Evidence of Reactive Aromatics As a Major Source of Peroxy Acetyl Nitrate over China

Abstract

We analyze the observations of near-surface peroxy acetyl nitrate (PAN) and its precursors in Beijing, China in August of 2007. The levels of PAN are remarkably high (up to 14 ppbv), surpassing those measured over other urban regions in recent years. Analyses employing a 1-D version of a chemical transport model (Regional chEmical and trAnsport Model, REAM) indicate that aromatic non-methane hydrocarbons (NMHCs) are the dominant (55-75%) PAN source. The major oxidation product of aromatics that produces acetyl peroxy radicals is methylglyoxal (MGLY). PAN and O(3) in the observations are correlated at daytime; aromatic NMHCs appear to play an important role in O(3) photochemistry. Previous NMHC measurements indicate the presence of reactive aromatics at high levels over broad polluted regions of China. Aromatics are often ignored in global and (to a lesser degree) regional 3D photochemical transport models; their emissions over China as well as photochemistry are quite uncertain. Our findings suggest that critical assessments of aromatics emissions and chemistry (such as the yields of MGLY) are necessary to understand and assess ozone photochemistry and regional pollution export in China.

Seasonal and diurnal variations of atmospheric peroxyacetyl nitrate, peroxypropionyl nitrate, and carbon tetrachloride in Beijing

“…Peroxyacetyl radical, as an important component of peroxy radicals, also participates in O 3 production, and generates PAN via its reaction with NO 2 in the atmosphere. Therefore, a positive correlation between PAN and O 3 is expected and has been reported in the summer and autumn daytime in Beijing (Liu et al, 2010;Wang and Zhang, 2007; 2009) and in other urban areas, i.e., Porto Alegre, Brazil (Grosjean et al, 2002) and Munich .…”

“…Due to the particular importance of PANs on atmospheric chemistry, a great number of PANs measurements have been conducted intensively in developed countries, including the urban regions (Grosjean et al, 2001;Marley et al, 2007;Roberts et al, 1995) and remote area (Hartsell et al, 1994;Roberts et al, 2004;Singh et al, 1990Singh et al, , 1992Williams and Grosjean, 1991). However, only few researches involving with PANs are implemented in developing countries of Asia (Lee et al, 2008;Watanabe et al, 1998;Zhang and Tang, 1994;Wang et al, 2010;Zhang et al, 2009).…”

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

“…Figure 1f showed that PAN observations were underestimated by more than 80% in both Cases R and E. It is likely because the model underestimated the concentrations of acetaldehyde (CH 3 CHO) and methylglyoxal (MGLY, CH 2 CHC(O) CH 3 ) (Fig. S2), which were found as the dominant PAN sources in urban Beijing (Liu et al 2010). The additional HONO sources also increased daytime concentrations of CH 3 CHO, MGLY and PAN.…”

“…For winter period, only 24-h averages of HONO, NO 2 and NO 3 − were obtained. Details were given in Liu et al (2010) and Spataro et al (2013).…”

Theoretical study of the reaction mechanism and kinetics of low-molecular-weight atmospheric aldehydes (C1–C4) with NO2

“…Photochemical pollution has become an important air quality issue in China due to increased emissions of volatile organic compounds (VOCs) and nitrogen oxides (NO x ) driven by the rapid economic growth (Liu et al, 2010). Aldehydes, an important class of VOCs, are directly discharged into the troposphere from biogenic and anthropogenic sources (Zhang et al, 2006b), and have received scientific and regulatory attention due to their potential adverse health effects on humans as well as their important role in atmospheric photochemical reactions (Grosjean, 1982;Hoekman, 1992;Nondek et al, 1992;Zhou and Mopper, 1990).…”