Three decades of Cd and Zn contamination in Sepetiba Bay, SE Brazil: Evidence from the mangrove oyster Crassostraea rhizophorae

摘要

The past 30 years have witnessed drastic changes in heavy metal pollution sources to the Brazilian environment, mostly due to the reduction of point source emissions as a result of strengthening control policies and changing indus- trial technology. However, little has been achieved in controlling non-point source emissions, and in many areas pollution has increased rather than decreased. In addition, changes in land use have affected heavy metal sinks and remobilized large amounts of pollutants even though many years have passed since the closure of the original sources. In Sepetiba Bay, SE Brazil, emission control policies have resulted in a decrease of about 55% and 13% of the Cd and Zn annual emissions to soils and waters, respectively (Lacerda et al., 2004; Molisani et al., 2004).