UC Irvine

Simultaneous shipboard measurements of atmospheric dimethylsulfide and hydrogen sulfide were made on three cruises in the Gulf of Mexico and the Caribbean. The cruise tracks include both oligotrophic and coastal waters and the air masses sampled include both remote marine air and air masses heavily influenced by terrestrial or coastal inputs. Using samples from two north-south Caribbean transects which are thought to represent remote subtropical Atlantic air, mean concentrations of DMS and H2S were found to be 57 pptv (74 ng S m-3, σ=29 pptv, n=48) and 8.5 pptv (11 ng S m-3, σ=5.3 pptv, n=36), respectively. The ranges of measured concentrations for all samples were 0-800 pptv DMS and 0-260 pptv H2S. Elevated concentrations were found in coastal regions and over some shallow waters. Statistical analysis reveals slight nighttime maxima in the concentrations of both DMS and H2S in the remote marine atmosphere. The diurnal nature of the H2S data is only apparent after correcting the measurements for interference due to carbonyl sulfide. Calculations using the measured ratio of H2S to DMS in remote marine air suggest that the oxidation of H2S contributes only about 11% to the excess (non-seasalt) sulfate in the marine boundary layer. © 1988 Kluwer Academic Publishers.