EPA estimates 50 tons a year from US coal plants. [1]
Around 8.5% of global coal consumption is from the US [2], so a ballpark estimate would be 588 tons/year globally from coal. I would guess this estimate is a bit low as there are EPA standards to limit mercury emission by coal plants [3]. Top coal consumers like India and China are likely to have less mercury emission regulations, but I don't have a source for that. US coal varies in mercury content by up to 3x [1] so global mercury emissions are likely to be highly dependent on coal sources.
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EPA estimates 50 tons a year from US coal plants. [1] Around 8.5% of global coal consumption is from the US [2], so a ballpark estimate would be 588 tons/year globally from coal. I would guess this estimate is a bit low as there are EPA standards to limit mercury emission by coal plants [3]. Top coal consumers like India and China are likely to have less mercury emission regulations, but I don't have a source for that. US coal varies in mercury content by up to 3x [1] so global mercury emissions are likely to be highly dependent on coal sources.
[1] https://pubs.usgs.gov/fs/fs095-01/fs095-01.html#:~:text=EPA%....
[2] https://www.worldometers.info/coal/coal-consumption-by-count...
[3] https://www.epa.gov/mats/cleaner-power-plants