A comparison of hydrogen sulfide, hydrogen and methane production and consumption in different aquatic ecosystems

Abstract

A survey of gas production and consumption activities in sediments and water of rivers, streams, lakes and a salt marsh determined within the last 16 years is presented. Depending on trophic conditions and degree of pollution the activities varied over a range of several magnitudes. H₂ actively produced in anaerobic sediments was detected only in traces since it was removed immediately by sulfate-reducing and methanogenic bacteria. High concentrations of H₂-oxidizing bacteria at the sediment surface prevented its escape to the water. CH₄ and H₂S production were clearly dependent on available organic matter and the presence of sulfate, which controlled the competitive relationships between these two bacterial groups. In the salt marsh and sulfate-rich rivers nearly all of the energy precursors were used by sulfate reducers, whereas in the absence of sulfate, such as the freshwater lakes and streams, methanogens outcompeted the sulfate reducers. Methane- and H₂S-oxidizing bacteria were especially evident at the sediment surface of flowing water where they were much more active than in the free water above the sediment. Only small amounts of CH4 produced in anaerobic river sediments were oxidized in the water whereas H₂S and H₂ were almost completely consumed within the aquatic ecosystems.