Source, distribution and dispersion pattern characterization of heavy metals and pahs in sediments of the estuaries and continental shelf of the basque autonomous region (southeastern Bay of Biscay)

Resumen

Taking as a case study the Basque coastal area, and in order to delve into the knowledge of thesources and the distribution and dispersion patterns of contaminants in sediments, thefollowing objectives have been defined in the present Thesis: (i) to identify the relevantsources of heavy metals and PAHs; (ii) to assess the spatial distribution of these contaminants;(iii) to analyze the dispersion dynamics of riverine particulated Pb, under mean climatologicalconditions; and (iv) to assess the suitability of the used methodology and obtained results insupporting the assessment and management processes required under current Europeanmarine legislation.For that end, multivariate statistics, GIS-mapping techniques and numerical modelling toolshave been combined. This approach has permitted the identification of processes related tothe origin, distribution and dispersion of sedimentary contaminants at small- and large-spatialscales. At small-spatial scales, point contaminant sources are predominant. The small-spatialscale variability of contaminant distribution is determined by the proximity to these pointsources and by changes in hydromorphological conditions. At large-spatial scales, diffusesources show a primary importance: these relate to the geological composition of the basinsand factors associated with urban development. On the shelf, the prevailing hydrodynamic andsediment transport processes favour the stable redistribution of heavy metals and PAHs.The results obtained in this Thesis provide a complete viewpoint of the processes and activitiesinvolved in the origin, distribution and dispersion of contaminants. Therefore, they can beconsidered as being an interesting source of scientific knowledge under current Europeanmarine legislation (Water Framework Directive and Marine Strategy Framework Directive) andcan be used for environmental management purposes.