Collaborative Research: An Investigation into Daytime HONO Chemistry in the Marine Boundary Layer

气相中活性氮的量对大气的氧化能力有显著影响。在陆地边界层（TBL）中，气相亚硝酸（HONO）是由氮氧化物（NOx）和硝酸（HNO 3）等前体在表面上的反应通过各种机制产生的。这些将沉积的HNO 3再循环为光化学反应性氮物质（如HONO）的过程通常称为“再氧化”。“在海洋边界层（MBL）中，海浪产生海盐气溶胶，这些气溶胶高度富集有机物和硝酸盐。这些颗粒可以作为光化学和非均相反应的反应介质，导致HONO的形成。然而，HONO在海洋环境中的分布和化学性质尚未得到很好的了解，迄今为止，在MBL中仅报告了几次HONO的实地测量。本项目的目的是研究作为HONO来源的海盐气溶胶中硝酸盐微粒的快速光解所产生的再氧化作用。具体而言，研究人员将：1）在百慕大的Tudor Hill海洋大气观测站进行测量，并在2019年春季和夏末建立MBL中HONO的时间分布。工作将包括收集气象参数和测量pNO 3、HNO 3、NOx、气溶胶负荷、气溶胶离子成分（NO3-、Cl-、SO 42-、Na+、Mg 2+和Ca 2+）、O3、2）收集气溶胶样品，并利用它们在实验室进行光化学实验，以确定导致HONO和NO2产生的pNO 3的光解速率常数。进行箱和三维化学传输模型模拟，以检查pNO 3光解作为HONO源和再氧化途径，并评估该过程在MBL氧化剂生产中的作用。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。

The amount of reactive nitrogen in the gas phase has a significant impact on the oxidative capacity of the atmosphere. In the terrestrial boundary layer (TBL), gas phase nitrous acid (HONO) is produced by various mechanisms from reactions of precursors like nitrogen oxides (NOx) and nitric acid (HNO3) on surfaces. These processes, which recycle deposited HNO3 to photochemically reactive nitrogen species, such as HONO, are often called "renoxification." In the marine boundary layer (MBL), ocean waves produce sea salt aerosols that are highly enriched in organic matter and nitrate. These particles may serve as reactive media for photochemical and heterogeneous reactions leading to HONO formation. However, the distribution and the chemistry of HONO in marine environments are not well understood, with only a few field measurements of HONO reported in the MBL to date. This project aims to investigate renoxification resulting from rapid photolysis of particulate nitrate associated with sea-salt aerosol as a source of HONO. Work includes a series of field measurements, laboratory experiments and model simulations.Specifically, researchers will: 1) Conduct measurements at Tudor Hill Marine Atmospheric Observatory in Bermuda and establish the temporal distribution of HONO in the MBL in spring and late summer of 2019. Work will include collecting meteorological parameters and measurements of pNO3, HNO3, NOx, aerosol loading, aerosol ionic components (NO3-, Cl-, SO42-, Na+, Mg2+, and Ca2+), O3, and VOCs.2) Collect aerosol samples and use them to conduct photochemical experiments in the laboratory for the determination of the photolysis rate constant of pNO3 leading to HONO and NO2 productions.3) Conduct box and 3D chemical transport model simulations to examine pNO3 photolysis as a HONO source and as a renoxification pathway, and to evaluate the role of this process in oxidant production in the MBL.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.