Sources and spatial distribution of PM2.5-bound polycyclic aromatic hydrocarbons in Zhengzhou in 2016

Li, Qiang; Jiang, Nan; Yu, Xue; Dong, Zhe; Duan, Shiguang; Zhang, Leishi; Zhang, Ruiqin

doi:10.1016/j.atmosres.2018.09.011

Cited by 44 publications

(10 citation statements)

References 61 publications

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“…Second, the hourly level of HONO abatement pathways, except OH + HONO, should be at least 0.22 ppbv h −1 (i.e., 3.36-1.59 ppbv (8 h) −1 ). This phenomenon may arise because the dry deposition on ground surfaces can be the main HONO removal pathway at night, which is similar to a previous study (Li et al, 2012).…”

Section: Homogeneous Reaction Of No and Ohsupporting

confidence: 85%

“…The HONO/NO 2 ratio is commonly used to estimate the formation of HONO in NO 2 transformation (Wang et al, 2013). Compared to HONO formation, NO 2 transformation is less affected by the migration of atmospheric air mass during atmospheric migration (Li et al, 2012). The HONO/NO 2 ratio in the CDs period began to increase after sunset and reached its peak at night.…”

Section: Temporal Variations Of Meteorological Parameters and Pollutantsmentioning

confidence: 99%

“…The dHONO/dt calculated from the measurements was small and evenly distributed at around zero (Li et al, 2012). P unknown is the production rate by an unknown daytime HONO source.…”

Section: Daytime Hono Budgetmentioning

confidence: 99%

“…For example, Hao et al (2006) reported that field measurement results, especially HONO/NO 2 and relative humidity (RH), have a significant correlation and proved that heterogeneous reactions are an important source of nighttime HONO. Although the specific chemical mechanisms of heterogeneous reactions remain unknown, the intensity of HONO formation by NO 2 can be expressed by the HONO conversion frequency (Alicke et al, 2002;Li et al, 2012). Su et al (2008a) revealed the importance of the q OH from HONO during daytime (09:00-15:00 local time or LT) and found that many unknown sources that are closely related to the solar radiation lead to HONO formation.…”

Section: Introductionmentioning

confidence: 99%

“…The homogeneous nucleation of NO 2 , H 2 O, and NH 3 is the HONO-formation pathway (Zhang and Tao, 2010). Meanwhile, HONO can deposit and react with amines to form nitrosamines (Li et al, 2012) for sinking. The method of budget analysis needs to include the HONO sources and sinks.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics, sources, and reactions of nitrous acid during winter at an urban site in the Central Plains Economic Region in China

et al. 2020

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Abstract. Nitrous acid (HONO) in the core city of the Central Plains Economic Region in China was measured using an ambient ion monitor from 9 to 31 January 2019. Measurement time intervals were classified into the following periods in accordance with the daily mean values of PM2.5: clean days (CDs), polluted days (PDs), and severely polluted days (SPDs). The HONO concentrations during CD, PD, and SPD periods were 1.2, 2.3, and 3.7 ppbv, respectively. The contributions of the homogeneous reaction, heterogeneous conversion, and direct emissions to HONO sources varied under different pollution levels. The mean values of the net HONO production of the homogeneous reaction (POH+NOnet) in CD, PD, and SPD periods were 0.13, 0.26, and 0.56 ppbv h−1, respectively. The average conversions of NO2 (CHONO) in CD, PD, and SPD periods were 0.72×10-2, 0.64×10-2, and 1.54×10-2 h−1, respectively, indicating that the heterogeneous conversion of NO2 was less important than the homogeneous reaction. Furthermore, the net production of the homogeneous reaction may have been the main factor in the increase of HONO under high-NOx conditions (i.e., when the concentration of NO was higher than that of NO2) at nighttime. Daytime HONO budget analysis showed that the mean values of the unknown source (Punknown) during CD, PD, and SPD periods were 0.26, 0.40, and 1.83 ppbv h−1, respectively. The values of POH+NOnet, CHONO, and Punknown in the SPDs period were comparatively larger than those in other periods, indicating that HONO participated in many reactions. The proportions of nighttime HONO sources also changed during the entire sampling period. Direct emissions and a heterogeneous reaction controlled HONO production in the first half of the night and provided a contribution that is larger than that of the homogeneous reaction. The proportion of homogenization gradually increased in the second half of the night due to the steady increase in NO concentrations. The hourly level of HONO abatement pathways, except for OH + HONO, was at least 0.22 ppbv h−1 in the SPDs period. The cumulative frequency distribution of the HONOemission∕HONO ratio (less than 20 %) was approximately 77 %, which suggested that direct emission was not important. The heterogeneous HONO production increased when the relative humidity (RH) increased, but it decreased when RH increased further. The average HONO∕NOx ratio (4.9 %) was more than twice the assumed globally averaged value (2.0 %).

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Section: Homogeneous Reaction Of No and Ohsupporting

confidence: 85%

Section: Temporal Variations Of Meteorological Parameters and Pollutantsmentioning

confidence: 99%

“…The dHONO/dt calculated from the measurements was small and evenly distributed at around zero (Li et al, 2012). P unknown is the production rate by an unknown daytime HONO source.…”

Section: Daytime Hono Budgetmentioning

confidence: 99%