Mercury (Hg) contamination of oceans is rapidly increasing, however Hg bioaccumulation in pinnipeds has been understudied. Here, we report for the first time Hg concentration in liver tissues of South American fur seals (Arctocephalus australis) in South and Southeast Brazil. Hg concentration was determined in twenty-five fur seals’ specimens found stranded along the coast of the Southwestern Atlantic Ocean. Samples were digested using the microwave technique and quantified by cold vapor generation atomic fluorescence spectrometry technique. The average Hg concentration was 6.37 mg kg-1 (wet weight), with a minimum concentration of 0.09 mg kg-1 and the highest concentration of 15.58 mg kg-1. No correlation between biological variables (sex, total length and weight) and Hg concentration in A. australis liver were found. The results presented here are of great importance to establish baselines for future evaluations of Hg contamination in marine mammals and the effects of this environmental problem in animal health.

This study compares the techniques cold vapour atomic fluorescence spectrometry (CV-AFS) and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of Hg in biological samples (hepatic tissue from marine tetrapods). Acid digestions were performed for the samples and aliquots of them were analysed by ICP-MS and CV-AFS. To minimize the Hg memory effect in its determination by ICP-MS, gold (200 µg L-1 in 5% v v-1 HCl) was added to the sample digests. The detection limits were 0.02 mg kg-1 for ICP-MS and 0.01 mg kg-1 for CV-AFS. Accuracy was assessed by the calculation of the recovery obtained from TORT-3 (lobster hepatopancreas) certified reference material analysis. Accurate results were obtained for both CV-AFS and ICP-MS. The comparison of the results obtained for hepatic tissue with and without lyophilization showed a significant difference among them (at 95% of confidence level), evidencing losses of Hg in the lyophilization process.