Evidence of reactive aromatics as a major source of peroxy acetyl nitrate over China.
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.
Liu
Zhen
Z
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA. zhen.liu@eas.gatech.edu
Wang
Yuhang
Y
Gu
Dasa
D
Zhao
Chun
C
Huey
L Gregory
LG
Stickel
Robert
R
Liao
Jin
J
Shao
Min
M
Zhu
Tong
T
Zeng
Limin
L
Liu
Shaw-Chen
SC
Chang
Chih-Chung
CC
Amoroso
Antonio
A
Costabile
Francesca
F
D002681:China; D006841:Hydrocarbons, Aromatic / Q000032:analysis*; D008956:Models, Chemical; D009038:Motion; D010463:Peracetic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D013997:Time Factors
D006841:Hydrocarbons, Aromatic; D010463:Peracetic Acid; C004185:peroxyacetyl nitrate