Summary Sites in the West Siberian peat bog ‘Bakchar’ were acidic (pH 4.2–4.8), low in nutrients, and emitted CH 4 at rates of 0.2–1.5 mmol m −2 h −1 . The vertical profile of δ 13 CH 4 and δ 13 CO 2 dissolved in the porewater indicated increasing isotope fractionation and thus increasing contribution of H 2 /CO 2 ‐dependent methanogenesis with depth. The anaerobic microbial community at 30–50 cm below the water table produced...