Historical sedimentary deposition and flux of PAHs, PCBs and DDTs in sediment cores from the western Adriatic Sea

Abstract

The sources and depositional history of polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds (OCs) over the last century were investigated in sediment cores from the North Adriatic Sea (Po River prodelta) and the South-Western Adriatic Margin (SWAM). Contaminant concentrations were higher in the Po River prodelta. ∑16PAHs ranged from 193 to 533 ng g−1, ∑5PCBs ranged from 0.9 to 5.2 ng g−1 and ∑DDTs (p,p′-DDD + p,p′-DDE) ranged from 0.1 to 2.5 ng g−1. In the SWAM, ∑PAHs ranged from 11 to 74 ng g−1 while ∑PCB and ∑DDT concentrations were close to the MQL. Accordingly, contaminant fluxes were much higher in the northern (mean values of 152 ± 31 ng cm2 y−1 and 0.70 ± 0.35 ng cm2 y−1 for PAHs and OCs, respectively) than in the southern Adriatic (2.62 ± 0.9 ng cm2 y−1 and 0.03 ± 0.02 ng cm2 y−1 for PAHs and OCs, respectively). The historical deposition of PAHs seemed to be influenced by the historical socioeconomic development and by changes in the composition of fossil fuel consumption (from petroleum derivatives to natural gas) in Italy from the end of the 19th century to the present. Similarly, vertical variations in DDT concentrations matched its historical use and consumption in Italy, which started around in the mid-late 1940s to fight typhus during the II World War. Contaminant concentrations detected in sediments does not seem to pose ecotoxicological risk for marine organisms in the Adriatic Sea.