LAUSR

Methacrolein (MACR) and methyl vinyl ketone (MVK) are key intermediate compounds in isoprene-initiated reactions, and they cause the formation of secondary organic aerosols and photochemical ozone. The importance of higher plants as a sink of these compounds and as a source of volatiles converted from these compounds was addressed in the present study. We exposed four non-isoprene-emitting plant species to MACR and MVK at concentrations of several to several hundred ppb, measured their uptake rates, and analyzed the volatiles converted from MACR and MVK by these plants. We used a flow-through chamber method to determine the exchange rates. Both MACR and MVK were absorbed by all plants via stomata. Two metabolites, methyl ethyl ketone (MEK) and 2-butanol, were detected when MVK was fumigated. The conversion ratio was 26–39% for MEK and 33–44% for all volatiles. Combined with the results of two previous relevant reports, our results suggest that MEK conversion from MVK normally occurs in a wide range of plant species, but the conversion ratio may depend on plant type, i.e., if plant species are isoprene-emitting or non-emitting, as well as on the fumigation concentrations. This finding also emphasizes the importance of bilateral exchange measurements of these compounds at lower concentrations close to ambient levels.