Short-term variability in the open ocean cycle of dimethylsulfide

The marine biogeochemical cycle of dimethylsulfide (DMS), the main natural source of sulfur to the global atmosphere, was studied during a 2-week Lagr angian experiment in the subpolar North Atlantic, at 60 degrees N 21 degree s W. A bloom of coccolithopores, mostly of the species Emiliania huxleyi, d ominated the phytoplankton assemblage over the first week. High surface con centrations of dimethylsulfoniopropionate (DMSP, 37-70 nM) were found along with moderate DMS concentrations (3-9 nM) during the entire experiment. Ra tes of biological DMSP consumption (8-51 nM d(-1)) and DMS production(1-14 nM d(-1)) and consumption (0-6 nM d(-1)) were measured in short-term dark i ncubations of surface seawater. Rates of DMSP biosynthesis (11-31 nM d(-1)) and DMS photochemical loss (1-10 nM d(-1)) were estimated by budgeting con centrations and transformation rates between Lagrangian samplings. Air-sea exchange rates for DMS (0.03-3 nM d(-1)) were calculated from surface conce ntrations, seawater temperature, and wind speed. All major processes involv ed in the DMS cycle showed significant short-term variability in coupling t o the variability of solar radiation, wind speed, and mixing. Biotic and ab iotic DMS turnover rates were of similar magnitude and very dynamic, with a prompt response to a rapidly changing physical environment. The rapid impa ct of meteorological forcing factors on DMS cycling provides the basis for a sulfur-mediated, short-term plankton/climate interaction.