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 Lagrangian experiment in the subpolar North Atlantic, at 60°N 21°W. A bloom of coccolithopores, mostly of the species Emiliania huxleyi, dominated the phytoplankton assemblage over the first week. High surface concentrations of dimethylsulfoniopropionate (DMSP, 37–70 nM) were found along with moderate DMS concentrations (3–9 nM) during the entire experiment. Rates 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 incubations 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 concentrations and transformation rates between Lagrangian samplings. Air‐sea exchange rates for DMS (0.03–3 nM d−1) were calculated from surface concentrations, seawater temperature, and wind speed. All major processes involved in the DMS cycle showed significant short‐term variability in coupling to the variability of solar radiation, wind speed, and mixing. Biotic and abiotic DMS turnover rates were of similar magnitude and very dynamic, with a prompt response to a rapidly changing physical environment. The rapid impact of meteorological forcing factors on DMS cycling provides the basis for a sulfur‐mediated, short‐term plankton/climate interaction.