Comparação de metodologias de digestão de sedimentos marinhos para caracterização da geoquímica de metais-traço na plataforma continental nordeste oriental brasileira

Abstract

This study compares total and partial sediment digestion procedures on the interpretation of metal geochemistry in sediments (<1mm fraction) from the Ceará continental shelf. Al, Cu, Fe, Mn, Ni, Pb, V, Ba, Cr and Zn concentrations were determined by flame atomic absorption spectrophotometry. Cluster analysis showed two distinct groups of geochemical supports controlling the 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 marine carbonatic deposition Ni, Pb, Ba, Cu and organic matter content. Despite the differences between the absolute metal concentrations found by both digestion procedures, there was no distinction on the metal geochemistry characterization for these predominantly carbonatic marine sediments. This result indicates that the partial sediment digestion technique generates a similar geochemical characterization to the total digestion but is less time consuming and also reduces the discard of highly reactive laboratorial effluent.