Trace metals enrichment and potential ecological risk in sediments of the Sepetiba Bay (Rio de Janeiro, SE Brazil)

The Sepetiba Bay (SB; SE Brazil) has been severely affected by growing of urbanization and industrial activity. This work aims to analyze the evolution of contamination by metals of sediments in SB. The results show a marked increasing trend in the concentrations of potentially toxic elements (PTEs), which is consistent with the rapid populational and industrial growth, mostly since 1970 CE. The remobilization and redistribution of sediments by currents have contributed to the dispersion of metals from the main source of pollutants to relatively distant regions. Moderately to strongly polluted sediments are also recorded in some sites in deeper sedimentary layers (namely in preindustrial periods), probably due to lithologic sources of the sediments. The concentrations of PTEs in SB are relatively high when compared with those found globally and in other Brazilian water bodies. Samples of high-resolution sediment cores confirmed that potential ecological risk to the coastal system is influenced not only through human actions but also by natural causes.

Automated summary

The Sepetiba Bay in Southeast Brazil has been heavily impacted by urbanization and industrial activity. This study examines the pollution levels of metals in sediments in the bay. The results indicate a significant increase in concentrations of potentially toxic elements, in line with rapid population and industrial growth since 1970. Currents have played a role in the dispersion of pollutants from the main source to distant areas. The sediments in deeper layers also show pollution, possibly from lithologic sources. The concentrations of potentially toxic elements in the bay are relatively high compared to global and other Brazilian water bodies. High-resolution sediment cores confirm that the coastal system's ecological risk is influenced by both human activities and natural causes.