Ostra de mangue (Crassostrea rhizophorae) como biomonitor de poluição por mercúrio em quatro estuários cearenses

Abstract

Heavy metals are the manliest pollutants found in estuarine environments. Among the metals, mercury receives special attention due to their toxicity, posing risks to humans. Biological indicators have been used to assess the state of contamination by metals in these environments. This study aimed to use the mangrove oyster (Crassostrea rhizophorae) as biomonitor Hg in four estuaries of Ceará State at different levels of contamination. The analyzed material was digested in microwave (MARS XPRESS - CEM) and the quantification of Hg was carried out by atomic absorption spectrophotometry by cold vapor - CVAAS, model NIC RA-3 NIPON. The results showed higher concentrations of Hg in oysters in the estuary of the river Ceará (95 ± 14 ng.g-1 ) and the lowest in Pacoti (52 ± 3 ng.g-1 ). Despite being an rural river, the Jaguaribe estuary (69 ± 6 ng.g-1 ) had an average concentration of Hg larger than the Cocó, urban estuary (61 ± 7 ng.g-1 ). Comparing the data obtained in this study with previous studies on the same site it was observed a decrease of Hg concentrations in Cocó and Ceará estuaries and an increase in rural areas, Jaguaribe and Pacoti estuary. The values found in this study were lower than those found in the literature, however they are still represent values of contaminated areas