Bivalves Residue Analysis for the Assessment of Coastal Pollution in the Ebro Delta (NW Mediterranean)

An analytical approach is described for bioaccumulation and ecotoxicology assessment studies of organophosphorous pesticides (OPs), organochlorine compounds (OCls) and polycyclic aromatic hydrocarbons (PAHs) in bivalves cultured in the Ebro Delta. Species exhibiting a wide range of lipid contents, namely Mytilus galloprovincialis, Ostrea edulis, Crassostrea gigas and Ruditapes decussata were selected. Analyses of OPs were performed by gas chromatography (GC) with nitrogen-phosphorus detection (NPD), OCls were determined by GC with electron capture detection (ECD) and total PAHs using a flow injection system (FIS) with fluorescence detection. Residue analyses indicated differences among species, that were reduced when concentrations were normalized to lipid content. A seasonal fluctuation of pollutants was also observed that was related to the biological cycle of the organisms and to the management of the waters in the rice crop fields of the delta. Toxicity thresholds for bivalves were not reached; nevertheless, more sensitive species such as crustaceans could be potentially affected. Toxicological implications to humans might be of concern during field treatments with pesticides.