A NEW SOURCE OF DIMETHYLSULFIDE (DMS) FOR THE ARCTIC ATMOSPHERE - ICE DIATOMS

We report the first evidence that pennate diatoms growing within the bottom layer of first-year ice in the Arctic produce significant amounts of particulate dimethylsulfoniopropionate (DMSP(p)) and dissolved DMSP+DMS. In 1992 in Resolute Passage, a tributary of Barrow Strait, DMSP(p) concentrations within the bottom layer of ice reached 1055 mg S m(-3) at the end of the vernal bloom, a value one order of magnitude higher than the maximum value reported in antarctic ice. Bottom-ice concentrations in DMSP(p) and DMSP(d)+DMS were significantly correlated with the abundance of the dominant pennate diatom Nitzschia frigida. Intracellular concentration in DMSP of ice algae was very low (0.001 pg cell(-1)) at the end of April when algae were light-limited and reached 1.17 pg cell(-1) in mid-May following an increase in light and algal growth. We calculate that the rapid release of the dissolved DMSP+DMS from the ice into surface waters following the ice break-up will generate a sea-to-air DMS flux of 0.7 mg S m(-2) d(-1), a pulse ten times higher than the mean arctic summer flux. We estimate that this 1-d pulse represents up to 5% of the annual DMS emission in the Arctic.