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During the EXPLORE-YRD campaign (EXPeriment on the eLucidation of the atmospheric Oxidation capacity and aerosol foRmation, and their Effects in Yangtze River Delta) in May–June 2018, we measured N 2 O 5 , NO 2 , O 3 and relevant parameters at a regional site in Taizhou, Jiangsu Province. The nocturnal average NO 3 production rate was 1.01 ± 0.47 ppbv h−1, but the mixing ratio of N 2 O 5 was low, with a maximum of 220 pptv in 1 min, suggesting rapid loss of NO 3 and N 2 O 5. The nocturnal steady-state lifetime of N 2 O 5 was 43 ± 52 s on average, which may be attributed to the elevated monoterpene and fast N 2 O 5 uptake. VOCs (mainly monoterpenes) dominated daily NO 3 loss with the percentage of 36.4% and N 2 O 5 uptake accounted for 14.4%, when taking NO + NO 3 and NO 3 photolysis into consideration. We demonstrated that the nonnegligible daytime NO 3 oxidation of monoterpene in YRD region, which contributes to the daytime formation of organic nitrate and secondary organic aerosol. The daily average NO x consumption rate via rapid NO 3 reaction reached 0.63 ppbv h−1, corresponding to 57.3% NO x loss in comparison with the OH oxidation pathway at this site, highlighting the key role of NO 3 and N 2 O 5 in NO x removal and subsequent photochemistry in the YRD region. • Low N 2 O 5 was observed with a nocturnal NO 3 production rate of 1.01 ± 0.47 ppbv h−1. • Rapid losses of NO 3 and N 2 O 5 attributed to high monoterpenes and fast N 2 O 5 uptake. • NO 3 and N 2 O 5 chemistry was responsible for more than half of daily NO x removal. [ABSTRACT FROM AUTHOR]