Nitrous acid (HONO) is an atmospherically relevant species of interest for its role in hydroxyl generation in the atmosphere. However, the significance of the mechanisms in which HONO is formed in the atmosphere have not been established. Studies have demonstrated that HONO can be produced through photochemical reactions on organic aqueous surfaces. This mechanism serves as a major source of HONO production in the atmosphere (700 ppt hr-1). Most of these studies have been done on terrestrial derived dissolved organic matter (DOM). This reaction for the generation of HONO in terrestrial environments during the day is largely driven by the reaction of NO2 with organic aqueous surfaces in the presence of sunlight. As there is no defined structure for DOM, humic acid (Sigma Aldrich) is commonly used as a model. However, marine sources have not yet been well characterized even though over 70% of the earth is covered in oceans. In addition, studies using UV-VIS spectroscopy, mass spectrometry, NMR, etc. have shown that humic acid is an inadequate model for marine chromophoric dissolved organic matter (m-CDOM). The current experiment presented here utilizes an in-house built incoherent broad band cavity-enhanced absorption spectrometer (IBBCEAS) to directly measure the concentration of HONO production. This technique was developed to specifically study HONO production from m-cDOM and allows for direct quantification of HONO with concentrations in the tens of ppb or sub-ppb regime, which is relevant to atmospheric environments. Additionally, studying the effects from varying environmental factors (such as relative humidity, temperature, salt content, and ionic strength) using the IBBCEAS can provide insight into the mechanisms responsible for HONO formation from m-cDOM.

Development of an incoherent broadband cavity enhanced absorption spectrometer (IBBCEAS) designed for the study of marine produced HONO

2019 Fall National Meeting

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