Impacts of Additional HONO Sources on Concentrations and Deposition of NO_y in the Beijing-Tianjin-Hebei Region of China

Abstract

This study applies the chemistry version of the Weather Research and Forecasting model (WRF-Chem) to examine impacts of three additional HONO sources, i.e., the reaction of photoexcited NO 2 (NO 2 * ) with water vapor (NO 2 * chemistry), the NO 2 heterogeneous reaction on aerosol surfaces and HONO emissions, on concentrations and deposition of individual NO y species over the Beijing-Tianjin-Hebei region (BTH) in summer and winter periods of 2007. The results show that the three additional HONO sources produce a 20%~40% (> 100%) increase in monthly-mean OH concentrations in many urban areas in August (February), leading to a 10%~40% (10%~100%) variation in monthly-mean concentrations of NO x , NO 3 − and PAN, a 5%~10% (10%~40%) increase in the total dry deposition of NO y , and an enhancement of 1.4 Gg N (1.5 Gg N) in the total of dry and wet deposition of NO y over this region in August (February). These results suggest that the additional HONO sources aggravate regional-scale acid deposition, emphasizing the importance of the additional HONO sources in the NO y budget.(Citation: Li, Y., J. An, M. Kajino, J. Li, and Y. Qu, 2015: Impacts of additional HONO sources on concentrations and deposition of NO y in the Beijing-Tianjin-Hebei region of China. SOLA, 11, 36−42,

Exploring Possible Missing Sinks of Nitrate and Its Precursors in Current Air Quality Models —A Case Simulation in the Pearl River Delta, China, Using an Observation-Based Box Model

“…Compared with HONO, gaseous HNO 3 displayed the reverse pattern, with a daytime maximum of 5−6 ppbv. The daytime HONO at Kaiping was similar to summertime observations at suburban sites in other megacities in China (e.g., Beijing and Shanghai), but was slightly higher than those in summer and winter at European and US suburban sites (Li et al 2015;Michoud et al 2014). Gaseous HNO 3 at Kaiping was almost 3−4 times higher than levels reported in California and Mexico City where the diurnal maximum in spring and summer was usually 1 ppbv (Day et al 2009;Zheng et al 2008).…”

“…During the daytime on 31 th , the simulated HNO 3 /NO x ratio was four, while the observation was only ~1. Levels of HONO were significantly under estimated without an additional source (R2), which was previously reported by Li et al (2015). We selected uptake coefficients for R1 and R2 in which simulated HNO 3 and HONO were closest to the observations.…”

“…Recently, sporadic observations in China have suggested that the overestimation of gaseous nitric acid (HNO 3 ) in models might be the cause of the high nitrate levels in simulations. Li et al (2015) simulated summer HNO 3 in Beijing using WRF-Chem and predicted levels in the range 2−5 parts per billion by volume (ppbv), which was much higher than observations (0−1 ppbv). Similar results were also found in the northwestern Pacific, where simulated HNO 3 /NO x and peroxy acetyl nitrate (PAN)/NO x were found to be 2−3 times higher than observations during the Transport and Chemical Evolution over the Pacific (TRACE-P) campaign (Talbot et al 2003).…”

“…In the Pearl River Delta, this enhancement was 0.2−0.5 ppbv. This enhancement of HONO accounted for more than 90%−95% of simulated HONO in S4, which indicates that heterogeneous chemistry was the dominant source of HONO, rather than the gas chemistry (Li et al 2015). Among the heterogeneous reactions, R2 produced a more significant HONO enhancement than R1 (Fig.…”

“…Note that the observed daytime HONO was still underestimated using the suggested γ HONO , which is likely to be because unknown additional sources depending on NO 2 photolysis rates was not included in this study (Li et al 2015).…”