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作用，建立了由质子转移反应质谱仪（PTR-MS）、CO2分析仪、扩散装置和叶罩组成的测量系统。对甲基丙烯醛（MACR）、甲基乙烯酮（MVK）、巴豆醛（CA）、甲基乙基酮（MEK）和甲基异丁基酮（MIBK）进行熏蒸处理。研究了金榆、麻栎、马尾松和白杨对挥发性有机化合物的吸收。当金薯叶片暴露在75 ~ 750ppbv的MIBK中时，使用该系统进行测量的总体误差小于2%。即使在最低的MIBK浓度下，超过2%的挥发性有机化合物流入叶片，这表明植物对MIBK的吸收率是可检测的和阳性的。将调查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率的确定性。在具有松弛涡积系统的阔叶林中也进行了野外测量。MACR和MVK的沉积通量均在1 ~ 10 nmol m-2s-1之间。森林排放异戊二烯，其通量为2 ~ 20 nmol m-2s-1。我们的野外测量显示，森林与周围空气动态交换挥发性有机化合物。

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.