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 whereby certain bacteria consume this powerful greenhouse gas before it is released to the atmosphere. His research reveals that this biological filter, which is more active in African rivers than in Belgian ones, remains insufficient to offset the rise in methane emissions expected because of global warming and nitrate pollution.
Methane (CH ₄ ) is the second most potent greenhouse gas after carbon dioxide (CO ₂ ). Rivers are a significant source of methane to the atmosphere, accounting for around a third of emissions from agriculture, which is 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 the loss of methane through microbial oxidation – the process by which microorganisms ‘consume’ molecules to extract energy or biomass. Methane is a simple, energy-rich molecule (as evidenced by its use as a fuel in the form of natural gas), making it a preferred substrate for certain bacteria specialised in using methane as a source of energy and biomass. These bacteria can consume methane before it reaches the atmosphere.
However, microbial methane oxidation remains largely understudied. An expert in the field of the methane cycle, Alberto Borges , researcher at ULiège, investigated the issue. “We conducted a study in Belgium and Africa to characterise the variability of microbial methane oxidation in rivers. We have shown that oxidation is more significant in African rivers than in Belgian rivers; the latter are heavily disrupted by riverbank development, which reduces the input of microbial communities from the soil into the rivers, as well as by the intense filtration by the Asian corbicula, an invasive species of bivalve."
The study conducted at ULiège also showed that microbial methane oxidation is very low in headwater rivers, even though these are responsible for the vast majority of methane emissions from rivers to the atmosphere. This led us to conclude that the expected increase in methane production in response to global warming or eutrophication (nitrate pollution) will unfortunately not be offset by microbial oxidation, which nevertheless acts as a natural filter for methane emissions. This natural filter is further diminished by human perturbation of the natural functioning of rivers (riverbank engineering and the presence of invasive filter-feeding species).
Science Advances
Methane oxidation in in African and European rivers depends on stream size and wetland connectivity
17-Jul-2026