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的影响。在陆地边界层（TBL）中，气相硝酸（HONO）是由表面上的氮氧化物（NOx）和硝酸（HNO3）等前体反应产生的。这些将沉积的HNO3再循环为光化学反应性氮的过程，如HONO，通常被称为“再氧化”。在海洋边界层（MBL）中，海浪产生富含有机物和硝酸盐的海盐气溶胶。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，人们对海洋环境中HONO的分布和化学性质还不是很了解，迄今为止在MBL中只有少量的HONO现场测量报告。该项目旨在研究与海盐气溶胶相关的硝酸盐颗粒快速光解引起的再氧化反应作为HONO的来源。工作包括一系列实地测量、实验室实验和模型模拟。具体而言，研究人员将：1)在百慕大都铎山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pNO3、HNO3、NOx、气溶胶负荷、气溶胶离子成分（NO3-、Cl-、SO42-、Na+、Mg2+和Ca2+）、O3和VOCs。2)收集气溶胶样品，在实验室进行光化学实验，测定产生HONO和NO2的pNO3光解速率常数。3)通过箱体和三维化学运输模型模拟，考察pNO3光解作为HONO源和再氧化途径，并评估该过程在MBL中产生氧化剂的作用。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.