We examined the reactive uptake of dinitrogen pentoxide (N 2 O 5 ) to authentic biomass-burning aerosol (BBA) using a small chamber reservoir in combination with an entrained aerosol flow tube. BBA was generated from four different fuel types and the reactivity of N 2 O 5 was probed from 30 to 70% relative humidity (RH). The N 2 O 5 reactive uptake coefficient, γ (N 2 O 5 ), depended upon RH, fuel type, and to a lesser degree on aerosol chloride mass fractions. The γ (N 2 O 5 ) ranged from 2.0 (±0.4) ×10 −3 on black needlerush derived BBA at 30% RH to 6.0 (±0.6) ×10 −3 on wiregrass derived BBA at 65% RH. Major N 2 O 5 reaction products were observed including gaseous ClNO 2 and HNO 3 and particulate nitrate, and used to create a reactive nitrogen budget. Black needlerush BBA had the most particulate chloride, and the only measured ClNO 2 yield > 1%. The ClNO 2 yield on black needlerush decayed from an initial value of ∼100% to ∼30% over the course of the burn experiment, suggesting a depletion of BBA chloride over time. Black needlerush was also the only fuel for which the reactive nitrogen budget indicated other N-containing products were generated. Generally, the results suggest limited chloride availability for heterogeneous reaction for BBA in the RH range probed here, including BBA with chloride mass fractions on the higher end of previously reported values (∼17–34%). Though less than fresh sea spray aerosol, ∼50%. We use these measured quantities to discuss the implications for nocturnal aerosol nitrate formation, the chemical fate of N 2 O 5 (g), and the availability of particulate chloride for activation in biomass burning plumes.
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Comparison of Airborne Reactive Nitrogen Measurements During WINTER
We present a comparison of instruments measuring nitrogen oxide species from an aircraft during the 2015 Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign over the northeast United States. Instrument techniques compared here include chemiluminescence (CL), thermal dissociation laser‐induced fluorescence (TD‐LIF), cavity ring‐down spectroscopy (CRDS), high‐resolution time of flight, iodide‐adduct chemical ionization mass spectrometry (I‐CIMS), and aerosol mass spectrometry. Species investigated include NO2, NO, total nitrogen oxides (NOy), N2O5, ClNO2, and HNO3. Particulate‐phase nitrate is also included for comparisons of HNO3and NOy. Instruments generally agreed within reported uncertainties, with individual flights sometimes showing much better agreement than the data set taken as a whole, due to flight‐to‐flight slope changes. NO measured by CRDS and CL showed an average relative slope of 1.16 ± 0.01 across all flights, which is outside of combined uncertainties. The source of the error was not identified. For NO2measured by CRDS and TD‐LIF the average was 1.02 ± 0.00; for NOymeasured by CRDS and CL the average was 1.01 ± 0.00; and for N2O5measured by CRDS and I‐CIMS the average was 0.89 ± 0.01. NOybudget closure to within 20% is demonstrated. We observe nonlinearity in NO2and NOycorrelations at concentrations above ~30 ppbv that may be related to the NO discrepancy noted above. For ClNO2there were significant differences between I‐CIMS and TD‐LIF, potentially due in part to the temperature used for thermal dissociation. Although the fraction of particulate nitrate measured by the TD‐LIF is not well characterized, it improves comparisons to include particulate measurements.
more » « less- Award ID(s):
- 1822664
- NSF-PAR ID:
- 10375356
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 124
- Issue:
- 19
- ISSN:
- 2169-897X
- Page Range / eLocation ID:
- p. 10483-10502
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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