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

本项目的重点是针叶林和大气之间的生物挥发性有机化合物（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“缺失的”有机物种的影响尚不清楚，导致模型模拟森林-大气挥发性有机碳交换的能力受到根本限制。 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。 碳是所有生命的基本元素，因此了解它如何移动有助于我们了解生物过程和影响它们的因素。本研究将解决以下科学问题：（1）针叶林在整个质谱中的活性碳通量预算是多少？这些双向通量对大气OH反应性的重要性是什么？以前未鉴定或未建模的化合物是否有重要作用？(2)如何排放和沉积的个别有机分子，类别的BVOCs（O：C比，OH速率常数，不饱和度等），和整体反应合奏，随时间变化，并作为一个功能的环境驱动程序？目前的模型在多大程度上捕捉到了这些依赖性？(3)生态系统的各个组成部分（例如，林上、林下、土壤）、林冠化学和沉积物联合收割机共同推动森林-大气总净通量收支？我们能否通过协调这些不同的术语来接近生态系统水平的BVOC通量预算？以及（4）这一整套BVOC通量对大气成分、近地面臭氧和HOx化学的更广泛的影响是什么？ 该研究计划结合了两个高分辨率的TOF-CIMS来测量针叶林整个质量范围内的树冠层BVOC通量，以评估这些通量对OH反应性的重要性。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

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.