sediment quality assessment of two industrialized areas of spain

pollution deriving from trace elements (cd, cu, ni, pb, zn, hg, as and cr) in sediment samples(collected in 2009), belonging to rivers located in catalonia and the basque country (spain), was assessedaccording to sediment quality guidelines. sediment samples were ranked in terms of a pollution index thattakes into account the presence of multiple pollutants such as trace elements. while only about 10% ofsamples located in rivers of catalonia showed significant potential toxicity related to trace elements, about53% of samples located in rivers of the basque country showed several potential toxicity issues related tothese pollutants. extremely high trace element concentrations were measured in some samples from this latter region, constituting a clear potential risk to the benthic fauna. the use of artificial neural networks (anns) such as self-organizing map (som) to classify sites according to their similar quality was found to be a reliable tool that can be incorporated in sediment quality assessments that include large datasets.