TY - JOUR
T1 - New insight into the spatiotemporal variability and source apportionments of C1-C4 alkyl nitrates in Hong Kong
AU - Ling, Zhenhao
AU - Guo, Hai
AU - Jane Simpson, Isobel
AU - Maria Saunders, Sandra
AU - Ho Man Lam, Sean
AU - Lyu, Xiaopu
AU - Ray Blake, Donald
N1 - Funding Information:
This project was supported by the Research Grants Council of the Hong Kong Special Administrative Region via grants PolyU5154/13E, PolyU152052/14E and CRF/C5022-14G. This study was partly supported by the internal grants of the Hong Kong Polytechnic University (4-BCAV and 1-ZVCX) and the National Natural Science Foundation of China (No. 41405112 and 41275122). The challenging but ultimately very helpful comments of the anonymous reviewers are greatly appreciated.
Publisher Copyright:
© Author(s) 2016.
PY - 2016/7
Y1 - 2016/7
N2 - C1-C4 alkyl nitrates (RONO2/were measured concurrently at a mountain site, Tai Mo Shan (TMS), and an urban site, Tsuen Wan (TW), at the base of the same mountain in Hong Kong from September to November 2010. Although the levels of parent hydrocarbons were much lower at TMS (p <0.05), similar alkyl nitrate levels were found at both sites regardless of the elevation difference, suggesting various source contributions of alkyl nitrates at the two sites. Prior to using a positive matrix factorization (PMF) model, the data at TW were divided into "meso" and "non-meso" scenarios for the investigation of source apportionments with the influence of mesoscale circulation and regional transport, respectively. Secondary formation was the prominent contributor of alkyl nitrates in the meso scenario (60±2 %, 60.2±1.2 pptv), followed by biomass burning and oceanic emissions, while biomass burning and secondary formation made comparable contributions to alkyl nitrates in the nonmeso scenario, highlighting the strong emissions of biomass burning in the inland Pearl River delta (PRD) region. In contrast to TW, the alkyl nitrate levels measured at TMS mainly resulted from the photooxidation of the parent hydrocarbons at TW during mesoscale circulation, i.e., valley breezes, corresponding to 52-86% of the alkyl nitrate levels at TMS. Furthermore, regional transport from the inland PRD region made significant contributions to the levels of alkyl nitrates (∼58-82 %) at TMS in the non-meso scenario, resulting in similar levels of alkyl nitrates observed at the two sites. The simulation of secondary formation pathways using a photochemical box model found that the reaction of alkyl peroxy radicals (RO2/with nitric oxide (NO) dominated the formation of RONO2 at both sites, and the formation of alkyl nitrates contributed negatively to O3 production, with average reduction rates of 4.1 and 4.7 pptv pptv-1 at TMS and TW, respectively.
AB - C1-C4 alkyl nitrates (RONO2/were measured concurrently at a mountain site, Tai Mo Shan (TMS), and an urban site, Tsuen Wan (TW), at the base of the same mountain in Hong Kong from September to November 2010. Although the levels of parent hydrocarbons were much lower at TMS (p <0.05), similar alkyl nitrate levels were found at both sites regardless of the elevation difference, suggesting various source contributions of alkyl nitrates at the two sites. Prior to using a positive matrix factorization (PMF) model, the data at TW were divided into "meso" and "non-meso" scenarios for the investigation of source apportionments with the influence of mesoscale circulation and regional transport, respectively. Secondary formation was the prominent contributor of alkyl nitrates in the meso scenario (60±2 %, 60.2±1.2 pptv), followed by biomass burning and oceanic emissions, while biomass burning and secondary formation made comparable contributions to alkyl nitrates in the nonmeso scenario, highlighting the strong emissions of biomass burning in the inland Pearl River delta (PRD) region. In contrast to TW, the alkyl nitrate levels measured at TMS mainly resulted from the photooxidation of the parent hydrocarbons at TW during mesoscale circulation, i.e., valley breezes, corresponding to 52-86% of the alkyl nitrate levels at TMS. Furthermore, regional transport from the inland PRD region made significant contributions to the levels of alkyl nitrates (∼58-82 %) at TMS in the non-meso scenario, resulting in similar levels of alkyl nitrates observed at the two sites. The simulation of secondary formation pathways using a photochemical box model found that the reaction of alkyl peroxy radicals (RO2/with nitric oxide (NO) dominated the formation of RONO2 at both sites, and the formation of alkyl nitrates contributed negatively to O3 production, with average reduction rates of 4.1 and 4.7 pptv pptv-1 at TMS and TW, respectively.
UR - http://www.scopus.com/inward/record.url?scp=84978159497&partnerID=8YFLogxK
U2 - 10.5194/acp-16-8141-2016
DO - 10.5194/acp-16-8141-2016
M3 - Journal article
AN - SCOPUS:84978159497
SN - 1680-7316
VL - 16
SP - 8141
EP - 8156
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 13
ER -
