Vegetation emits a class of oxygenated hydrocarbons � the green leaf volatiles (GLVs) � from the biochemical conversion of linoleic and linolenic acid within plant cells. Under vegetative stress or damage, emission fluxes of these compounds can be significantly elevated. Fog events over vegetation will lead to the uptake of GLVs into water droplets, potentially followed by aqueous-phase reactions with photochemically generated oxidants such as hydroxyl radical (OH) to form secondary organic aerosol (SOA).  In order to determine if GLVs can be a significant source of secondary organic carbon in fogwater, studies of GLVs in laboratory solutions are needed to elucidate kinetics for oxidation and the corresponding SOA mass yields. In this study we are determining the second-order rate constants, as well as the SOA mass yields, for a series of GLVs (cis-3-hexen-1-ol, cis-3-hexenylacetate, methyl salicylate, methyl jasmonate, and 2-methyl-3-butene-2-ol) reacting with oxidants such as OH. Experiments were performed at relevant fog water pHs, temperatures, and oxidant concentrations. Rate constants were determined using a relative rate approach in which the decay of GLVs and reference compounds are monitored as function of time by HPLC. SOA mass yields were measured gravimetrically from laboratory solutions containing atmospherically relevant concentrations of photooxidants and GLVs, and irradiated with simulated natural sunlight. In conjunction with collaborators from LSU, we will use our results to assess the potential contribution of aqueous GLV reactions as a source of SOA in cloudy or foggy atmospheres.

Oxidation of green leaf volatiles in fog water, part 2: Reaction kinetics

245th National Meeting (2013)

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