Non-Methane Hydrocarbon Emissions from Plants

据估计，全球植物排放的天然碳氢化合物每年约为830Tg，在对流层臭氧的产生、白天OH浓度的调节中发挥着重要作用，也是CO的前体。然而，这些生物源化合物的区域和全球清单存在许多不确定性。许多不确定性的产生是因为缺乏将碳氢化合物排放与控制这种植物排放的关键环境变量联系起来的准确数据。对于异戊二烯(2-甲基-1，3-丁二烯)的排放尤其如此，异戊二烯是植物排放的单一最丰富的碳氢化合物。可以提出许多关于NMHC排放的问题，1.植物排放的NMHC主要是什么？2.哪些环境变量控制NMHC的排放？3.环境胁迫是增加还是减少NMHC的排放？4.NMHC的生物合成有哪些生化途径？5.我们能否建立一个基于机理的模型来解释植物的NMHC排放？为什么植物会排放异戊二烯等NMHC？这项工作的主要目标是试图在植物排放异戊二烯的情况下回答这些问题。其次，该项目在排放NMHC混合物的植物中解决了这些问题的一个子集，重点是同时测量来自相同叶子的异戊二烯和单萜烯的排放。这将为单萜排放的环境控制提供新的细节。第三，在进行上述实验的同时，将同时监测丙酮、甲醇、乙醇和乙醛等含氧碳氢化合物(OxHC)的排放。这将为理解导致植物排放oxHC的生理和环境条件提供一个框架。

Natural hydrocarbon emissions from plants, estimated to be 830 Tg per year globally, play an important role in the generation of tropospheric ozone, regulation of daytime OH concentration, and are precursors of CO. However, there are many uncertainties in regional and global inventories of these biogenic compounds. Much of the uncertainty arises because there is a lack of precise data relating hydrocarbon emissions to key environmental variables that regulate such emissions from vegetation. This is especially true for emissions of isoprene (2-methyl-1,3-butadiene), the single most abundant hydrocarbon emitted from plants. Many questions can be posed concerning NMHC emissions, 1. What major NMHC are emitted from plants? 2. What environmental variables control NMHC emissions? 3. Do environmental stresses increase or decrease NMHC emissions? 4. What are the biochemical pathways for biosynthesis of NMHC and where is synthesis located in plant cells? 5. Can we develop a mechanism based model to explain NMHC emissions from plants? 6. Why do plants emit NMHC such as isoprene? The major goal of this work is to attempt to answer these questions in the case of isoprene emission from plants. Second, the project addresses a subset of these question in plants that emit a mixture of NMHC, focusing on the simultaneous measurement of isoprene and monoterpene emissions from the same leaves. This will provide new details for the environmental control for monoterpene emissions. Third, while the above experiments are conducted there will be simultaneous monitoring of emissions of oxygenated hydrocarbons (oxHC), such as acetone, methanol, ethanol and acetaldehyde. This will provide a framework for understanding the physiological and environmental conditions that lead to the emission of oxHC from plants.