Unexpected Fast Monoterpene Oxidation In Eastern China

2021 ◽  
Author(s):  
Haichao Wang
Keyword(s):  
Eastern China ◽  
Field Measurements ◽  
Ozone Production ◽  
Nitrate Radical ◽  
Peroxy Radicals ◽  
Ozone Pollution ◽  
Volatile Organic ◽  
Secondary Aerosols ◽  
Photochemical Ozone

<p>Monoterpene plays an important role in the formation of secondary aerosols and ozone in the troposphere. However, the field characterization of monoterpene chemistry in ozone pollution is still very sparse. Here we report fast daytime oxidation of monoterpene by hydroxyl radical, nitrate radical and ozone based on field measurements in Eastern China. We find fast monoterpene oxidation produces peroxy radicals efficiently and enhances the photochemical ozone production largely with an additional 8.6 ppb of ozone production per day on average (14%), whose effect was even more important than that of isoprene chemistry in the analyzed dataset. We propose that the reduction of anthropogenic volatile organic compounds should be much more stringent in the presence of high monoterpenes to alleviating ozone pollution.</p>

scholarly journals Characterization of ozone production in San Antonio, Texas, using measurements of total peroxy radicals

2019 ◽  
Vol 19 (5) ◽  
pp. 2845-2860 ◽  
Author(s):  
Daniel C. Anderson ◽  
Jessica Pavelec ◽  
Conner Daube ◽  
Scott C. Herndon ◽  
Walter B. Knighton ◽  
...  
Keyword(s):  
San Antonio ◽  
Peroxy Radical ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Entire Region ◽  
Volatile Organic ◽  
In Situ Observations ◽  
Study Sites

Abstract. Observations of total peroxy radical concentrations ([XO2] ≡ [RO2] + [HO2]) made by the Ethane CHemical AMPlifier (ECHAMP) and concomitant observations of additional trace gases made on board the Aerodyne Mobile Laboratory (AML) during May 2017 were used to characterize ozone production at three sites in the San Antonio, Texas, region. Median daytime [O3] was 48 ppbv at the site downwind of central San Antonio. Higher concentrations of NO and XO2 at the downwind site also led to median daytime ozone production rates (P(O3)) of 4.2 ppbv h−1, a factor of 2 higher than at the two upwind sites. The 95th percentile of P(O3) at the upwind site was 15.1 ppbv h−1, significantly lower than values observed in Houston. In situ observations, as well as satellite retrievals of HCHO and NO2, suggest that the region was predominantly NOx-limited. Only approximately 20 % of observations were in the VOC-limited regime, predominantly before 11:00 EST, when ozone production was low. Biogenic volatile organic compounds (VOCs) comprised 55 % of total OH reactivity at the downwind site, with alkanes and non-biogenic alkenes responsible for less than 10 % of total OH reactivity in the afternoon, when ozone production was highest. To control ozone formation rates at the three study sites effectively, policy efforts should be directed at reducing NOx emissions. Observations in the urban center of San Antonio are needed to determine whether this policy is true for the entire region.

scholarly journals Characterization of Ozone Production in San Antonio, Texas Using Observations of Total Peroxy Radicals

2018 ◽  
Author(s):  
Daniel C. Anderson ◽  
Jessica Pavelec ◽  
Conner Daube ◽  
Scott C. Herndon ◽  
W. Berk Knighton ◽  
...  
Keyword(s):  
San Antonio ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Urban Center ◽  
Entire Region ◽  
Volatile Organic ◽  
In Situ Observations ◽  
Study Sites

