Concentration and toxicity assessment of contaminants in sediments of the Itaipu–Piratininga lagoonal system, Southeastern Brazil

Abstract

The Itaipu–Piratiningalagoon system, which is located in Niterói City, Southeastern Brazil, has suffered significant environmental pressures due to its growing urbanization. Some of the compounds discharged in this waterbody, even at low concentrations, can have an impact on the aquatic biota. The main aim of the present study was to evaluate the quality of sediments found in the lagoon system. In total, 39 contaminants were analyzed (metals, polycyclic aromatic hydrocarbons, pesticides, and polychlorinated biphenyls) and acute toxicity was assessed through the luminescence of bacterium Vibrio fischeri (Microtox®). Based on results, the sediments collected presented concentrations below the detection limit rates set for almost all the assessed compounds, except for some metals. In comparison to similar studies and baselines found in the literature, the concentrations observed in this study are higher for Cu and Zn and lower for Pb and Ni. These same patterns were observed in comparison to national and international regulatory guidelines. The toxicity analysis, using bacterium V. fischeri, for samples collected at the 10 sites showed that only one of these sites recorded intense toxic activity. The Hormesis effect was observed in almost all sites in both sampling campaigns. Sampling sites located closer to the mouths of the larger tributaries and of Camboatá channel showed significant changes in the quality of their sediments. The present study brings contributions to the knowledge about a significant range of contaminants and physicochemical characteristics of sediments collected in Itaipu and Piratininga lagoons.