DIMETHYL SULFIDE EMISSIONS FROM A SEDIMENTAL MICROBIAL ECOSYSTEM SUBJECT TO DIEL VARIATIONS OF OXIC AND ANOXIC CONDITIONS - A SIMPLE MATHEMATICAL-MODEL

This modelling study relates dimethylsulfide emission from a microbial mat to the flux of dimethylsulfoniopropionate that is exuded into the interstitial space of the mat by phototrophs. Dimethylsulfoniopropion ate may be either cleaved or demethylated. Only cleavage results in th e production of dimethylsulfide, which itself is further oxidized or e scapes from the mat. The fate of dimethylsulfoniopropionate depends on the functional group composition of the mat, the physiological charac teristics of these groups, and the eco-physiological conditions oxic/a noxic and light/dark, which both vary in a diel cycle. These three fac tors are accounted for in a mathematical model of a microbial mat typi cal of the Wadden Islands of The Netherlands and Germany. Model simula tions quantify increased dimethylsulfide production under alkaline str ess as well as additional dimethylsulfoniopropionate loads. (C) 1998 F ederation of European Microbiological Societies. Published by Elsevier Science B.V.