Atmospheric Chemistry Program Seminar
The Role of H2S in Photochemical Methane Haze Experiments
"Although sulfur gases and organic haze from methane photochemistry are thought to be present in numerous planetary atmospheres, including the atmosphere of the Archean Earth (2.5-3.5 bya), direct interactions between their chemistries have historically been neglected. This assumption may limit the understanding of atmospheric sulfur and organic haze chemistry, and it would therefore be beneficial to examine photochemical haze production with sulfur gases present. Organic haze laboratory studies including H2S, an atmospheric sulfur gas with both biogenic and abiogenic (e.g. volcanic) sources, have until now been non-existent. To better understand the role of H2S in organic haze chemistry, I have conducted UV photochemistry experiments of CH4 gas mixtures in N2 with the inclusion of trace amounts of H2S. I investigated the product aerosol composition, number, and size distribution as a function of H2S mixing ratio. It was found that increasing the H2S mixing ratio increased the organic aerosol effective density, number, and mass loading. Further, organic sulfur compounds were found to form in the aerosol phase. I will discuss the importance of these findings in the context of organic haze and sulfur chemistry, possible mechanisms, and future steps for the project."