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.

Sediment quality in a metal-contaminated tropical bay assessed with a multiple lines of evidence approach.

A sediment quality assessment was performed near to the main industrial source of metal contamination in Sepetiba Bay, Brazil, which represents one of the worst cases of trace metal contamination reported for coastal areas. Acute and chronic toxicity tests, benthic fauna community analysis and metal bioavailability evaluations were applied to identify risks to the benthic community. Significant amphipod mortality was observed close to the major pollution source and lower copepod fertility was observed for all stations. Equilibrium-partitioning and biotic-ligand models to predict pore water metal toxicity, which were based on acid-volatile sulfide (AVS) and organic carbon fraction (fOC) normalization approaches, suggested that metals are not likely to be available in sediment pore water. However, Cd, Pb and Zn concentrations were mainly (>50%) weakly bound to sediments, suggesting high potential bioavailability. Linking the chemical results with ecotoxicological responses, we observed that sediment-feeding organisms presented acute and chronic toxicities that were positively correlated to the metal concentrations in the sediments. Additionally, benthic fauna composition was dominated by tolerant species, revealing a trophic structure response to environmental contamination. These results reinforce the necessity of a multiple lines of evidence approach to establish sediment quality and to support environmental management decisions that are based on observed effects and potential extrapolation scenarios into the future.

Geochemical and ecotoxicological assessment for estuarine surface sediments from Southern Brazil.

Sediments from Guaratuba Bay (PR, Brazil), a marine protected area, were collected and evaluated for geochemistry and toxicity. High levels of P and acute toxicity were observed in some samples. Concentrations of Cu, Cd, Pb and Zn were relatively low; however, Cd levels eventually exceeded Threshold Effect Level. Toxicities were associated to nutrients and metals enrichment. Results suggest that impacts are incipient and occur only at specific sites, associated to multiple contamination sources. Despite sediments quality seems to range between good and fair, attention is required to land-use planning around Guaratuba Bay and controlling local pollution sources.