Greenhouse gas emission from small wetlands in the göteborg area, sw sweden -

Abstract

Measurements of spatial variability of methane and carbon dioxide emissions from small lake mires in Göteborg area were done using a closed chamber technique during April- July in 1998. The investigated peatlands were of intermediate fen, poor fen, mixed carr and gently raised bog character. The mire gas was collected in 22-ml headspace bottles and then analysed in the laboratory by GC/MS and GC/FID techniques. The chromatographic methods used in this study were developed and optimised to suit the analyses of trace gases. The seasonal mean methane fluxes ranged from -31 to 295 mg CH4 ´ m-2 d-1. The largest emissions were associated with waterlogged communities of intermediate and poor fen. The consumption of atmospheric methane was found in the mixed carr community and the lagg area of the raised bog. The methane emissions showed an increasing trend during the sampling period. The seasonal carbon dioxide fluxes ranged between 7.4 and 18.7 g CO2 ´ m-2 d-1. The May carbon dioxide values were approximately two times larger compared to July's values. In generally, maximum methane fluxes for each point were corresponding to minimum carbon dioxide emissions. It was found that the soil temperatures and water table positions were the major factors controlling the emissions of methane and carbon dioxide. It was however difficult to determinate which factor was of largest importance. The quality of peat soils was found to be another important factor controlling the magnitude of methane production.