Anaerobic oxidation of methane in freshwater ecosystems

Anaerobic oxidation of methane (AOM) is a biochemical process that plays an important role in aquatic ecosystems, as it significantly reduces the emission of methane (CH4 ) to the atmosphere. Under anaerobic conditions, CH4 can be oxidized with electron acceptors, such as sulphates (SO4^2-), nitrates (NO3^-) or nitrites (NO2^-), iron (Fe³⁺), manganese (Mn⁴⁺) and humic substances. The anaerobic oxidation of methane is mainly regulated by anaerobic methanotrophic archaea (ANME) and sulphate reducing bacteria. The AOM process is crucial to understand the CH4 cycle and anticipate future emissions of the gas from water reservoirs. The process is widely described in marine environments, however very little is known about its occurrence and importance in freshwater systems. There is a great demand for this kind of the research, especially in ecosystems exposed to long-term anaerobic conditions, which may be in degraded reservoirs.