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Atmo-ecometabolomics of Healthy and Stressed Riparian Shrubs: From the Plant Metabolome to Aerosol Production
FARZANEH KHALAJ, Alber Rivas-Ubach, Christopher Anderton, Swarup China, Kailen Mooney, Celia Faiola, University of California, Irvine
Abstract Number: 103
Working Group: Aerosol Chemistry
Abstract
Vegetation contributes to production of secondary organic aerosol (SOA) via atmospheric processing of plant volatile emissions. SOA alters atmospheric radiative properties and thereby influences ecosystem function. Thus, there are tight ecosystem-atmosphere interactions linked through the plant metabolome that influence atmospheric composition and ecological processes, what we refer to as the “atmo-ecometabolome”.A better understanding of climate change effects on ecosystem function and SOA production could be achieved with a holistic atmo-ecometabolomics study approach. Within that framework, this study investigated the influence of aphid herbivory on the plant metabolome, volatile emissions, and SOA production of a common riparian shrub in California,Baccharis salicifolia–the first study to concurrently characterize these three components. The leaf-level metabolome was characterized using GC-MS and LC-MS. SOA was generated from plant emissions using an oxidation flow reactor (OFR).Chemically-speciated plant volatiles were characterized via thermo-desorption GC-MS-FID. Particle composition and size distributions were measured continuously with an aerosol chemical speciation monitor (ACSM) and scanning mobility particle sizer (SMPS), respectively. Results demonstrated that aphid herbivory significantly altered the leaf-level metabolome, and although there were some clear links between the leaf-level metabolome and volatile emissions, there was high intra-group variability in the volatile profile and SOA formation that hindered identification of clear herbivore effects. Of particular interest, SOA mass yield curves displayed as much variation within treatment groups as between treatment groups. The contribution of acyclic monoterpenes in the emission profile, such as beta-ocimene and beta-myrcene, were correlated with reduced SOA mass yield, but the relative contribution of acyclic monoterpenes was unrelated to herbivore treatment in this case. This study sheds light on the plant volatile structures controlling SOA formation from complex mixtures of plant volatiles, and can be used to improve predictions of SOA production in a future climate.