The world's oceans have been known for several years to be a significant source of sulfur in the atmosphere. Current estimates place sulfur from marine sources at about 50% of the atmospheric sulfur attributable to human sources. However, recent work published in Geophysical Research Letters (GRL) indicates that estimates need to be refined to account for seasonal variations in the production of marine sulfur and poor understanding of air-sea interchange processes.
Dimethyl sulfide (DMS) represents more than 95% of the volatile sulfur compounds found in the ocean. Joel D. Cline and Timothy S. Bates, in the October issue of GRL, show that production of DMS in the central equatorial Pacific is strongly correlated with chlorophyll “a,” a measure of phytoplankton abundance, which is in turn associated with equatorial upwelling. The concentrations of DMS Cline and Bates found from 6°N to 6°S and from 148°W to 170°E (about 2% of the world's ocean surface area) would yield about 1% of the entire annual flux of sulfur from the ocean to the atmosphere.