Changes in Cd and Zn distribution in sediments after closure of an electroplating industry, Sepetiba bay, Brazil

The spatiotemporal attenuation of Cd and Zn concentrations was assessed in sediments from Sepetiba Bay, which is a coastal system that has been historically impacted by industrial wastes. The evolution of contamination over the years shortly before and after cessation of electroplating industry activities, by the end of 1990's, was elucidated by reviewing the existing datasets for the whole bay area. Metal concentrations exceed Brazilian Sediment Quality Guidelines in most regions, corresponding to concentrations 3 to 4 orders of magnitude higher than background levels and Enrichment Factors reaching values significantly higher than 40 for both elements. In the second decade after electroplating industry closure, the levels of Cd and Zn lowered in most regions of the bay. However, an increase in the relative importance of diffuse sources can mislead the current and future identification of Cd and Zn input, bringing new challenges for environmental monitoring and management for Sepetiba bay. •Electroplating plant pollution attenuation was evidenced at decadal time scales.•Cd and Zn levels declined within one decade after electroplating activity end.•Highest levels persisted due to fluvial and electroplating by-products sources.•Enrichment factors indicate high environmental risk in the inner part of the bay