LAUSR

Northern peatlands in their natural state are sinks of carbon dioxide (CO2) but sources of methane (CH4). They are often nitrogen limited and can act as sinks for greenhouse gas (GHG) nitrous oxide (N2O). Peatlands have been used to treat wastewaters from different point sources. Continuous nutrient and pollutant load to a nutrient limited peatland ecosystem may change the microbial processes and lead to increased productivity, which together are likely to change the GHG emissions. We studied the effect of wastewater derived from metal mining on N2O and CH4 emissions on two treatment peatlands in northern boreal zone. The measured CH4 fluxes from the reference point without any wastewater load were in the range of those reported from northern pristine peatlands while emissions from treatment peatlands were greatly reduced, presumably as result of high sulfate concentration in the porewater. N2O emissions were small in the reference point, but up to 300 times higher in the treatment peatlands. Methane emissions increased with increasing total organic carbon concentration and decreased with increasing sulfate concentration in the surface water, respectively, while N2O emissions increased with increasing nitrate concentrations. The data indicate drastic changes in GHG fluxes and related biogeochemical processes in treatment peatlands as compared to the reference point.