Ba. Branfireun et al., Mercury cycling in boreal ecosystems: The long-term effect of acid rain constituents on peatland pore water methylmercury concentrations, GEOPHYS R L, 28(7), 2001, pp. 1227-1230
Sulphate-reducing bacteria have been identified as primary methylators of m
ercury (Hg) in the laboratory and in field investigations. However, no stud
ies have investigated the effect of long-term deposition of sulphate on met
hylmercury (MeHg) dynamics in peatlands, which are known to be significant
sources of MeHg to downstream waters in the boreal forest zone. As an ancil
lary experiment to a larger project investigating the effects of acid rain
constituents on peatland carbon dynamics, the influence of experimentally e
levated Na2SO4 and/or NH4NO3 deposition on peat pore water MeHg concentrati
ons was determined using a simple mesocosm experimental design. After three
years, additions of S in amounts equivalent to the 1980s dry and wet depos
ition in Southern Sweden resulted in peat pore water MeHg concentrations up
to six times above background levels. Elevated N loads had no effect on po
re water MeHg concentrations.