Tracking Nitrogen Oxides, Nitrous Acid, and Nitric Acid, Particulate Nitrate and Ammonia from Wildfire

Biomass burning emissions are an important source of atmospheric reactive nitrogen species such as nitrogen oxides (NO_x = NO + NO₂), nitrous acid (HONO), nitric acid (HNO₃), particulate nitrate (p-nitrate) and ammonia (NH₃). NO_x and HONO play important roles in atmospheric oxidation capacity (hydroxyl radical and ozone formation) that determines lifetime of many atmospheric trace gases and controls formation of air pollutants such as ozone and secondary aerosols in the presence of sunlight and volatile organic compounds. Along with NH₃, HNO₃ and p-nitrate are a major component of atmospheric fine particulate matter (e.g. PM 2.5 and PM 1) that pose a severe health concern and impact climate. HNO₃ and p-nitrate, via deposition, can also significantly impact water quality and ecosystem health (e.g. eutrophication).

In summer 2018, we are participating in an extensive, multi-platform and collaborative field campaign: Western wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN). As a part of the WE-CAN project, we will sample background air and smoke plumes over the course of approximately 3 weeks in the western US. Using recently developed methods, which have been validated in both laboratory and field settings, we will conduct high time resolution collection of NO_x, HONO, HNO₃, NH₃, p-nitrate, and p-ammonium for off-line isotopic analyses. The isotopes of these species offer a new tool for tracking the influence of biomass burning on the formation and chemistry of these important reactive species. In addition, we will carry out in-situ concentration measurements of NO_x, HONO, HNO₃, other soluble inorganic species, and carbon monoxide (CO). We will present comprehensive datasets generated from the concentration and isotopic measurements, which will enable us to characterize, quantify and constrain the wildfire associated reactive nitrogen species, interactions among them, and their impacts on atmospheric chemistry.