Factors controlling emission of dimethylsulphide from salt marshes

Abstract

The emission of biogenic sulphur gases constitutes about half the atmospheric budget for gaseous sulphur¹. Since dimethylsulphide (DMS) was first implicated as a major component of gaseous sulphur flux^2–4, considerable attention has been given to its emission from various ecosystems. Salt marshes have been identified as one system with a high area-specific sulphur emission^5–13. Dimethylsulphide and hydrogen sulphide (H₂S) constitute the bulk of the flux from salt marshes, with DMS predominating in vegetated areas of the marsh^6,8–13. As H₂S is a product of anaerobic decomposition in sediments, it has been assumed that other sulphur gases emitted from salt marshes also originate from decomposition in sediment processes⁵. Our research suggests an alternative explanation for DMS fluxes. We have investigated the distribution of DMS and dimethy Isulphoniopropionate (DMSP) in salt marshes and conclude that DMS arises primarily from physiological processes in leaves of higher plants, mainly one species of grass, Spartina alterniflora. Furthermore, the emission of DMS from this grass may be influenced by the technique used to measure emission, and emission from sites dominated by S. alterniflora cannot be considered to be representative of marsh flora.