Malin, G., Wilson, W.H., Bratbak, G., Liss, P.S. and Mann, N.H.
School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ. U.K.
Emissions of dimethyl sulfide (DMS), the major volatile sulphur compound in seawater, account for a dominant fraction of the sulfur entering the atmosphere over the open oceans. DMS atmospheric oxidation products are the major source of sub-micron aerosol particles over remote marine areas, and influence global climate by scattering and absorbing radiation, and by affecting cloud albedo. The major precursor of DMS is dimethylsulfoniopropionate (DMSP), which is a compatible solute in many marine phytoplankton. Attention has focused recently on water column microbial processes that influence DMS production, with the aim of defining the key factors that control the quantity of DMS available for sea-air exchange. In this laboratory study we looked at the effects of viral lysis on dimethyl sulfide (DMS) and particulate and dissolved dimethylsulfoniopropionate (DMSPp and DMSPd) concentrations in batch cultures of Phaeocystis pouchetii infected with a strain specific viral isolate. After 20 hours DMS concentration had increased 4-fold over the levels observed in the control cultures and this increased to 8-fold 45 hours after viral particles were added. The results will be discussed in the context of current understanding of the biogeochemical cycle of DMS in seawater.