Abstract. Observations of total peroxy radicals (XO2 = RO2 + HO2) made by the Ethane CHemical AMPlifier (ECHAMP) and concomitant observations of additional trace gases made onboard the Aerodyne Mobile Laboratory (AML) during May 2017 were used to characterize ozone production at three sites in the San Antonio, Texas region. Median daytime [O3] was 48 ppbv at the site downwind of central San Antonio. Higher concentrations of NO and XO2 at the downwind site also led to median daytime ozone production rates (P(O3)) of 4.2 ppbv hr−1, a factor of two higher than at the two upwind sites. The 95th percentile of P(O3) at the upwind site was 15.1 ppbv hr−1, significantly lower than values observed in Houston. In situ observations, as well as satellite retrievals of HCHO and NO3, suggest that the region is NOx limited for times after approximately 09:00 local time, before which ozone production is VOC-limited. Biogenic volatile organic compounds (VOC) comprised 55 % of total OH reactivity at the downwind site, with alkanes and non-biogenic alkenes responsible for less than 10 % of total OH reactivity in the afternoon, when ozone production was highest. To control ozone formation rates at the three study sites effectively, policy efforts should be directed at reducing NOx emissions. Observations in the urban center of San Antonio are needed to determine whether this policy is true for the entire region.

scholarly journals Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities

2021 ◽  
Author(s):  
Leigh Crilley ◽  
Yashar Iranpour ◽  
Cora J. Young
Keyword(s):  
Atmospheric Chemistry ◽  
Field Measurements ◽  
Air Pollutant ◽  
Mitigation Strategies ◽  
Ozone Production ◽  
Linear Relationships ◽  
Regional Sources ◽  
Volatile Organic ◽  
Emission Changes ◽  
Indian Cities

To accurately quantify impact of short-term interventions (such as COVID-19 lockdown) on air pollutant levels, meteorology and atmospheric chemistry need to be considered in addition to emission changes. We demonstrate that regional sources have a significant influence on PM<sub>2.5 </sub>levels in Delhi and Hyderabad due to the small reduction calculated post-lockdown after weather-normalization, indicating that future PM<sub>2.5</sub> mitigation strategies should focus on national-scale, as well as local sources. Furthermore, we demonstrate with field measurements that ozone production in Delhi is likely volatile organic compound (VOC)-limited, in agreement with previous modelling predictions, indicating that ozone mitigation should focus on dominant VOC sources. This work highlights the complexity in developing mitigation strategies for air pollution due to its non-linear relationships with emissions, chemistry and meteorology.

scholarly journals Ozone seasonal evolution and photochemical production regime in polluted troposphere in eastern China derived from high resolution FTS observations

2017 ◽  
Author(s):  
Youwen Sun ◽  
Cheng Liu ◽  
Mathias Palm ◽  
Corinne Vigouroux ◽  
Qihou Hu ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Meteorological Data ◽  
Eastern China ◽  
Ozone Production ◽  
Ozone Pollution ◽  
Seasonal Evolution ◽  
Photochemical Production ◽  
Production Regime ◽  
Autumn And Winter ◽  
Ozone Levels

Abstract. A precise knowledge of ozone seasonal evolution and photochemical production regime in polluted troposphere in China has important policy implications for ozone pollution controls especially in megacities where ozone pollution is common throughout the year. In this study, we used tropospheric ozone, CO and HCHO columns derived from high resolution Fourier transform infrared spectrometry (FTS) in Hefei, China, tropospheric NO2 columns deduced from overpass Ozone Monitoring Instrument (OMI), surface meteorological data, and a back trajectory cluster analysis technique to investigate ozone seasonal evolution and photochemical production regime in eastern China from 2014–2017. A pronounced seasonal cycle for tropospheric ozone is captured by FTS, where high levels of tropospheric ozone occurs in spring and summer, and low levels of tropospheric ozone occurs in autumn and winter. Day-to-day variations in spring and summer are in most cases larger than those in autumn and winter. At the same time, it shows that the tropospheric ozone roughly increases over time at the first half year and reaches the maximum in June, and then it decreases over time at the second half year. Tropospheric ozone columns in June are, on average, 0.5×1018 molecules*cm−2 (47.6 %) higher than those in December which has a mean value of 1.05×1018 molecules*cm−2. The OMI time series shows similar behaviour. The measured features can basically be reproduced by GEOS-Chem and WRF-Chem data but with slight shifts in the timing of the seasonal maximum. Back trajectories analysis shows that: air pollutions in megacities in central-southern China, northwest China, and the key pollution area, i.e., Yangtze River Delta area in eastern China, dominates the contributions to the observed tropospheric ozone levels, while the contributions from the other two key pollution areas, i.e., Beijing-Tianjin-Hebei in north China and Pearl River Delta in south China, are very small; Air masses generated from polluted areas have more transportations to the observed area in spring and summer than in autumn and winter, and hence have more contributions to the observed tropospheric ozone levels. Correlations between tropospheric ozone and meteorological data disclosed that spring and summer is more favorable to photochemical ozone production than in autumn and winter. Finally, the HCHO/NO2 ratio is used as a proxy to investigate the chemical sensitivity of ozone production (PO3). The results show that the PO3 is mainly NOx limited in summer, while it is mainly VOC or mix VOC-NOx limited in winter. Statistics show that NOx limited, mix VOC-NOx limited, and VOC limited PO3 accounts for 60.1 %, 28.7 %, and 11 %, respectively.

