Heavy metal distribution, availability and fate in Sepetiba Bay, S.E. Brazil

Abstract

The total flux, distribution and fate of Cu, Cr, Cd, Zn, Mn and Pb were studied in Sepetiba Bay, Rio de Janeiro, SE Brazil. Metal contamination in the bay is of the same order of magnitude as historically contaminated areas of Europe and North America, inspite of the recent (15–20 years) contamination of the area.

The estimated metal fluxes to the bay in tons per year are: Cu, 2.7; Cr, 10.9; Cd, 0.9; Zn, 11.5; Mn, 20.4; and Pb, 4.5. For most metals, transport to the bay is mainly by suspended particulate matter; for Cd and Cr 90 and 47% of the total flux was in dissolved forms. Most metals transported by suspended particulate matter were in weakly bound forms.

Analysis of bottom sediments showed two groups of metals in relation to their distribution and source in the bay. Manganese and Cu showed higher concentration along the southern parts of the bay, showing no correlation with the other metals, and probably being derived from natural sources. The other metals were present at higher concentrations along the depositional area of fluvial sediments, at the northern part of the bay, and are derived from industrial and urban sources.