Mercury distribution in sediments of a sub-trpical coastal lagoon, Sepetiba Bay, SE Brazil

Abstract

The distribution of Hg accumulated in sediments of Sepetiba Bay (Rio de Janeiro, Brazil) and its possible associations with sediment geochemical properties (iron, organic carbon, nitrogen, sulphur concentrations and organic matter content) were investigated. The spatial distribution of the variables considered in this study is predominantly determined by the pattern of water circulation, sediment transport along the eastern shore as well as natural and anthropogenic sources. The most important mercury source for the bay is the input from the main rivers, and their mouths are the most favourable sites for mercury accumulation. Sediment composition in this bay is strongly influenced by fluvial inputs of mercury, organic matter and fine-grained sediments, suggesting the partitioning of the bay into two regions; one receiving a strong influence from the rivers and the other mainly influenced by the sea.