TY - JOUR
T1 - Re-examination of C1-C5 alkyl nitrates in Hong Kong using an observation-based model
AU - Lyu, X. P.
AU - Ling, Z. H.
AU - Guo, H.
AU - Saunders, S. M.
AU - Lam, S. H. M.
AU - Wang, N.
AU - Wang, Y.
AU - Liu, M.
AU - Wang, T.
N1 - Funding Information:
"This study was supported by the Research Grants Council of the Hong Kong Special Administrative Region via grants PolyU5154/13E and PolyU152052/14E, and the Hong Kong Polytechnic University Ph.D. scholarships (project #RTUP). This study is partly supported by the Public Policy Research Funding Scheme (2013.A6.012.13A) and the National Natural Science Foundation of China (No. 41275122). We appreciate Prof. Blake''s group at the University of California at Irvine for the chemical analysis of the whole air VOC samples." The authors would like to apologise for any inconvenience caused.
Funding Information:
This study was supported by the Research Grants Council of the Hong Kong Special Administrative Region via grants PolyU5154/13E and PolyU152052/14E , and the Hong Kong Polytechnic University Ph.D. scholarships (project #RTUP). This study is partly supported by the Public Policy Research Funding Scheme ( 2013.A6.012.13A ) and the National Natural Science Foundation of China (No. 41275122 ). We appreciate Prof. Blake's group at the University of California at Irvine for the chemical analysis of the whole air VOC samples.
Publisher Copyright:
© 2015 Elsevier Ltd.
PY - 2015/11
Y1 - 2015/11
N2 - The photochemical formation of alkyl nitrates (RONO2) and their impact on ozone (O3) formation were investigated using a Photochemical Box Model incorporating the Master Chemical Mechanism (PBM-MCM). The model was constrained with field measurement data collected on selected O3 episode days at Tai O, a rural-coastal site in southwestern Hong Kong, from August 2001-December 2002. The in-situ observations showed that the sum of C1-C5 RONO2 varied from 30.7 ± 14.8 pptv in spring to 120.7 ± 10.4 pptv in autumn, of which 2-butyl nitrate dominated with the highest average concentration of 30.8 ± 2.6 pptv. Model simulations indicated that the pathway of CH3O reacting with NO2, proposed in our previous study, made minor contributions (11.3 ± 0.7%) to methyl nitrate formation. Indeed, 51.8 ± 3.1% and 36.5 ± 6.3% of the methyl nitrate was attributed to the reaction of CH3O2+NO and to oceanic emissions/biomass burning, respectively. For the C2-C5 alkyl nitrates, the contribution of photochemical formation increased with increasing carbon number, ranging from 64.4 ± 4.0% for ethyl nitrate (EtONO2) to 72.6 ± 4.2% for 2-pentyl nitrate (2-PenONO2), while the contribution of oceanic emissions/biomass burning decreased from 35.1 ± 6.5% for EtONO2 to 26.8 ± 6.8% for 2-PenONO2. Model simulations of photochemical O3 levels influenced by RONO2 chemistry showed that the formation of methyl-, ethyl-, i-propyl-, n-propyl-, 2-butyl-, 2-pentyl-, and 3-pentyl-nitrates led to O3 reduction of 0.05 ± 0.03, 0.05 ± 0.03, 0.06 ± 0.02, 0.02 ± 0.02, 0.18 ± 0.04, 0.09 ± 0.02 and 0.06 ± 0.02 ppbv, respectively, with an average reduction rate of 11.0 ± 3.2 ppbv O3 per 1 ppbv RONO2 formation. The C1-C5 RONO2 constituted 18.6 ± 1.9% of the entire RONO2, and had a nitrogen reserve of 4.1 ± 0.2%, implying their potential influence on O3 production in downwind areas.
AB - The photochemical formation of alkyl nitrates (RONO2) and their impact on ozone (O3) formation were investigated using a Photochemical Box Model incorporating the Master Chemical Mechanism (PBM-MCM). The model was constrained with field measurement data collected on selected O3 episode days at Tai O, a rural-coastal site in southwestern Hong Kong, from August 2001-December 2002. The in-situ observations showed that the sum of C1-C5 RONO2 varied from 30.7 ± 14.8 pptv in spring to 120.7 ± 10.4 pptv in autumn, of which 2-butyl nitrate dominated with the highest average concentration of 30.8 ± 2.6 pptv. Model simulations indicated that the pathway of CH3O reacting with NO2, proposed in our previous study, made minor contributions (11.3 ± 0.7%) to methyl nitrate formation. Indeed, 51.8 ± 3.1% and 36.5 ± 6.3% of the methyl nitrate was attributed to the reaction of CH3O2+NO and to oceanic emissions/biomass burning, respectively. For the C2-C5 alkyl nitrates, the contribution of photochemical formation increased with increasing carbon number, ranging from 64.4 ± 4.0% for ethyl nitrate (EtONO2) to 72.6 ± 4.2% for 2-pentyl nitrate (2-PenONO2), while the contribution of oceanic emissions/biomass burning decreased from 35.1 ± 6.5% for EtONO2 to 26.8 ± 6.8% for 2-PenONO2. Model simulations of photochemical O3 levels influenced by RONO2 chemistry showed that the formation of methyl-, ethyl-, i-propyl-, n-propyl-, 2-butyl-, 2-pentyl-, and 3-pentyl-nitrates led to O3 reduction of 0.05 ± 0.03, 0.05 ± 0.03, 0.06 ± 0.02, 0.02 ± 0.02, 0.18 ± 0.04, 0.09 ± 0.02 and 0.06 ± 0.02 ppbv, respectively, with an average reduction rate of 11.0 ± 3.2 ppbv O3 per 1 ppbv RONO2 formation. The C1-C5 RONO2 constituted 18.6 ± 1.9% of the entire RONO2, and had a nitrogen reserve of 4.1 ± 0.2%, implying their potential influence on O3 production in downwind areas.
KW - Alkyl nitrate
KW - Field observation
KW - O3 production
KW - PBM-MCM model
KW - Photochemical formation
UR - http://www.scopus.com/inward/record.url?scp=84940770291&partnerID=8YFLogxK
U2 - 10.1016/j.atmosenv.2015.08.083
DO - 10.1016/j.atmosenv.2015.08.083
M3 - Journal article
AN - SCOPUS:84940770291
SN - 1352-2310
VL - 120
SP - 28
EP - 37
JO - Atmospheric Environment
JF - Atmospheric Environment
ER -