scholarly journals An MCM modeling study of nitryl chloride (ClNO<sub>2</sub>) impacts on oxidation, ozone production and nitrogen oxide partitioning in polluted continental outflow

2014 ◽  
Vol 14 (8) ◽  
pp. 3789-3800 ◽  
Author(s):  
T. P. Riedel ◽  
G. M. Wolfe ◽  
K. T. Danas ◽  
J. B. Gilman ◽  
W. C. Kuster ◽  
...  
Keyword(s):  
Nitrogen Oxide ◽  
Organic Compounds ◽  
Field Measurements ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Model Framework ◽  
Dinitrogen Pentoxide ◽  
Nitryl Chloride ◽  
Hydrogen Oxide

Abstract. Nitryl chloride (ClNO2) is produced at night by reactions of dinitrogen pentoxide (N2O5) on chloride containing surfaces. ClNO2 is photolyzed during the morning hours after sunrise to liberate highly reactive chlorine atoms (Cl·). This chemistry takes place primarily in polluted environments where the concentrations of N2O5 precursors (nitrogen oxide radicals and ozone) are high, though it likely occurs in remote regions at lower intensities. Recent field measurements have illustrated the potential importance of ClNO2 as a daytime Cl· source and a nighttime NOx reservoir. However, the fate of the Cl· and the overall impact of ClNO2 on regional photochemistry remain poorly constrained by measurements and models. To this end, we have incorporated ClNO2 production, photolysis, and subsequent Cl· reactions into an existing master chemical mechanism (MCM version 3.2) box model framework using observational constraints from the CalNex 2010 field study. Cl· reactions with a set of alkenes and alcohols, and the simplified multiphase chemistry of N2O5, ClNO2, HOCl, ClONO2, and Cl2, none of which are currently part of the MCM, have been added to the mechanism. The presence of ClNO2 produces significant changes to oxidants, ozone, and nitrogen oxide partitioning, relative to model runs excluding ClNO2 formation. From a nighttime maximum of 1.5 ppbv ClNO2, the daytime maximum Cl· concentration reaches 1 × 105 atoms cm−3 at 07:00 model time, reacting mostly with a large suite of volatile organic compounds (VOC) to produce 2.2 times more organic peroxy radicals in the morning than in the absence of ClNO2. In the presence of several ppbv of nitrogen oxide radicals (NOx = NO + NO2), these perturbations lead to similar enhancements in hydrogen oxide radicals (HOx = OH + HO2). Neglecting contributions from HONO, the total integrated daytime radical source is 17% larger when including ClNO2, which leads to a similar enhancement in integrated ozone production of 15%. Detectable levels (tens of pptv) of chlorine containing organic compounds are predicted to form as a result of Cl· addition to alkenes, which may be useful in identifying times of active Cl· chemistry.

