Sulfate-methane transition zone

<p>The sulfate-methane transition zone (SMTZ) is a zone in oceans, lakes, and rivers typically found below the sediment surface in which sulfate and methane coexist. The formation of a SMTZ is driven by the diffusion of sulfate down the sediment column and the diffusion of methane up the sediments. At the SMTZ, their diffusion profiles meet and sulfate and methane react with one another, which allows the SMTZ to harbor a unique microbial community whose main form of metabolism is <a href="/facts/Anaerobic_oxidation_of_methane/ofqtfFKQ">anaerobic oxidation of methane</a> (AOM). The presence of AOM marks the transition from <a href="/facts/Dissimilatory_sulfate_reduction/MefJzUxo">dissimilatory sulfate reduction</a> to <a href="/facts/Methanogenesis/5sA0no5A">methanogenesis</a> as the main metabolism utilized by organisms.
</p><p>The SMTZ is a global feature that can occur at depths that range anywhere from a few millimeters to hundreds of meters below the sediment surface. It tends to span several centimeters, but can also reach widths up to a whole meter. It is characterized by low concentrations of sulfate and methane because the anaerobic oxidation of methane consumes both molecules.
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Sulfate-methane transition zone open-in-new

Sulfate-methane transition zone