Proton transfer reaction mass spectrometry based measurement of toxic organic gas uptake by plant

为了评价高等植物对大气中挥发性有机物的去除贡献，建立了由质子转移反应质谱仪(PTR-MS)、二氧化碳分析仪、扩散装置和叶围组成的测量系统。对甲基丙烯醛(MACR)、甲基乙烯基酮(MVK)、巴豆醛(CA)、甲乙酮(MEK)和甲基异丁基酮(MIBK)进行了熏蒸处理。研究了金针茅、麻栎、没食子和高山栎对挥发性有机化合物的吸收情况。当一片金黄果叶暴露在75~750 ppbv的MIBK中时，该系统测量的总误差为&lt；2%。即使在最低的MIBK浓度下，流入的VOC也有2%以上流失到叶片，这表明植物对MIBK的吸收是可检测的和正的。将研究结果与基于气相色谱分析的测量系统进行了比较，结果表明，使用基于PTR-MS的系统可以显著提高测定植物吸收VOC速率的确定性。野外测量也是在具有松弛的涡流积累系统的阔叶林中进行的。MACR和MVK的沉积通量均在1~10nmolm-2s-1范围内。森林排放异戊二烯，通量在2~20nmolm-2s-1之间。我们的野外测量显示，森林与环境空气中的VOCs动态交换。

In order to evaluate the contribution that higher plants make to the removal of volatile organic compounds from the atmosphere, a measurement system consisting of a proton transfer reaction mass spectrometer (PTR-MS), CO2 analyzer, diffusion devise and leaf enclosure was established. Methacrolein (MACR), methyl vinyl ketone (MVK), croton aldehyde (CA), methyl ethyl ketone (MEK) and methylisobuthylketone (MIBK) were fumigated. The uptake of VOCs by Epipremnum aureum, Quercus acutissima, Q. myrsinaefolia and Q. phillyraeoides was investigated.The overall error associated with measurements made using this system was <2% when a Golden Pothos leaf was exposed to 75 to 750 ppbv of MIBK. Even at the lowest MIBK concentration, more than 2 % of the inflowing VOC was lost to the leaf, representing a detectable and positive MIBK uptake rate by the plant. The results of the investigation were compared with a measurement system based on gas chromatography analysis and it was shown that the use of a PTR-MS based system can significantly increase the certainties in determining the rate of VOC uptake by plants. Field measurements were also conducted in a mixed broad leaved forest with a relaxed eddy accumulation system. The deposition fluxes of MACR and MVK were both in the range of 1〜10 nmol m-2s-1. The forest emitted isoprene, of which flux ranged from 2〜20 nmol m-2s-1. Our field measurements revealed that the forest dynamically exchanged VOCs with ambient air.