Search

[1] Methane fluxes were measured at five sites representing oligotrophic peatlands along a European transect. Five study plots were subjected to elevated CO2 concentration (560 ppm), and five plots to NH4NO3 (3 or 5 g N yr(-1)). The CH4 emissions from the control plots correlated in most cases with the soil temperatures. The depth of the water table, the pH, and the DOC, N and SO4 concentrations were only weakly correlated with the CH4 emissions. The elevated CO2 treatment gave nonsignificantly higher CH4 emissions at three sites and lower at two sites. The N treatment resulted in higher methane emissions at three sites (nonsignificant). At one site, the CH4 fluxes of the N-treatment plots were significantly lower than those of the control plots. These results were not in agreement with our hypotheses, nor with the results obtained in some earlier studies. However, the results are consistent with the results of the vegetation analyses, which showed no significant treatment effects on species relationships or biomass production.

Greenhouse impacts of different peat fuel utilisation chains were studied. A life cycle approach was used in order to cover all important emissions and sinks due to activities linked to the peat fuel production and utilisation. Radiative forcing was used to describe the greenhouse impact, and the results are given per one petajoule of energy produced. Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions and sinks were considered. Investigated peat production reserves were pristine peatland (fen), forestry-drained peatland, and cultivated (cropland) peatland. The considered phases of the peat utilisation chain included peat fuel production, storage, transport, combustion and the after-treatment of the cut-away peatland. After-treatment alternatives were afforestation and restoration. The greenhouse impact of a considered peat fuel chain was calculated by subtracting the emissions/sinks of a production reserve in a state of non-utilisation from the emissions/sinks of peat utilisation chain. According to the results, the most climate-friendly peat production chain is cultivated peatland-afforestation. Cultivated peatland has large greenhouse gas emissions and these emissions from the land area are ceased by the removal of the peat layer, when the area is utilised for peat fuel production. If forestrydrained peatland or pristine fen is used for peat fuel production, the greenhouse impacts of these chains are of the order of the greenhouse impact of the utilisation chain for coal. Improvement of peat production and combustion methods can be applied to decrease to some extent the greenhouse effect of peat energy.