Mercury Bioaccumulation in the Brazilian Amazonian Tucunares (Cichla sp., Cichlidae, Perciformes)

  • Ysrael Marrero Vera PUC-Rio
  • Roberto José Carvalho PUC-Rio
  • Zuleica Carmen Castilhos CETEM
  • Maria Josefina Reyna Kurtz Scitech Environmental Science And Technology Ltda.
Keywords: mercury, bioaccumulation, tucunares, Amazon


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.

Author Biography

Roberto José Carvalho, PUC-Rio
Roberto José de Carvalho possui graduação em Engenharia Metalúrgica pela Pontifícia Universidade Católica do Rio de Janeiro (1975), mestrado em Engenharia Metalúrgica, área de concentração Metalurgia Extrativa, pela Pontifícia Universidade Católica do Rio de Janeiro (1978) e doutorado em Engenharia Metalúrgica, área de concentração Metalurgia Extrativa, pela University of British Columbia, Canadá, (1986). Atualmente é professor assistente da Pontifícia Universidade Católica do Rio de Janeiro. Tem experiência na área de Engenharia de Materiais e Metalúrgica, com ênfase em pirometalurgia e tecnologia ambiental, atuando principalmente nos seguintes temas: modelagem matemática e física, cinética, fenômenos de transporte e fluidodinâmica.