Anaerobic Methane Oxidation is Quantitatively Important in Deeper Peat Layers of Boreal Peatlands: Evidence from in situ Stable Isotopes Depth Profiles, Anaerobic Incubations, and Microbial Communities

Dataset contains complete result of laboratory anaerobic incubations with peat samples from 3 West Siberian peatlands.

Before the incubation, the peat samples were thoroughly mixed to ensure homogeneity. Aliquots (140 ± 1 g) were mixed with distilled water at a ratio of 1:2 by weight, and then placed into sterile 500 ml glass bottles, flushed with pure argon (99.9999%, Voessen, Russia) for 5 min to remove any oxygen and sealed with butyl rubber septa to maintain anaerobic conditions. The bottles were kept at +5°C for 1 day to allow the equilibration between the peat and the headspace. Then bottles were again thoroughly flushed with argon for 5 min, sealed, and an additional 5 ml of argon was added to prevent air diffusion into the bottle headspace. The incubation was performed in two different ways: i) unamended control, and ii) amended with 10 ml of CH₃F to inhibit acetotrophic methanogenesis. Peat samples from the depths of 15-20 and 40-50 cm were incubated at 15° and 10°C, respectively, for a period of 60 days, whereas deeper peat samples were incubated at 5°С, representing the temperature of the deeper peat layers of Mukhrino bog during the snow-free period for 150 days. Gas (1 mL for Н₂, CH₄ and CO₂ concentration, 1 mL for stable isotope compositions) and liquid (1 mL for organic acids) samples were taken for analysis every two weeks after manually shaking the bottles for approximately 5 s to equilibrate the gaseous and aqueous phases. At the end of the incubation, methane headspace concentrations ranged from 1 to 3 % for deeper samples. The incubations with and without CH₃F addition were carried out in three replicates for samples from Mukhrino bog and in two replicates for Chistoe and Lempino bogs. Net methane and CO₂ production were calculated from the gas concentrations, the volume of the gas space, and the water volume using the ideal gas law. Gas solubility was calculated using Henry’s law. The reported net methane and CO₂ production are the averages of 2-3 replicates.

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