Evolution of Chemical Pollution in Catalan Coastal Sediments

Abstract

In 2000 and from 2006 to 2011, a monitoring program was followed along the Catalan inner shelf, using homogeneous analytical methods and sampling strategies and focusing on the main sites of river sediment accumulation at present. Adjacent areas that are potentially vulnerable to pollution were also selected. Trace metals and organic pollutants were analyzed in surface sediment samples. Mean concentrations in each area show a distribution of organic and inorganic pollutants along the Catalan inner continental shelf. The highest concentrations are located on and around the coast of Barcelona city for most pollutants and locally on the coast of Tarragona city and the Ebre Delta for some of them. The concentrations tend to decrease gradually southward and sharply northward of Barcelona. The trace metal that shows the highest anomalies is Hg (max. enrichment factor, 34), whereas Cd, Zn, Cr, Pb, and Cu show more moderate anomalies. Sediment polycyclic aromatic hydrocarbons, 4-nonylphenols (metabolites of nonylphenol polyethoxylated, nonionic surfactant), polybrominated diphenyl ethers, polychlorinated biphenyls, and dichlorodiphenyltrichloroethane are also significant. The time evolution of most trace metals shows a decreasing trend mainly between 2000 and 2006, whereas between 2006 and 2011 trends of trace metals and organic pollutants are not clear, as some of them increased and others decreased and many of them peaked in 2007 and 2009. The greatest decreases in trace metals were in the most polluted areas.