A new, yet simple technique is described to obtain intact cores of blanket bog pear whilst maintaining anaerobic conditions. Apparatus was also developed which allowed these cores to be sectioned (minimum slice thickness 1.0 cm) whilst excluding O-2 from the cut sections and the remaining core material. Using these procedures the vertical distribution of methanogenesis in peat deposits was determined on a number of occasions. The success of the technique was determined by (i) comparison of CH4 production in cores sectioned anaerobically and in air and (ii) the rate of CH4 production by individual sections before and after a brief exposure to air. There was considerable between-core variability in both the rate and vertical distribution of methanogenesis, such that a direct comparison between cores was difficult. However, the rates were always lower (average 43%, range 13-74%) within the cores sectioned in air. These effects were confirmed by sectioning peat cores under anaerobic conditions and measuring the rate of CH4 production from individual peat slices both before and after a brief (5 min) exposure to air. The rate of methanogenesis was always lower (average 39%, range 9-66%) after exposure to air. Although the careful sampling and sectioning techniques increased the time required to prepare the samples for incubation the results showed the importance of exclusion of O-2 during sample manipulation.
