We investigated the evasion of TGM (total gaseous mercury) from
experimental plots on a boreal peatland that had been exposed for 15 years to
different combinations of atmospheric sulfur (S) and nitrogen (N) deposition as well
as greenhouse treatments simulating climate change. Shaded dynamic flux chamber
measurements during the summer in 2009 showed emission of TGM to the
atmosphere from most of the treated plots (0.7 ± 0.94 ng m⁻² h⁻¹). However, TGM
exchange rates were significantly lower, occasionally indicating Hg uptake, on plots
subjected to S addition at rates of 20 kg ha⁻¹ year⁻¹. Enhanced nitrogen deposition
and greenhouse treatment had no significant effect on TGM fluxes. We hypothesize
that the lower Hg evasion from the sulfur-treated plots is related to either earlier Hg
evasion or Hg binding to S in organic matter, making Hg less susceptible to
volatilization and more prone to transport in runoff.