Emissions of sulfur gases from wetlands

Abstract

Data on the emissions of sulfur (S) gases from marine and freshwater wetlands are summarized with respect to wetland vegetation type and possible formation mechanisms. The current data base is largest for salt marshes inhabited by Spartina alterniflora. Both dimethyl sulfide (DMS) and hydrogen sulfide (H₂S) dominate emissions from salt marshes, with lesser quantities of methyl mercaptan (MeSH), carbonyl sulfide (COS), carbon disulfide (CS₂) and dimethyl disulfide (DMDS) being emitted. High emission rates of DMS are associated with vegetation that produces the DMS precursor dimethylsulfonio-propionate (DMSP). Although large quantities of H₂S are produced in marshes, only a small percentage escapes to the atmosphere. High latitude marshes emit less S gases than temperate ones, but DMS is still the dominate S gas. Mangrove-inhabited wetlands also emit less S than temperate S. alterniflora marshes.

Few data are available on S gas emissions from freshwater wetlands. In most instances, S emissions from temperature freshwater sites are low. However, some temperate and subtropical freshwater sites are similar in magnitude to those from marine wetlands which do not contain vegetation that produces DMSP. Emissions are low in Alaskan tundra but may be considerably higher in some bogs and fens.