RESUMO
Patagonian salt marshes are not affected by pollution, but historical mining wastes are a continuous source of metals to salt marsh in San Antonio Bay. The present study evaluated the concentration of metals in sediments and used the halophyte Spartina spp. and the crab N. granulata as biomonitors. The levels of metals in sediment and organisms in SAB remained at levels corresponding to a slight enrichment or contamination. The highest levels corresponded to innermost sites of the Encerrado channel and close to the mining wastes. Spartina is a phytostabilizer so its aboveground tissues do not reflect the concentrations in the sediment; although, it retains the metals in its belowground tissues and in the rhizosediment. N. granulata showed to be a useful biomonitor for Pb, but not for the other metals.
Assuntos
Monitoramento Ambiental , Metais Pesados/análise , Áreas Alagadas , Animais , Argentina , Braquiúros/química , Sedimentos Geológicos/análise , Masculino , Metais/análise , Mineração , Poaceae/químicaRESUMO
The San Antonio Bay is a protected natural coastal area of Argentina that has been exposed to mining wastes over the last three decades. Iron and trace metals of potential concern to biota and human health (Cd, Pb, Cu, and Zn) were investigated in the sediments from the bay and in the soils of the Pile (mining wastes). Concentrations of Cd (45 mg kg-1), Pb (42,853 mg kg-1), Cu (24,505 mg kg-1), and Zn (28,686 mg kg-1) in the soils Pile exceeded guidelines for agricultural, residential, and industrial land uses. Risk assessment due to exposure to contaminated soils (Pile) was performed. Hazard quotients were superior to non-risk (HQ >1) for all trace metals, while accumulative hazard quotient index indicated a high risk for children (HI = 93) and moderate for adults (HI = 9). In the bay, sediments closest to the Pile (mudflat and salt marsh) exceeded sediment quality guidelines for protection of biota. Results of different acid extraction methods suggest that most of the pseudototal content was potentially mobile. Principal component analysis indicated that the sites near the Pile (Encerrado channel) were more polluted than the distal ones. Tissues of Spartina spp. located within Encerrado channel showed the highest metal levels among all studied sites. These results show that the problem still persists and the mining wastes are the sources of the pollution. Furthermore, the Encerrado channel is a highly impacted area, as it is shown by their metal enriched sediments.