scholarly journals Rates and regimes of photochemical ozone production over Central East China in June 2006: a box model analysis using comprehensive measurements of ozone precursors

2009 ◽  
Vol 9 (3) ◽  
pp. 12965-12997 ◽  
Author(s):  
Y. Kanaya ◽  
P. Pochanart ◽  
Y. Liu ◽  
J. Li ◽  
H. Tanimoto ◽  
...  
Keyword(s):  
Production Rate ◽  
Box Model ◽  
Ozone Production ◽  
East China ◽  
Ozone Concentrations ◽  
Volatile Organic ◽  
Upward Transport ◽  
Photochemical Ozone ◽  
Model Approach

Abstract. An observation-based box model approach was undertaken to estimate concentrations of OH, HO2, and RO2 radicals and the net photochemical production rate of ozone at the top of Mount Tai, located in the middle of Central East China, in June 2006. The model calculation was constrained by the measurements of O3, H2O, CO, NO, NO2, hydrocarbon, HCHO, and CH3CHO concentrations, and temperature and J values. The net production rate of ozone was estimated to be 6.4 ppb h−1 as a 6-h average (09:00–15:00 CST), suggesting 58 ppb of ozone is produced in one day. Thus the daytime buildup of ozone recorded at the mountain top as 23 ppb on average is likely affected by in situ photochemistry as well as by the upward transport of polluted air mass in the daytime. On days with high ozone concentrations (hourly values exceeding 100 ppb at least once), in situ photochemistry was more active than it was on low ozone days, suggesting that in situ photochemistry is an important factor controlling ozone concentrations. Sensitivity model runs for which different NOx and hydrocarbon concentrations were assumed suggested that the ozone production occurred normally under NOx-limited conditions, with some exceptional periods (under volatile-organic-compound-limited conditions) in which there was fresh pollution. We also examined the possible influence of the heterogeneous loss of gaseous HO2 radicals in contact with aerosol particle surfaces on the rate and regimes of ozone production.

scholarly journals Suppression of new particle formation from monoterpene oxidation by NO<sub>x</sub>

2014 ◽  
Vol 14 (6) ◽  
pp. 2789-2804 ◽  
Author(s):  
J. Wildt ◽  
T. F. Mentel ◽  
A. Kiendler-Scharr ◽  
T. Hoffmann ◽  
S. Andres ◽  
...  
Keyword(s):  
Nitrogen Monoxide ◽  
Peroxy Radical ◽  
Particle Formation ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
New Particle Formation ◽  
Laboratory Setup ◽  
Plant Volatile ◽  
Photochemical Ozone ◽  
The Impact

Abstract. The impact of nitrogen oxides (NOx = NO + NO2) on new particle formation (NPF) and on photochemical ozone production from real plant volatile organic compound (BVOC) emissions was studied in a laboratory setup. At high NOx conditions ([BVOC] / [NOx] < 7, [NOx] > 23 ppb) new particle formation was suppressed. Instead, photochemical ozone formation was observed resulting in higher hydroxyl radical (OH) and lower nitrogen monoxide (NO) concentrations. When [NO] was reduced back to levels below 1 ppb by OH reactions, NPF was observed. Adding high amounts of NOx caused NPF to be slowed by orders of magnitude compared to analogous experiments at low NOx conditions ([NOx] ~300 ppt), although OH concentrations were higher. Varying NO2 photolysis enabled showing that NO was responsible for suppression of NPF. This suggests that peroxy radicals are involved in NPF. The rates of NPF and photochemical ozone production were related by power law dependence with an exponent approaching −2. This exponent indicated that the overall peroxy radical concentration must have been similar when NPF occurred. Thus, permutation reactions of first-generation peroxy radicals cannot be the rate limiting step in NPF from monoterpene oxidation. It was concluded that permutation reactions of higher generation peroxy-radical-like intermediates limit the rate of new particle formation. In contrast to the strong effects on the particle numbers, the formation of particle mass was substantially less sensitive to NOx concentrations. If at all, yields were reduced by about an order of magnitude only at very high NOx concentrations.

