Stable isotopes of mercury, carbon, and nitrogen reveal fish mercury sources across Korean seas: Implications for marine biomonitoring

초록

Mercury (Hg) exposure through fish consumption is a major public health concern. While Hg concentrations in freshwater fish are driven by the degree and type of watershed Hg inputs followed by sediment methylation, the key factors controlling fish Hg concentrations in marine environments remain unclear. To address this knowledge gap, we aimed to identify the relative importance of environmental Hg sources, biogeochemical processes, and ecological characteristics of marine fish. We analyzed 51 individuals of 27 fish species from three seas (East Sea, Yellow Sea, South Sea) surrounding South Korea and found that fish from the East Sea had two-fold higher Hg concentrations than fish from the more industrialized Yellow Sea and South Sea. This challenges the long-standing assumption that the extent of anthropogenic Hg input determines fish Hg concentrations. Hg stable isotopes revealed atmospheric deposition as the dominant source to the East Sea and South Sea fish, while riverine and industrial discharge were the main sources to the Yellow Sea fish. In the East Sea, trophic characteristics exerted a greater influence than regional Hg sources and biogeochemical processes by facilitating Hg biomagnification. Our findings underscore the need for site-specific Hg biomonitoring adapted to an ecosystem, which is particularly relevant for nations with high seafood dependency. Copyright © 2026. Published by Elsevier Ltd.

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