Geoquímica do Registo Sedimentar na Plataforma Portuguesa – Variações Espaciais e Temporais (original) (raw)

Three sediment cores were collected at the muddy deposits extending along the Portuguese shelf adjacent to Douro, Tagus and Guadiana estuaries, to assess the influence of these large Iberian rivers on the coastal marine environment. The elemental composition (major, minor and trace elements) was determined in selected fractions of the sampled cores, by energy-dispersive X-ray fluorescence spectrometry. The geochronological framework was established using the radionuclides 210Pb, 137Cs and 14C dating. The downcore variation profiles on the lithogenic, biogenic and anthropogenic elements were compared aiming at the identification of particular specificities associated to each drainage basin, and on the evaluation on the sediments sources during the Holocene. Temporal evolutional patterns on the heavy metal anthropogenic contamination were estimated for each of the drainage basins, as well as their relation with different human activities (e.g. domestic effluents, mining exploitation, ...