| Abstract | Biomass burning events influence photochemistry and ozone production due to substantial emissions of particulate matter, ROx (OH, HO₂, and RO₂) precursors, VOCs, and NOx. Dependent on these emissions are the key ozone precursor of peroxy radicals (HO₂ and RO₂). These peroxy radicals are essential in determining tropospheric ozone formation due to their reaction with nitric oxide (NO) to produce nitrogen dioxide (NO₂). However, there exists a large knowledge gap in the area of radical photochemistry as measurements of any ROx species are extremely limited in regard to biomass burning plumes. We present results from a field study in the rural low-NOx environment of McCall, Idaho in 2018 which experienced smoke from several aged biomass burning plumes. Measurements of peroxy radicals, which were made using an ethane-based chemical amplification instrument known as ECHAMP, along with a variety of other photochemically relevant compounds have been used here to evaluate photochemical parameters including instantaneous ozone production (P(O₃)) during times of biomass burning influence. While ozone and peroxy radical enhancements from biomass burning were observed, background NOx concentrations were low (typically ~0.1 ppbv NO) with minimal enhancements from biomass burning. This indicates increases in ozone production during times of biomass burning influence with P(O₃) rates being very small overall (<4 ppb hr⁻¹). |
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