Geochemical partitioning of heavy metals in sediments of three estuaries along the coast of Rio de Janeiro (Brazil)

Abstract

The geochemical partitioning of Cu, Cd, Cr and Pb was studied in sediments of three estuaries along the coast of Rio de Janeiro. The results show that, under contaminated conditions, the lithogeneous fraction of the total metal concentration decreases in importance, and mobile frac- tions dominate. Dilution with less contaminated marine sediments and the effect of salinity on metal behaviour could only be observed in the uncontaminated estuary. Under oxic conditions the reducible fraction is the more important sink for metals among the mobile phases. However, in the area with high organic sewage inputs, the oxidizable fraction can account for the greater fraction of total metal content. This latter result suggests a synergistic effect between organic pollution and metal contamination, since metals in oxidizable forms may be remobilized during mixture with oxic marine sediment.