| Title: | Atmospheric fate of peroxyacetyl nitrate in suburban Hong Kong and its impact on local ozone pollution |
| Author(s): | Zeng L; Fan GJ; Lyu X; Guo H; Wang JL; Yao D; |
| Address: | "Air Quality Studies, Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong. Department of Chemistry, National Central University, Taiwan. Air Quality Studies, Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong. Electronic address: ceguohai@polyu.edu.hk" |
| DOI: | 10.1016/j.envpol.2019.06.004 |
| ISSN/ISBN: | 1873-6424 (Electronic) 0269-7491 (Linking) |
| Abstract: | "Peroxyacetyl nitrate (PAN) is an important reservoir of atmospheric nitrogen, modulating reactive nitrogen cycle and ozone (O(3)) formation. To understand the origins of PAN, a field measurement was conducted at Tung Chung site (TC) in suburban Hong Kong from October to November 2016. The average level of PAN was 0.63?ª++/-?ª+0.05?ª+ppbv, with a maximum of 7.30?ª+ppbv. Higher PAN/O(3) ratio (0.043-0.058) was captured on episodes, i.e. when hourly maximum O(3) exceeded 80?ª+ppbv, than on non-episodes (0.01), since O(3) production was less efficient than PAN when there was an elevation of precursors (i.e. volatile organic compounds (VOCs) and nitrogen oxide (NO(x))). Model simulations revealed that oxidations of acetaldehyde (65.3?ª++/-?ª+2.3%), methylglyoxal (MGLY, 12.7?ª++/-?ª+1.2%) and other oxygenated VOCs (OVOCs) (8.0?ª++/-?ª+0.6%), and radical cycling (12.2?ª++/-?ª+0.8%) were the major production pathways of peroxyacetyl (PA) radical, while local PAN formation was controlled by both VOCs and nitrogen dioxide (NO(2)). Among all VOC species, carbonyls made the highest contribution (59%) to PAN formation, followed by aromatics (26%) and biogenic VOCs (BVOCs) (10%) through direct oxidation/decomposition. Besides, active VOCs (i.e. carbonyls, aromatics, BVOCs and alkenes/alkynes) could stimulate hydroxyl (OH) production, thus indirectly facilitating the PAN formation. Apart from primary emissions, carbonyls were also generated from oxidation of first-generation precursors, i.e., hydrocarbons, of which xylenes contributed the most to PAN production. Furthermore, PAN formation suppressed local O(3) formation at a rate of 2.84?ª+ppbv/ppbv, when NO(2), OH and hydroperoxy (HO(2)) levels decreased and nitrogen monoxide (NO) value enhanced. Namely, O(3) was reduced by 2.84?ª+ppbv per ppbv PAN formation. Net O(3) production rate was weakened ( approximately 36%) due to PAN photochemistry, so as each individual production and loss pathway. The findings advanced our knowledge of atmospheric PAN and its impact on O(3) production" |
| Keywords: | Acetaldehyde/chemistry Air Pollutants/*analysis *Environmental Monitoring Environmental Pollution/*analysis Hong Kong Hydrocarbons/analysis Hydroxyl Radical/analysis Nitrogen Oxides/analysis Oxidation-Reduction Ozone/*analysis Peracetic Acid/*analogs & de; |
| Notes: | "MedlineZeng, Lewei Fan, Gang-Jie Lyu, Xiaopu Guo, Hai Wang, Jia-Lin Yao, Dawen eng England 2019/06/23 Environ Pollut. 2019 Sep; 252(Pt B):1910-1919. doi: 10.1016/j.envpol.2019.06.004. Epub 2019 Jun 6" |
