Bringing Real-World Chemical Complexity to the Laboratory – Secondary Organic Aerosol Formation from Plant Emissions Increases Particle Viscosity and Alters Composition

Prof. Celia Faiola, Univ. of California-Irvine

"Climate change is influencing ecosystem health and plant biogeography. This affects the composition and spatiotemporal distribution of biogenic volatile organic compounds (BVOCs) across Earth’s surface. Perturbations to the types of compounds emitted could have significant impacts on secondary organic aerosol (SOA) production, but the chemistry of many of these compounds (including complex mixtures of these compounds) have not been studied comprehensively in a controlled laboratory environment. This presentation will summarize laboratory studies investigating SOA formation from complex mixtures of real plant emissions representing different plant emission types. Unexpected effects on aerosol chemistry, composition, and properties attributed to the presence of oxygenated monoterpenes and acyclic terpenes in the BVOC mixture were observed. Oxygenated monoterpenes (i.e. camphor and eucalyptol) that dominate emissions from sage and sagebrush produce SOA with more highly oxygenated molecules than SOA formed from more traditionally-studied terpenes. Acyclic terpenes (i.e. myrcene and farnesene) that are often associated with plant stress, reduce SOA yields and promote fragmentation reactions while increasing the viscosity of the resulting SOA. Aerosol chemistry of these compounds could become increasingly important with the expansion of drought-tolerant sage scrub and elevated frequency of plant stress conditions."