Collaborative Research: Forest-Atmosphere Volatile Organic Compound (VOC) Exchange for a Coniferous Ecosystem - Closing the Flux Budget

该项目的重点是针叶林和大气之间生物来源的挥发性有机化合物(BVOCs)的双向交换。最近的观测包括数百种有机物种的生态系统-大气通量，远远超过目前的化学运输模型所包括的。这些“失踪的”有机物种的影响尚不清楚，导致模型在模拟森林-大气挥发性有机碳交换方面的能力从根本上受到限制。这项研究将更好地定义针叶林中发生的生态系统-大气通量，使模型能够更好地预测正在发生的碳交换。碳是所有生命所必需的元素，因此了解碳是如何运动的有助于我们理解生物过程和影响它们的因素。这项研究将解决以下科学问题：(1)针叶林质量谱上的活性碳通量收支是多少？这些双向通量对大气OH反应性的重要性是什么？以前未识别或未建模的化合物是否具有重要作用？(2)单个有机分子、BVOCs类别(通过O：C比、OH速率常数、不饱和度等)以及整个反应体系的排放和沉积如何随时间和环境驱动因素的变化而变化？目前的模型在多大程度上捕捉到了这些依赖关系？(3)单个生态系统组件(例如，盖层、林下、土壤)、冠层内化学和沉积如何结合在一起，推动整个森林-大气净通量收支？我们能否通过协调这些不同的术语来关闭生态系统级别的BVOC通量预算？以及(4)这一整套BVOC通量对大气组成、近地表臭氧和Hox化学有什么更广泛的影响？这项研究计划结合了两台高分辨率TOF-CIMS来测量针叶林整个质量范围内的树冠水平BVOC通量，以评估这些通量对OH反应的重要性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project is focused on the two-way exchange of biogenic volatile organic compounds (BVOCs) between coniferous forests and the atmosphere. Recent observations include ecosystem-atmosphere fluxes for many hundreds of organic species, vastly more than are included in current chemical transport models. The impacts of these "missing" organic species is unknown, resulting in models that are fundamentally limited in their ability to simulate forest-atmosphere volatile organic carbon exchange. This research will better define the ecosystem-atmosphere fluxes that take place in coniferous forests, enabling models to better predict the carbon exchange that is taking place. Carbon is an essential element for all life, so understanding how it moves helps us to understand biological processes and factors that influence them.This research will address the following scientific questions: (1) What is the reactive carbon flux budget across the mass spectrum for a coniferous forest? What is the importance of these two-way fluxes for atmospheric OH reactivity? Is there a significant role for previously unidentified or unmodeled compounds? (2) How do the emissions and deposition of individual organic molecules, classes of BVOCs (by O:C ratio, OH rate constant, degree of unsaturation, etc.), and the overall reactive ensemble, vary temporally and as a function of environmental drivers? To what extent do current models capture these dependencies? (3) How do individual ecosystem components (e.g., overstory, understory, soils), in-canopy chemistry, and deposition combine to drive the overall net forest-atmosphere flux budget? Can we close the ecosystem-level BVOC flux budget by reconciling these different terms? And (4) What are the broader implications of this full suite of BVOC fluxes for atmospheric composition, near-surface ozone, and HOx chemistry? The research plan combines two high-resolution TOF-CIMS to measure canopy-level BVOC fluxes across the entire mass range over a coniferous forest to assess the importance of those fluxes for OH reactivity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.