Formation and exchange of nitrous acid at atmospheric interfaces: Understanding a critical reactive air quality intermediate

人类活动在全球范围内显著增加和改变了活性氮（Nr）的循环。可移动的Nr导致了一系列的环境循环和交换。对推动地球系统隔间内和之间Nr运动的化学，物理和生物过程的基本理解对于在现代社会中有效利用Nr，同时减轻其遗产和未来的有害影响至关重要。最近，Nr种亚硝酸（HONO）已被确定在地球表面和大气之间进行交换。HONO在清晨的光解可以启动和/或主导大气的氧化能力，这取决于环境和季节。氧化决定了排放到大气中的化学品的寿命，是用于预测气候和空气质量的化学模型的基础。在界面处，HONO交换通过级联扰动本地环境和连接组件的Nr池。许多实验室研究已经发现了可能有助于HONO交换的化学、物理和生物机制。然而，对真实的世界的观察目前无法区分其中哪些是主要机制。在环境条件下，交换过程预计会在昼夜到季节的时间尺度上发生变化，这使得HONO化学的预测成为大气化学和地球化学中的一个关键问题。我的研究小组正在定制最先进的科学分析工具，以实现在现实世界条件下界面所需的HONO测量。我们将通过定制和优化飞行时间化学电离质谱仪（ToF-CIMS）的检测，推进测量HONO交换的状态，以使涡度协方差通量。我们将创新一个最佳的采样入口，以及在部署现场测量时自动添加标准品进行校准和干扰跟踪。该平台将通过实地相互比较进行验证，然后用于量化富氮农业土壤上的HONO通量测量。ToF-CIMS平台将与用于反应气体的自动界面通量室集成，以弥补当前实验室和现场能力的局限性。这些腔室将用于在周围环境条件下进行交换机制实验，使我们能够系统地识别控制界面HONO交换的主要过程。我们的实验室还将用于研究在室内环境中发现的材料的HONO交换机制，在室内环境中经常发现非常高的HONO水平。这项工作将涉及7名研究生（4名博士，3名硕士）和8名本科生。通过在实验室和现场开发和应用创新的新分析方法，我的团队将提供对有效环境监管至关重要的基本化学知识。

Human activities have dramatically increased and altered the cycling of reactive nitrogen (Nr) at a global scale. Mobilized Nr causes a cascade of environmental cycling and exchange. Fundamental understanding of the chemical, physical, and biological processes driving the movement of Nr within and between Earth system compartments is critical to effectively utilize Nr in modern society, while mitigating both its legacy and future detrimental impacts. Recently, the Nr species nitrous acid (HONO) has been determined to undergo exchange between the Earth's surface and atmosphere. Photolysis of HONO in the early morning can initiate and/or dominate the oxidative capacity of the atmosphere, depending on environment and season. Oxidation sets the lifetime of chemicals emitted into the atmosphere and is fundamental to chemical models used to predict climate and air quality. At the interface, HONO exchange perturbs the Nr pool of the local environment and connected components via the cascade. Chemical, physical, and biological mechanisms that might contribute to exchange of HONO have been found from many laboratory studies. Real world observations, however, are not currently capable of distinguishing which, if any, of these are the major mechanism(s). Under ambient conditions exchange processes are expected to vary across diurnal to seasonal timescales, making prediction of HONO chemistry a critical issue in atmospheric chemistry and biogeochemistry. My research group is customizing state-of-the-science analytical tools to achieve the HONO measurements needed at the interface under real-world conditions. We will advance the state of measuring HONO exchange to make eddy covariance fluxes, by customizing and optimizing its detection with a time-of-flight chemical ionisation mass spectrometer (ToF-CIMS). We will innovate an optimal sampling inlet, as well as automation of standard additions for calibration and interference tracking when deployed for field measurements. The platform will undergo validation through field intercomparison before being used to quantify HONO flux measurements over Nr-rich agricultural soils. The ToF-CIMS platform will be integrated with automated interface flux chambers for reactive gases to bridge the limitations of current lab and field capabilities. The chambers will be used to conduct exchange mechanism experiments under ambient environmental conditions, allowing us to systematically discern the major processes controlling HONO exchange at the interface. Our chambers will be also be used to investigate HONO exchange mechanisms on materials found throughout the indoor environment, where very high HONO levels are regularly found. This work will involve a total of 7 graduate (4 PhD, 3 MSc) and 8 undergraduates. Through development and application of innovative new analytical methods in the lab and field, my group will provide fundamental chemical understanding that is essential to effective environmental regulation.