Evaluation of bioavailability of trace metals through bioindicators in a urbanized estuarine system in southeast Brazil.

The mussel Perna perna is one of the most used bioindicators of coastal areas and the most economically exploited species in Brazil through mariculture. In the present study, P. perna was used to investigate metal pollution in the estuarine area of Vitória Bay. Four sampling sites were located along an estuarine branch of Vitória Bay and stations were sampled during three campaigns. Trace metals in the tissues of P. perna were evaluated as well as dissolved trace metals and other ancillary variables in the water column. Dissolved Cd, Pb, Cu, Ni, and Fe concentrations surpassed the tolerance limits stablished by legislation in all the sampling campaigns. P. perna exhibited concentrations in disagreement with the Brazilian legislation for Cr and As. A general trend of higher concentrations in outer stations was observed for most metals, what suggested the occurrence of flocculation process in the lower estuary, reducing the concentrations of dissolved elements and increasing their bioavailability for the biota through the particulate form. Cd was highlighted with elevated concentrations in dissolved fraction but not detected in P. perna, probably due to chlor-complex formation under influence of more saline waters. Al, Ba, Mn, Fe, Cu, Zn, Ni, Cr, Pb, and As were considered bioavailable, once they were accumulated in the mussels' tissues. Hazard index (HI) and target cancer risk (TCR) showed that the consumption of mussels from the study area offers health risk issues, being iron and arsenic the main contributors for the high indexes.

Human health risk assessment associated with the consumption of mussels (Perna perna) and oysters (Crassostrea rhizophorae) contaminated with metals and arsenic in the estuarine channel of Vitória Bay (ES), Southeast Brazil.

The estuarine channel of Vitória Bay was evaluated regarding bioaccumulation of metals (Al, Ba, Mn, Fe, Zn, Cu, Cr, Pb, Ni, Cd, Hg) and As in mollusks. Mussels from an aquaculture farm and transplanted into the estuary, whereas oysters were collected in situ in the same area. Concentrations of Al, Mn, Fe, Cr and As were higher in P. perna, whereas C. rhizophorae bioaccumulated more Ba, Zn and Cu. Arsenic concentrations in P. perna exceeded the limit of the Brazilian legislation in the outer estuary. Salinity seemed to influence metal uptake differently for each bivalve, with P. perna absorbing more metal at higher salinities and C. rhizophorae in areas of lower salinity. Hazard index (HI) >1 revealed risk for both bivalves for high level consumers. Target Cancer Risk (TCR) for As revealed threat for human health associated with the consumption of mussels and oysters from the study area.

Assessment of bioavailability and potential toxicity of Cu, Zn and Pb, a case study in Jurujuba Sound, Rio de Janeiro, Brazil.

Potential toxicity of sedimentary Cu, Zn and Pb were evaluated based on their fractionation at the inner part of Jurujuba, a small sound at the eastern margin of Guanabara Bay, Rio de Janeiro. Biogeochemical composition revealed an environment extremely enriched with anthropic organic matter and characterized as a detrital heterotrophic system. The fractionation analysis showed that Pb exhibited more affinity with the residual fraction followed by the amorphous Fe/Mn fraction. Cu and Zn were more expressive in the amorphous Fe/Mn fraction followed by the organic one and crystalline Fe/Mn fraction, respectively. According to Igeo index, sediments proved to be highly polluted by Zn and Cu and moderated polluted by Pb. Despite the actual contamination of Jurujuba sediments, the mobility of these elements seems to be limited since the most excessive concentrations were found in the less available fractions, depending on extreme physico-chemical variations to be released.