Non-Methane Hydrocarbon Emmissions from Plants

ATM-9312153下降虽然每年有大量的挥发性有机化合物(VOC)从植物释放到大气中，但尚不清楚植物为什么要花费大量的能量来合成挥发性和活性VOCs。这些排放塑造了全球热带化学，这一事实突显了发展对调节排放的基本过程的理解的重要性。由于人类的影响，植物的进化条件与当今整个工业世界的条件有很大不同。在我们更好地了解导致这些化合物排放的基本机制之前，我们将无法评估这些不断变化的条件目前对植被的影响，或者这些植物及其排放将如何应对进一步的全球变化。这项研究将解决三个基本问题：1)主要类型的VOCs生物合成和排放到大气的潜在机制是什么？2)调节VOC排放的主要物理和生物“驱动因素”是什么？3)VOCs如何离开植物表面？拟研究的生物来源挥发性有机化合物包括构成自然排放的主要有机物：非甲烷烃、异戊二烯和单萜烯；以及氧化烃、甲醇、乙醇、乙醛、丙酮、2甲基-3-丁烯-2-醇(甲基丁烯醇)和己烯醇族(己烯醛、乙酸己烯酯)。例如，详细的实验将检查：2)甲醇、丙酮甲基丁烯醇和异戊二烯生物合成的机制；b)异戊二烯是一种“泄漏”的代谢中间体的可能性，而叶子可能解释为什么异戊二烯排放植物从高排放者到低排放者：以及c)光、温度、湿度、二氧化碳浓度、气孔导度和叶片发育作为VOC排放的主要“驱动因素”的作用。此外，还将进行实验，以确定角质层表面和气孔孔在挥发性有机化合物从叶片中排出中的作用，包括从针叶针叶中释放单萜。这些研究应该为工厂如何以及为什么排放VOCs提供新的见解，减少关于排放“驱动因素”的不确定性，并能够预测未来VOC排放以应对全球变化。

ATM-9312153 Fall Although tremendous quantities of volatile organic compounds (VOCs) are released from vegetation into the atmosphere annually, it is not clear why plants expend a considerable amount of energy synthesizing volatile and reactive VOCs. The fact that these emissions shape global tropspheric chemistry underscores the importance of developing an understanding of the underlying processes that regulate emissions. Plants evolved under conditions which, due to man's influence, are much different that present day conditions throughout the industrial world. Until we better understand the basic mechanisms that are responsible for the emission of these compounds, we will not be able to assess the effects that these changing conditions have on vegetation currently, or how these plants and their emissions will respond to further global change. This research will address three fundamental questions: 1) What are the underlying mechanisms for the biosynthesis and emission of major classes of VOCs to the atmosphere? 2) What are the major physical and biological "drivers" that regulate VOC emissions? 3) How do VOCs exit plant surfaces? The biogenic VOCs to be studied include those organics that make up the majority of natural emissions: the non-methane hydrocarbons, isoprene and monoterpenes; and the oxygenated hydrocarbons, methanol, ethanol, acetaldehyde, acetone, 2 methyl-3-buten-2-ol (methyl butenol), and the hexenal family (hexenal, hexenyl acetate). For example, detailed experiment will examine; 2) the mechanisms of methanol, acetone methyl butenol, and isoprene biosynthesis; b) the possibility that isoprene is a "leaky" metabolic intermediate and that leafiness may explain why isoprene-emitting plants range form high to low emitters: and c) the role of light, temperature, humidity, carbon dioxide concentration, stomatal conductance and leaf development as major "drivers" of VOC emissions. In addition, d) experiments will be conducted to establish the role of cuticle surfaces and stomatal pores in the exit of VOCs from leaves, including the emission of monoterpenes from conifer needles. These studies should provide new insights into how and why plants emit VOCs, reduce uncertainties about the "drivers" of emissions, and allow prediction of future VOC emissions in response to global change.