Department of Earth System Science

Measurements of atmospheric hydrogen sulfide are often made by first collecting H₂S on a paper filter impregnated with silver nitrate. Using this technique on a recent shipboard study, we observed anomalous breakthrough characteristics of sulfide, which caused us to suspect the presence of an artifact. We have investigated the interaction of various sulfur species with these filters as precursors for the artifact sulfide. Laboratory experiments indicate that OCS generates sulfide on the filters with an efficiency of 1-2% under conditions comparable to those used for field sampling in the marine boundary layer. The magnitude of the artifact increases with increasing temperature and is insensitive to humidity and insolation. It appears likely that OCS is responsible for our shipboard results. Since much of the data on H₂S concentrations in marine air have been obtained with this technique, they are most likely in error, producing overestimates of background H₂S concentrations.