Bioaccumulation of total mercury and methyl mercury in soft tissue of the freshwater Carnivorous fish species

Department of Chemical Technology, University College of Science & Technology, University of Calcutta,

92, Acharya Prafulla Chandra Road, Kolkata-700 009, India

E-mail : mahuag@gmail.com, mgchemtech@caluniv.ac.in Fax 91-33-23519755

Manuscript received 20 April 2011, accepted 30 May 2011

Mercury (Hg) is one of the most malignant metals in the environment and one of the organic forms of Hg; methyl mercury (MeHg) is internationally recognized as toxic contaminants and elevated methyl mercury (MeHg) concentrations in fish is a world-wide environmental concern. This study investigated the presence of total mercury and organic mercury levels in various Carnivorous fish species captured from river. The results of mercury analysis in various specimens indicated that the some fish muscles tend to accumulate high levels of Hg and approximately 50-84% of that Hg is organic mercury. A. bengalensis bengalensis and W. attu possessed highest amount of organic mercury in their muscle tissues and contamination in M. armatus (0.45 ± 0.46), C. chitala (0.25 ± 0.18), R. rita (0.34 ± 0.15), L. calcarijer (0.25 ± 0.02) and O. pabda (0.26 ± 0.04) were also above the 0.25 µg Hg/g of wet weight, the limit set by PFA with the maximum level for consumption of fish exposed to MeHg. Though in P. pangasius (0.12 ± 0.16), B. bagarius (0.12 ± 0.01) and C. garua (0.1 ± 0.01), concentration was below the recommended level but in M. aor (0.23 ± 0.1) it was threatening. Interestingly, a low concentration of Hg was found in post-monsoon samples of all the species.