scholarly journals <i>α</i>-Pinene Nitrates: synthesis, yields and atmospheric chemistry

2011 ◽  
Vol 11 (2) ◽  
pp. 6845-6874
Author(s):  
S. X. Ma ◽  
J. D. Rindelaub ◽  
K. M. McAvey ◽  
P. D. Gagare ◽  
B. A. Nault ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Organic Aerosol ◽  
Reaction Chamber ◽  
Oxidation Products ◽  
Ozone Production ◽  
Organic Nitrate ◽  
Peroxy Radicals ◽  
Nitrate Precursor ◽  
Volatile Organic ◽  
Major Oxidation

Abstract. The biogenic volatile organic compound α-pinene is one of the dominant monoterpenes emitted to the Earth's atmosphere at an estimated rate of ~50 Tg yr−1. Its atmospheric oxidation products in the presence of NO can lead to ozone production, as well as production of secondary organic aerosol (SOA). The major oxidation pathway of α-pinene is reaction with OH, which in the presence of NO can form either α-pinene nitrates or convert NO to NO2, which can photolyze to form ozone. In this work, we successfully synthesized four α-pinene hydroxy nitrates through three different routes, and have identified the 4 individual isomers in α-pinene/OH/NO reaction chamber experiments. From the experiments, we determined their individual production yields, estimated the total RONO2 yield, and calculated the relative branching ratios of the nitrate precursor peroxy radicals (RO2). The combined yield of the four α-pinene nitrates was found to be 13.0 (±0.7) % at atmospheric pressure and 296 K, and the total organic nitrate yield was estimated to be 0.19 (+0.10/−0.06). We also determined the OH rate constants for two of the isomers, and have calculated their overall atmospheric lifetimes, which range between 22 and 38 h.

scholarly journals Rates and regimes of photochemical ozone production over Central East China in June 2006: a box model analysis using comprehensive measurements of ozone precursors

2009 ◽  
Vol 9 (20) ◽  
pp. 7711-7723 ◽  
Author(s):  
Y. Kanaya ◽  
P. Pochanart ◽  
Y. Liu ◽  
J. Li ◽  
H. Tanimoto ◽  
...  
Keyword(s):  
Production Rate ◽  
Box Model ◽  
Ozone Production ◽  
East China ◽  
Ozone Concentrations ◽  
Volatile Organic ◽  
Upward Transport ◽  
Photochemical Ozone ◽  
Model Approach

Abstract. An observation-based box model approach was undertaken to estimate concentrations of OH, HO2, and RO2 radicals and the net photochemical production rate of ozone at the top of Mount Tai, located in the middle of Central East China, in June 2006. The model calculation was constrained by the measurements of O3, H2O, CO, NO, NO2, hydrocarbon, HCHO, and CH3CHO concentrations, and temperature and J values. The net production rate of ozone was estimated to be 6.4 ppb h−1 as a 6-h average (09:00–15:00 CST), suggesting 58±37 ppb of ozone is produced in one day. Thus the daytime buildup of ozone recorded at the mountain top as ~23 ppb on average is likely affected by in situ photochemistry as well as by the upward transport of polluted air mass in the daytime. On days with high ozone concentrations (hourly values exceeding 100 ppb at least once), in situ photochemistry was more active than it was on low ozone days, suggesting that in situ photochemistry is an important factor controlling ozone concentrations. Sensitivity model runs for which different NOx and hydrocarbon concentrations were assumed suggested that the ozone production occurred normally under NOx-limited conditions, with some exceptional periods (under volatile-organic-compound-limited conditions) in which there was fresh pollution. We also examined the possible influence of the heterogeneous loss of gaseous HO2 radicals in contact with aerosol particle surfaces on the rate and regimes of ozone production.

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