Direct measurements of emission rates of some atmospheric biogenic sulfur compounds

Direct measurements of H₂S + COS and (CH₃)₂S emission rates were made in two salt marshes on the coast of North Carolina during the summer of 1977. An emission flux reactor (chamber) technique was used to determine the emission rates of sulfur compounds into the atmosphere. The sulfur gases were identified and their concentrations in the flux reactor measured with a gas chromatograph equipped with a flame photometric detector specific for S. Flux measurements were made over salt marsh grass (Spartina alterniflora) and mud flats. The predominant gaseous sulfur species being emitted over the Spartina zone is (CH₃)₂S (average flux is ~ 0.66 g S/m²/yr), and the predominant species over the mud flat zone is H₂S + COS (average flux is ~ 0.2 g S/m²/yr). In general, the emission rates of (CH₃)2S and H₂S + COS increase with increasing ambient temperature (in accordance with previously reported work over mud flats). Similar experiments were also performed in which the chamber was operated under deaerated (N₂) conditions. For deaerated conditions, the emission rates of both H₂S + COS and (CH₃)₂S were increased.