Hygroscopicity of Polycatechol and Polyguaiacol Secondary Organic Aerosol in Sub- and Supersaturated Water Vapor Environments

KOTIBA A. MALEK, Kanishk Gohil, Hind Al-Abadleh, Akua Asa-Awuku, University of Maryland

     Abstract Number: 106
     Working Group: Aerosols, Clouds and Climate

Abstract
Biomass burning is a major source of primary atmospheric aerosols whose hygroscopic and optical properties contribute to aerosols indirect and direct effect on the climate. Biomass burning is also a source of a variety of gases that lead to secondary organic aerosol (SOA) formation. During their residence time in the atmospheric, biomass burning gases and particles undergo mixing and aging processes that change their chemical and physical properties. For example, iron (Fe), which is a component of mineral dust, sea spray and biomass emissions catalyzes aqueous phase oligomerization reactions that convert phenolic compounds catechol and guaiacol into light-absorbing and water-insoluble particles, namely polycatechol and polyguaiacol. In this presentation, the cloud condensation nucleation (CCN) efficiencies of polycatechol and polyguaiacol under sub- and supersaturated environments were quantified using the single hygroscopicity parameter (κ). Our results show that both polycatechol and polyguaiacol are CCN active with κ-values ranging from 0.03 to 0.25 with polycatechol being more hygroscopic than polyguaiacol under subsaturated (κ =0.13 vs κ=0.03) and supersaturated conditions (κ =0.25 vs κ=0.16). This difference in hygroscopicity is attributed to structural differences. The implications of our results on aerosol hygroscopic properties will be presented.