Mercury speciation and selenium in toothed-whale muscles
- National Institute for Minamata Disease, Hama 4058-18, Minamata, Kumamoto 867-0008 (Japan)
- Ehime University, Bunkyo 2-5, Matsuyama 790-8755 (Japan)
- Tohoku National Fisheries Research Institute, 25-259 Shimomekurakubo, Aomori 031-0841 (Japan)
- Institute of Cetacean Research, 4-5 Toyomi, Tokyo 104-0055 (Japan)
- Akita University School of Medicine, Hondo 1-1-1, Akita 010-8543 (Japan)
- University of Ottawa, Marie-Curie, Ottawa, ON, Canada KIN 6N5 (Canada)
- School of Medicine, IISPV, Universitat “Rovira i Virgili”, Reus (Spain)
Mercury accumulates at high levels in marine mammal tissues. However, its speciation is poorly understood. The main goal of this investigation was to establish the relationships among mercury species and selenium (Se) concentrations in toothed-whale muscles at different mercury levels. The concentrations of total mercury (T-Hg), methylmercury (MeHg), inorganic mercury (I-Hg) and Se were determined in the muscles of four toothed-whale species: bottlenose dolphins (n=31), Risso's dolphins (n=30), striped dolphins (n=29), and short-finned pilot whales (n=30). In each species, the MeHg concentration increased with increasing T-Hg concentration, tending to reach a plateau. In contrast, the proportion of MeHg in T-Hg decreased from 90–100% to 20–40%. The levels of T-Hg and Se showed strong positive correlations. Se/I-Hg molar ratios rapidly decreased with the increase of I-Hg and reached almost 1 in all species. These results suggested that the demethylated MeHg immediately formed Se/I-Hg equimolar complex of mercury selenide (HgSe) in their muscles. In addition, an X-ray absorption fine structure analysis (XAFS) of a bottlenose dolphin muscle confirmed that the dominant chemical form of the Se/I-Hg equimolar complex was HgSe. HgSe was mainly localized in cells near the endomysium using electron probe microanalysis (EPMA). These results suggested that the demethylated MeHg finally deposits within muscle cells of bottlenose dolphin as an inert HgSe. - Highlights: • T-Hg, MeHg, I-Hg and Se were determined in the muscles of four toothed-whales. • MeHg increased with increasing T-Hg and tended to reach a plateau in all species. • Se/I-Hg molar ratios rapidly decreased with increase of I-Hg and reached almost 1. • XAFS of bottlenose dolphin muscle confirmed that HgSe was dominant chemical form. • EPMA of bottlenose dolphin muscle showed that HgSe deposited in muscle cells.
- OSTI ID:
- 22687708
- Journal Information:
- Environmental Research, Vol. 143, Issue Part A; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0013-9351
- Country of Publication:
- United States
- Language:
- English
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