This process also affects the pH of the water. The production of methane is much more common in freshwater systems. This ion is used by plants or is washed away by runoff. Nitrosomonas is the species of bacteria responsible for the conversion of ammonia to nitrite, and Nitrobacter converts nitrite to nitrate. Rhizobia associations and algae also fix nitrogen to bring into the system.
Plants can take up nitrate or ammonia forms of nitrogen.
This gas is released when soil is disturbed, or is released slowly into the atmosphere. Wetlands are one of the only places where N2 is produced, this is important for the ecosystem. The sulfur cycle involves the conversion of organic sulfur into H2S which is stored in soil. H2S can also be released into the atmosphere or oxidized to sulfate in the aerobic zone. Sulfate is taken up by plants or washed away by runoff.