Methanogenesis and CO 2 exchange in an ombrotrophic peat bog

• Published in: Atmospheric environment (1994) Vol. 32; no. 19; pp. 3229 - 3238
• Main Authors: Lloyd, David, Thomas, Katie L, Benstead, Julie, Davies, Kevin L, Lloyd, Siôn H, Arah, Jonathan R.M, Stephen, Karl D
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1998
• Subjects: aerenchyma; circadian rhythms; gas exchange; Methane; plant-microbe interactions; Methane; plant-microbe interactions; aerenchyma; gas exchange; circadian rhythms
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/S1352-2310(97)00481-0

Methanogenesis was studied in water-saturated peat cores from hollows in Ellergower Moss, New Galloway, Scotland. The concentration of CH 4, increased with depth from 0.8 μM at the surface to reach a plateau of 500 μM at 14 cm; at this depth CO 2 concentrations often reached 10 fold those of CH 4. O 2 decreased from near air saturation to less than 10 nM at 6 cm depth. Argon transport from the top of the core downwards occurred more rapidly (D=0.8–7×10 -8 m 2 s -1, dependent on depth) than could be accounted for by simple diffusion through the peat. Vascular plants ( Molinia, Eriophorum and Carex) had well-developed roots and were adapted to water-logged conditions in that they possessed extensive aerenchymatous lacunae throughout their roots, shoots and leaves. As well as facilitating O 2 diffusion downwards to submerged tissues, this system enables rapid diffusion upwards of CH 4. This process of gaseous transport in vascular plants is subject to control by stomata. Emission rates of CO 2 and CH 4 thus show diurnal rhythms at constant temperature. Free-run of CO 2 oscillation in the dark at 15 cm depth indicates circadian clock control. The temperature sensitivity of CH 4 emission is remarkably high ( Q 10=3.0 between 10 and 20°C in the dark); in cores kept under natural conditions of temperature and daylight the daily rhythms entrain to the peat temperature cycles.