There are emissions of mercury to the atmosphere, soil and rivers of the Brazilian Amazon stem from many sources. Once in the atmosphere, the metal is oxidized and immediately deposited. In the water, the transformation to methylmercury takes place mostly by the action of microorganisms. The formation of methylmercury increases the dispersion and bioavailability of the element in the aquatic environment. Methylmercury can be assimilated by plankton and enters the food chain. The concentration of mercury increases further up in the trophic levels of the chain and reaches the highest values in carnivorous fishes like tucunare. Therefore, mercury emissions cause the contamination of natural resources and increase risks to the health of regular fish consumers. The objective of this work was to study the bioaccumulation of mercury in tucunares (Cichla sp.), top predators of the food chain. The fishes were collected at two locations representative of the Amazonian fluvial ecosystem, in the state of Pará, Brazil, in 1992 and 2001. One location is near a former informal gold mining area. The other is far from the mining area and is considered pristine. Average values of total mercury concentration and accumulation rates for four different collection groups were compared and discussed. Tucunares collected in 2001 presented higher mercury contents and accumulated mercury faster than tucunares collected in 1992 notwithstanding the decline of mining activities in this period. The aggravation of the mercury contamination with time not only in an area where informal gold mining was practiced but also far from this area is confirmed.Keywords: mercury; bioaccumulation; tucunares, Amazon.
Bioacumulação de Mercúrio em Tucunarés da Amazônia Brasileira(Cichla sp., Cichlidae, Perciformes)
RESUMOAs emissões de mercúrio para a atmosfera, solo e rios da Amazônia Brasileira provêm de diversas fontes. Uma vez na atmosfera, o metal é oxidado e se deposita imediatamente. Na água, a transformação para o metilmercúrio ocorre principalmente pela ação de VERA, Y. M; CARVALHO, R. J.; CASTILHOS, Z. C.; KURTZ, M. J. R. Mercury Bioaccumulation in the Brazilian Amazonian Tucunares (Cichla sp., Cichlidae, Perciformes). Ambi-Agua, Taubaté, v. 3, n. 2, p. 19-27, 2008 . (doi:10.4136/ambi-agua.49) microrganismos. A formação do metilmercúrio aumenta a dispersão e biodisponibilidade do elemento no ambiente aquático. O metilmercúrio pode ser assimilado pelo plâncton e entra na cadeia alimentar. A concentração do metal aumenta à medida que se ascende nos níveis tróficos da cadeia e atinge os valores mais elevados em peixes carnívoros como o tucunaré. Dessa forma, as emissões de mercúrio causam a contaminação dos recursos naturais e aumentam os riscos para a saúde dos consumidores habituais de pescado. O objetivo deste trabalho foi estudar a bioacumulação de mercúrio em tucunarés (Cichla sp), predadores de topo da cadeia alimentar. Os peixes foram coletados em dois locais representativos do ecosistema fluvial Amazônico, no estado do Pará, em 1992 e ...