Temporal trend of heavy metal content in Guanabara Bay (Brazil) sediments - Five years of study.

The Guanabara Bay is a typical example the lagoon environment has suffered a heavy impact of industrial and urban pollution which caused the concentrations of heavy metals, eutrophicating substances, and organic pollutants to attain typical levels of very contaminated harbour areas. In the present study evaluated the variability heavy metals content in two monitoring campaign in Guanabara Bay during July 2003 and January 2007. The accumulation of heavy metals in the bottom sediments depends not only on the distribution of the various fluvial inputs, but also on the chemical interaction between metals and the constituents of sediments. Pollutants associated with sinking sediment particles become bound to inorganic or organic matrices by adsorption processes. The GEOCHEMICAL SPECIATION OF HEAVY METALS by sequential extraction procedure proposed by Chester R. et al., 1967 and Tessier et al., 1979; modified by Sager M., 1989; Rubio R. et al., 1993 and Perin G. et al., 1997) was applied in this work. The content of heavy metal (total and geochemical speciation) are determinate by VARIAN SpectrAA-10 (Flame Atomic Absorption Spectrometry) and VARIAN SpectrAA-250 Plus (Graphite Tube Atomizer). The results of our study demonstrated that the heavy metals content in sediments of Guanabara Bay in 2003, is highest in the north-western, above the Isla do Governador. These results have been confirmed by 2007 analysis. Considering either total metals data (2003) either geochemical speciation of metals data (2007), the area with the lowest metal values results the southern, in proximity of Atlantic Ocean inlet, influenced by the ingression of ocean salt water.