Aqueous chemistry within atmospheric aerosols has been proposed as a significant source of secondary organic aerosol (SOA) formation. SOA may play an important role in climate, air quality, and public health and the research community is gaining a fundamental understanding of the photo-oxidation pathways that produce SOA. This research aims to understand whether SOA formation processes that are known to occur in atmospheric aerosols may also occur in/on snow and ice. It is known that snow and ice are chemically active media and contain chemical species that could not only form SOA, but also react with SOA through photochemical processes and alter the snow and ice composition. These processes could have important climate implications in polar regions, because the release of volatile or semi-volatile species from snowpack could impact cloud formation processes.  Formation of “brown carbon” within snow through SOA-type chemistry could also lower the albedo of the snow/ice surface. Finally, the reactions of SOA-like products formed in ice or snow could generate oxidants and lead to production of volatile organics into the atmosphere, which could impact other atmospheric processes.<br/>            This work investigates the chemistry of known organic aerosol precursors (such as glyoxal) and other model organics prepared in both liquid and frozen aqueous conditions. To mimic aqueous SOA chemistry, these organics are exposed to an oxidant and photochemically reacted in both liquid and frozen conditions. In addition, light and dark controls are used to determine the effect of photochemical pathways. The variation of sample pH will be used to assess the effect of increased acidity. Preliminary results indicate that the presence of ammonium leads to production of a visible light absorbing species within ice. We will discuss kinetics of SOA-like product formation in ice versus liquid, characterization of products, and possible mechanisms of “brown carbon” and product formation.<br/>

Formation of brown carbon in snow and ice through SOA-like chemistry

253rd National Meeting (2017)

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