Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan.
Environ Sci Technol. 2010 Sep 15;44(18):7096-101. doi: 10.1021/es1017569.
Methacrolein (MACR) and methyl vinyl ketone (MVK) are oxygenates produced from isoprene which is abundantly emitted by trees. The uptake rate of these compounds by leaves of three different Quercus species, Q. acutissima, Q. myrsinaefolia, and Q. phillyraeoides, at typical concentrations within a forest (several part per billion by volume) were determined. The rates of uptake of croton aldehyde (CA) and methyl ethyl ketone (MEK) were also investigated for comparison. The rates of uptake of the two aldehydes MACR and CA were found to be higher than those of the two ketones. In particular, the rate of MEK uptake for Q. myrsinaefolia was exceptionally low. The ratio of intercellular to fumigated concentrations, Ci/Ca, for MACR and CA was found to be low (0-0.24), while the ratio for the two ketones was 0.22-0.90. To evaluate the contribution of tree uptake as a sink for the two isoprene-oxygenates within the forest canopy, loss rates of the compounds due to uptake by trees and by reactions with hydroxyl radicals (OH radicals) and O(3) were calculated. The loss rate by tree uptake was the highest, followed by the reaction with OH radicals, even at a high OH concentration (0.15 pptv) both for MACR and MVK, suggesting that tree uptake provides a significant sink.
甲基丙烯醛（MACR）和甲基乙烯基酮（MVK）是异戊二烯产生的含氧物，而树木会大量排放异戊二烯。本研究测定了 3 种不同栎属植物（麻栎、栓皮栎和柳叶栎）叶片对典型森林浓度（体积分数为几个 ppb）下这两种化合物的吸收速率，同时还研究了巴豆醛（CA）和甲乙酮（MEK）的吸收速率作为比较。结果表明，两种醛类化合物 MACR 和 CA 的吸收速率高于两种酮类化合物。特别是，栎属植物 Q. myrsinaefolia 对 MEK 的吸收速率异常低。MACR 和 CA 的细胞间与熏气浓度比（Ci/Ca）较低（0-0.24），而两种酮类化合物的比值为 0.22-0.90。为评估树木吸收作为林冠内两种异戊二烯氧化物汇的贡献，计算了化合物因树木吸收和与羟基自由基（OH 自由基）及 O3 反应而损失的速率。由于树木吸收导致的化合物损失速率最高，其次是与 OH 自由基的反应，即使在高 OH 浓度（0.15 pptv）下也是如此，这表明树木吸收提供了一个重要的汇。
