Alberto Borges, oceanographer at the University of Liège, has conducted a comparative study in Belgium and Africa on the microbial oxidation of methane in rivers, a natural process in which certain bacteria consume this powerful greenhouse gas before it is released into the atmosphere. His research reveals that this biological filter, which is more active in African rivers than in Belgian rivers, remains insufficient to offset the rise in methane emissions expected because of global warming and nitrate pollution.
The findings are published in the journal Science Advances.
Rivers as a methane source
Methane (CH4) is the second most potent greenhouse gas after carbon dioxide (CO2). Rivers are a significant source of methane to the atmosphere, accounting for around a third of emissions from agriculture, the human activity contributing most to the increase in atmospheric methane.
Methane emissions from rivers result from the balance between methane production via methanogenesis—the biological process by which certain microorganisms produce methane as the end product of their metabolism—in river soils and sediments, and methane loss through microbial oxidation—the process by which microorganisms "consume" molecules to extract energy or biomass.
