N<sub>2</sub>O<sub>5</sub> uptake onto saline mineral dust: a potential missing source of tropospheric ClNO<sub>2</sub> in inland China

Abstract

Abstract. Nitryl chloride (ClNO2), an important precursor of Cl atoms, significantly affects atmospheric oxidation capacity and O3 formation. However, sources of ClNO2 in inland China have not been fully elucidated. In this work, laboratory experiments were conducted to investigate heterogeneous reactions of N2O5 with eight saline mineral dust samples collected from different regions in China, and substantial formation of ClNO2 was observed in these reactions. ClNO2 yields, φ(ClNO2), showed large variations (ranging from <0.05 to ∼0.77) for different saline mineral dust samples, depending on mass fractions of particulate chloride. In addition, φ(ClNO2) could increase, decrease or show insignificant change for different saline mineral dust samples when relative humidity (RH) increased from 18 % to 75 %. We further found that current parameterizations significantly overestimated φ(ClNO2) for heterogeneous uptake of N2O5 onto saline mineral dust. In addition, assuming a uniform φ(ClNO2) value of 0.10 for N2O5 uptake onto mineral dust, we used a 3-D chemical transport model to assess the impact of this reaction on tropospheric ClNO2 in China and found that weekly mean nighttime maximum ClNO2 mixing ratios could have been increased by up to 85 pptv during a severe dust event in May 2017. Overall, our work showed that heterogeneous reaction of N2O5 with saline mineral dust could be an important source of tropospheric ClNO2 in inland China.

Formation and impacts of nitryl chloride in Pearl River Delta

“…Figure 1 shows the variation of calculated NO3 coincided with N2O5. Elevated NO3 occurred at the first four nights with a maximum of 90 pptv (1 h time resolution), which is comparable with the reported NO3 level at other sites in Pearl River Delta (Wang and Lu, 2019;Brown et al, 2016).…”

“…CC BY 4.0 License. (Xia et al, 2021;Wang et al, 2020a;Brown et al, 2016), except the case reported on the urban canopy of Beijing(Chen et al, 2020) McDuffie et al (2018a). summarized the reported φClNO2 based on the observations, and we showed that the estimated average φClNO2 in this study is in the middle to upper end of the values reported globally(Xia et al, 2021;McDuffie et al, 2018a).…”

“…The calibration of ClNO2 measurement sensitivity has been introduced in Wang et al (2022a). In brief, a nitrogen flow (6 mL min -1 ) containing 10 ppmv Cl2 was passed over a slurry containing NaNO2 and NaCl to produce ClNO2 (Thaler et al, 2011), and NaCl was included in the slurry in order to minimize the formation of NO2 as a byproduct.…”

Direct measurement of N2O5 heterogeneous uptake coefficients on ambient aerosols via an aerosol flow tube system: design, characterization and performance

“…The CEAS has been successfully applied to measure ambient N2O5 concentration in several field campaigns and laboratory studies (Chen et al, 2020;Wang et al, 2020a;Wang et al, 2017b;Wang et al, 2020b;Wang et al, 2018b;Wang et al, 2022). a Photolytic conversion to NO through blue light before detection; b Gas chromatography equipped with a mass spectrometer and a flame ionization detector;…”

Photochemistry of phosphenic chloride (ClPO2): isomerization with chlorine metaphosphite (ClOPO) and reduction by carbon monoxide

“…Due to the important role of ClNO 2 as a major source of reactive halogen atoms in the troposphere, 19 its photochemistry at different wavelengths including dissociation and isomerization with ClONO has been studied. 20 However, the photochemistry of ClPO 2 remains yet unexplored, which is probably due to lack of a practical method for its generation in the gas phase.…”