Comparação de metodologias para caracterização da geoquímica de metais-traço em sedimentos da plataforma continental do Ceará / 2007

Abstract

Aiming to verify the influence of leachi ng procedures total or partial sediment digestion techniques on the interpretation of trace metal geochemical partitioning in sedimentary environments, a comparison of methodologies were carried out on sediments (<1mm fraction) collected along Ceará’s continental shelf. Concentrations of Al, Cu, Fe, Mn, Ni, Pb, V, Ti, Ba, Cr and Zn were determined by flame atomic absorption spectrophotometry. Cluster analysis showed two distinct groups of geochemical support controlling depositional patterns. The first one was composed by metals of continental origin: Al, Fe, Mn, Cr and Zn. The second group was formed by metals associated to mari ne carbonatic deposition Ni, Pb, Ba, Cu and organic matter content. Despite the differences between the absolute metal concentrations found by both leaching procedures, there was no distinction on the metal geochemical characterization for predominantly carbonatic marine sediments. This result indicates that the partial sediment digestion technique generates an equivalent geochemical characterization but is less time consuming and also reduces the discard of highly reactive laboratorial effluent. Besides, an evaluation of Al and Ti as concentration no rmalizers was carried out inan adjacent area showing that the continental and/or anthropogenic metal source was distinguishable into two groups.