Reactivity and Loss Mechanisms of NO₃ and N₂O₅ at a Rural Site on the North China Plain

Abstract

NO3, NO2, O3, and relevant parameters were measured at a rural site on the North China Plain during June 2014. During the campaign, the average concentrations of NO3 and N2O5 were 4.8 ± 3.3 pptv and 30.5 ± 35.4 pptv, respectively. The average NO3 production rate was 1.03 ± 0.48 ppbvh−1, and the steady-state lifetimes of NO3 and N2O5 were 26 s and 162 s, respectively, indicating that the NOx chemistry in the rural site during summer was active. The uptake coefficient range of N2O5 was 0.023 to 0.118, with an average value of 0.062 ± 0.035. Meanwhile, the fitting for kNO3 was 0.013 ± 0.016 s−1, corresponding to the shorter NO3 lifetime below 1 min. The results show that the indirect loss pathways caused by the heterogonous uptake of N2O5 contributed 64–90% of the overall NO3 loss, with an average of 81%, suggesting that the N2O5 heterogeneous reaction dominated the nocturnal NOx loss over this region.

Keywords

• NO₃
• dinitrogen pentoxide
• nighttime chemistry
• loss mechanisms
• heterogonous reaction