu, Cr, Cd) in marine sediments, and selected benthic organisms, namely, the bivalve Mytilus galloprovincialis, the gastropod Patella coerulea and seagrass Cymodocea nodosa. The impact of motorway pollution was evident in higher contents of PAH and heavy metals in bivalves and gastropods collected in the mediolitoral because the contaminants are prevalently bound to particles and accumulated by organisms. The accumulation of pollutants in the sediments of the Bay of Koper is less significant due to the sedimentological properties (mostly coarse sediment) of the nearshore zone of the Bay, and advective transport of particles. The sedimentological properties also govern the distribution and preservation of PAH in the study area since the degradation of PAH is slower in pelitic sediments at the Bay entrance and in the central part of the Gulf of Trieste. These are also the principal sites of pollutant accumulation. The described contamination of benthic organisms was, however, not reflected on the benthic community level which does not show any sign of degradation and any difference from the apparently uncontaminated northern shoreline of the Bay.