Concentrations of heavy metals in Sotalia fluviatilis (Cetacea: Delphinidae) off the coast of Ceara, northeast Brazil

摘要

Lead (Pb), cadmium (Cd) and mercury (Hg) concentrations on liver and kidney of Sotalia fluviatilis (Cetacea: Delphinidae) stranded in the coast of Ceara, Brazil, were studied from 1996 to 1999. Pb levels were usually lower than the detection limit (0.1 μg/ g). Concentrations of Cd were significantly higher in kidney than liver, averaging 0.8 μg/g. Mercury accumulation took place mainly in liver with an average concentration of 4.6 μg/g. Both metals were significantly higher in larger mature individuals, but differences between sexes were not significant. The detection of Cd, Hg and Pb in tissue samples of S. fluviatilis off the coast of Ceara indicated that heavy metals are locally available in the water, and bioaccumulation may be occurring through the food web. Contamination levels were not considered critical, but could be related to Ceara's growing industrial development. The associated risks of pollution outfalls may pose a threat to marine organisms in a near future, especially for top predators such as S. fluviatilis.