School of Environment, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
National Research Center for Environmental Analysis and Measurement, Beijing 100029, China.
Sci Total Environ. 2024 Feb 20;912:169557. doi: 10.1016/j.scitotenv.2023.169557. Epub 2023 Dec 21.
To elucidate the potential risks of the toxic pollutant mercury (Hg) in polar waters, the study of accumulated Hg in fish is compelling for understanding the cycling and fate of Hg on a regional scale in Antarctica. Herein, the Hg isotopic compositions of Antarctic cod Notothenia coriiceps were assessed in skeletal muscle, liver, and heart tissues to distinguish the differences in Hg accumulation in isolated coastal environments of the eastern (Chinese Zhongshan Station, ZSS) and the antipode western Antarctica (Chinese Great Wall Station, GWS), which are separated by over 4000 km. Differences in odd mass-independent isotope fractionation (odd-MIF) and mass-dependent fractionation (MDF) across fish tissues were reflection of the specific accumulation of methylmercury (MeHg) and inorganic Hg (iHg) with different isotopic fingerprints. Internal metabolism including hepatic detoxification and processes related to heart may also contribute to MDF. Regional heterogeneity in iHg end-members further provided evidence that bioaccumulated Hg origins can be largely influenced by polar water circumstances and foraging behavior. Sea ice was hypothesized to play critical roles in both the release of Hg with negative odd-MIF derived from photoreduction of Hg on its surface and the impediment of photochemical transformation of Hg in water layers. Overall, the multitissue isotopic compositions in local fish species and prime drivers of the heterogeneous Hg cycling and bioaccumulation patterns presented here enable a comprehensive understanding of Hg biogeochemical cycling in polar coastal waters.
为了阐明极地水中有毒污染物汞（Hg）的潜在风险，研究鱼类中积累的 Hg 对于了解南极洲区域尺度上 Hg 的循环和归宿至关重要。本研究评估了南极鳕鱼（Notothenia coriiceps）肌肉、肝脏和心脏组织中的 Hg 同位素组成，以区分东部分离沿海环境（中国中山站，ZSS）和西部分离沿海环境（中国长城站，GWS）中 Hg 积累的差异，这两个站点之间相隔 4000 多公里。鱼类组织中奇数质量非依赖性同位素分馏（odd-MIF）和质量依赖分馏（MDF）的差异反映了具有不同同位素指纹的甲基汞（MeHg）和无机汞（iHg）的特定积累。包括肝脏解毒和与心脏相关的过程在内的内部代谢也可能导致 MDF。iHg 端元的区域异质性进一步提供了证据，表明生物累积 Hg 的来源在很大程度上受到极地水条件和觅食行为的影响。海冰被假设在 Hg 的释放中起着关键作用，Hg 是通过其表面光还原产生的具有负奇数-MIF，同时还阻碍了水层中 Hg 的光化学转化。总的来说，本研究中本地鱼类物种的多组织同位素组成以及异质 Hg 循环和生物累积模式的主要驱动因素，使我们能够全面了解极地沿海水域中 Hg 的生物地球化学循环。
