Gauci, Vincent; Dise, Nancy and Blake, Stephen
Long-term suppression of wetland methane flux following a pulse of simulated acid rain.
Geophysical Research Letters, 32(L12804)
Wetlands are a potent source of the radiatively important gas methane (CH4). Recent findings have demonstrated that sulfate (SO4 2−) deposition via acid rain suppresses CH4 emissions by stimulating competitive exclusion of methanogens by sulfate-reducing microbial populations. Here we report data from a field experiment showing that a finite pulse of simulated acid rain SO4 2− deposition, as would be expected from a large Icelandic volcanic eruption, continues to suppress CH4 emissions from wetlands long after the pollution event has ceased. Our analysis of the stoichiometries suggests that 5 years is a minimum CH4 emission recovery period, with 10 years being a reasonable upper limit. Our findings highlight the long-term impact of acid rain on biospheric output of CH4 which, for discrete polluting events such as volcanic eruptions, outlives the relatively short-term SO4 2− aerosol radiative cooling effect.
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