Humic acid addition lowers methane release in peats of the Mer Bleue bog, Canada

The effects of humic substances on methanogenesis in peats are poorly understood. In incubation experiments we added Pahokee Peat Humic Acid (DOM), a suppressor for methanogenesis (2-bromoethane sulfonic acid, BES), and BES + DOM to bog peat and studied CO2 and CH4 release. Addition of DOM lowered CH4 (p < 0.05) but not CO2 release compared to controls. BES addition suppressed CH4 release compared to controls (p < 0.01). DOM/BES addition lowered the release even further (p = 0.06) but did not induce net CH4 loss. DOM was thus utilized as electron acceptor and lowered CH4 release; anaerobic CH4 oxidation may have contributed to this effect.