Dimethyl sulfide widely varying in surface water of the eastern North Pacific

Dimethyl sulfide (DMS) in the surface ocean water of the eastern North Pacific was determined for samples collected at 23 stations in a relatively small area of about 1.2 × 105 km2, 250–550 km off the US west coast, and at 11 stations around this area, in July and early August 1988. The concentrations in the small area widely varied between 1.54 and 10.82 nM with an average of 4.10 nM (n = 23, SD = 1.97). The variation, however, was not random. The higher concentrations were found in the area between 44 and 45 °N, and in waters with temperatures between 14.5 and 16.5 °C. The DMS concentration was not significantly correlated with the chlorophyll-a concentration for all the samples, but a very weak correlation was observed for the samples collected in the small study area. These results suggested that the plankton biomass is not directly related to the DMS concentration, but there may be some biological activities controlling the concentration, for example the stage of phytoplankton growth and other factors depending on the plankton. The mean flux of DMS from sea to air has been calculated to be 0.23 mgS/m2/day.