A coupled atmosphere-land-ocean model is developed with latest advances in Hg cycling
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The model indicates 40% larger total atmospheric emissions and land as a major sink
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More aggressive emissions control is required to reduce environmental Hg levels
Science for society
Mercury is a toxic metal that mainly affects human health through seafood consumption. The Minamata Convention on Mercury, an international agreement, aims to protect human health by reducing mercury emissions. However, the mercury in our environment is not only from current anthropogenic sources but also from re-emissions from land and ocean that have accumulated historical emissions. To effectively reduce environmental mercury levels, it is crucial to have a complete understanding of the global mercury budget.
In our study, we integrated the latest advances in atmospheric mercury redox chemistry, vegetation uptake, seawater sources, and riverine discharges through use of a coupled air-land-sea model. Our findings indicate 40% higher total mercury emission than previously estimated, mainly because of higher ocean re-emissions. This highlights the need for more aggressive emission reduction efforts to achieve the goal set by the Minamata Convention on Mercury.
Summary
The effectiveness of reducing the environmental level of mercury (Hg) by controlling anthropogenic emissions depends on the magnitude of re-emissions from the land and ocean, which requires a comprehensive understanding of its global biogeochemical cycle. Recent advances in atmospheric Hg redox chemistry, vegetation uptake, seawater Hg sources, and riverine discharges greatly challenge our understanding of the global Hg cycle, but the overall effects remain understudied. Here, we develop a new coupled atmosphere-land-ocean model and find potentially 40% higher total atmospheric Hg emissions than previously recognized primarily because of higher re-emissions from the ocean. Our results suggest a likely smaller sensitivity of environmental Hg levels to anthropogenic emission changes, stressing that potentially more aggressive emission control is required to decrease Hg levels.