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.

中文翻译：

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植物叶片中甲基乙烯基酮转化为甲基乙基酮和2-丁醇的排放

甲基丙烯醛（MACR）和甲基乙烯基酮（MVK）是异戊二烯引发的反应中的关键中间化合物，它们导致形成次级有机气溶胶和光化学臭氧。本研究探讨了高等植物作为这些化合物的汇和从这些化合物转化的挥发物来源的重要性。我们将四种不排放异戊二烯的植物种类暴露在几百至几百ppb的浓度的MACR和MVK中，测量了它们的吸收率，并分析了这些植物从MACR和MVK转化而来的挥发物。我们使用流通室法确定汇率。所有植物都通过气孔吸收了MACR和MVK。熏蒸MVK时，检测到两种代谢物，甲基乙基酮（MEK）和2-丁醇。MEK的转化率为26-39％，所有挥发物的转化率为33-44％。结合之前的两个相关报告的结果，我们的结果表明，从MVK到MEK的转化通常发生在广泛的植物物种中，但是转化率可能取决于植物类型，即植物物种是异戊二烯排放型还是非异戊二烯排放型。以及熏蒸浓度。这一发现还强调了在接近环境水平的较低浓度下对这些化合物进行双边交换测量的重要性。以及熏蒸浓度。这一发现还强调了在接近环境水平的较低浓度下对这些化合物进行双边交换测量的重要性。以及熏蒸浓度。这一发现还强调了在接近环境水平的较低浓度下对这些化合物进行双边交换测量的重要性。