Research Interests: Influence of Ecosystem Disturbance on Atmospheric Chemistry Processes; Influence of Terrestrial Ecosystem Phenology on Atmospheric Chemistry Processes; Secondary Organic Aerosol Formation; Biosphere-Atmosphere Interactions; Biological Production and Release of Biogenic Volatile Organic Compounds; Secondary Organic Aerosol Formation and Chemical Composition; Plant Stress Responses to Drought, Air Pollution, and Herbivory; Plant-Plant Communication via Airborne Signaling
PLANT VOLATILE EMISSIONS, ATMOSPHERIC AEROSOL, AND GLOBAL CHANGE
Research in the Faiola laboratory broadly explores topics related to plant volatile emissions in a changing climate, and how changes to plant emissions alter atmospheric chemistry processes. In particular, we investigate the influence of plant volatile emissions on the production of secondary organic aerosol (SOA) and its climate-relevant properties, which can generate feedbacks influencing ecosystem health and land-atmosphere volatile fluxes. SOA is formed from the atmospheric oxidation of plant volatile emissions, which generates lower volatility oxidation products that undergo gas-particle partitioning in the atmosphere. The Faiola lab’s research focuses on the following three broad themes.
1) Plant Stress Emissions and Atmospheric Aerosol Formation.
One of the largest uncertainties in climate change projections are associated with the radiative forcing from atmospheric aerosol. This uncertainty is due, in part, to the complex processes associated with the biota’s role in the formation of secondary organic aerosol (SOA)—including climate change feedbacks related to plant stress. Our lab conducts SOA studies in the laboratory using real plant emissions as an SOA precursor and compares SOA production between healthy and stressed plant emissions. Our work has shown that sesquiterpenes play a particularly important role in controlling SOA production from a complex mixture of real plant volatiles. In particular, our work was the first to demonstrate that acyclic sesquiterpene emissions induced after aphid stress promote fragmentation reactions (as opposed to functionalization reactions), which ultimately decrease SOA production during ozonolysis chemistry. We also explore resulting climate-relevant properties of SOA produced under these different conditions, including particle composition and viscosity.
PICTURE: 7-year old Scots pine sapling with mesh enclosure to hold bark-boring pine weevils.
2) Identifying and Characterizing Missing Sources of Plant Volatile Emissions.
Traditional studies of atmospheric aerosol formation from plant volatile emissions have focused on simplified chemical systems using an individual standard compound to represent plant emissions or have targeted field observations over a limited number of ecosystem types. This means we could be missing important sources of plant volatiles in our models. We investigate SOA formation chemistry using real plant volatile emissions as an SOA precursor to identify important compounds contributing to particle production that may have been overlooked. We conduct these experiments using a range of different plant functional types.
Another source of missing plant volatiles in emission models could be attributed to plant-microbe interactions. We are currently exploring the role of the plant microbiome (particularly the phyllosphere) in modulating plant volatile emissions.
PICTURE: Baccharis salicifolia growing in the UCI greenhouse for laboratory experiments.
3) Urban Ecology, Urban Greening, and Atmospheric Aerosols.
Urban greening programs are becoming increasingly popular, but it isn’t clear which trees should be targeted for these planting programs. Different plants emit very different types of volatile compounds which could all influence SOA production, composition, and toxicity. To address this topic, we investigate SOA formation and particle toxicity from a range of plant volatile emissions representing different plant functional types.
PICTURE: Schematic showing some of the important impacts of urban greening programs on air quality that policymakers should be considering.