Mass spectrometric monitoring of gas dynamics in peat monoliths: effects of temperature and diurnal cycles on emissions

Membrane inlet mass spectrometry was used to monitor dissolved gas concentrations and gas exchange rates of CO2, CH4 and O2 in peat cores from three very different locations in the Northern Hemisphere: Kopparås Mire (Sweden), Hestur Site (Iceland), and Ellergower Moss (Scotland). With an increase of temperature gas solubilities are reduced, and due to additionally increased microbial activities higher gas emission rates for both CO2 and CH4 were observed. Experimental alterations of temperature and photosynthetically active radiation (PAR) also drastically effect daytime carbon dioxide emission rates as a result of changes in microbial and plant physiology. The impact of ebullition on gas emission rates was indicated by continuous measurements of gas concentrations in the headspace of Icelandic and Swedish cores using two different experimental setups. For methane, up to of the total emission from cores from both sites is released by ebullition. Total gas emission rate measurements in this study were similar for both experimental setups, and revealed gas effluxes comparable with field measurements for Scottish and Icelandic peat.