scholarly journals Nitrate formation from heterogeneous uptake of dinitrogen pentoxide during a severe winter haze in southern China

2018 ◽  
Author(s):  
Hui Yun ◽  
Weihao Wang ◽  
Tao Wang ◽  
Men Xia ◽  
Chuan Yu ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Time Resolution ◽  
Southern China ◽  
Fine Particulate Matter ◽  
Measurement Data ◽  
Heterogeneous Reactions ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Phase Reaction ◽  
Dinitrogen Pentoxide

Abstract. Nitrate (NO3−) has become a major component of fine particulate matter (PM2.5) during hazy days in China. However, the role of the heterogeneous reactions of dinitrogen pentoxide (N2O5) in nitrate formation is not well constrained. In January 2017, a severe haze event occurred in the Pearl River Delta (PRD) of southern China during which high levels of PM2.5 (~ 400 μg m−3) and O3 (~ 160 ppbv) were observed at a semi-rural site (Heshan) in the western PRD. Nitrate concentrations were up to 108 μg m−3 (1 h time resolution), and the contribution of nitrate to PM2.5 reached nearly 40 %. Concurrent increases in NO3− and ClNO2 (with a maximum value of 8.3 ppbv in 1 min time resolution) were observed in the first several hours after sunset, indicating an intense N2O5 heterogeneous uptake on aerosols. The formation potential of NO3− via N2O5 heterogeneous reactions was estimated to be 39.7 to 77.3 μg m−3 in the early hours (3 to 6 h) after sunset based on the measurement data, which could completely explain the measured increase in the NO3− concentration during the same time period. Daytime production of nitric acid from the gas-phase reaction of OH + NO2 was calculated with a chemical box model built using the Master Chemical Mechanism (MCM v3.3.1) and constrained by the measurement data. The integrated nocturnal nitrate formed via N2O5 chemistry was comparable to or even higher than the nitric acid formed during the daytime. This study confirms that N2O5 heterogeneous chemistry was a significant source of aerosol nitrate during hazy days in southern China.

scholarly journals Nitrate formation from heterogeneous uptake of dinitrogen pentoxide during a severe winter haze in southern China

2018 ◽  
Vol 18 (23) ◽  
pp. 17515-17527 ◽  
Author(s):  
Hui Yun ◽  
Weihao Wang ◽  
Tao Wang ◽  
Men Xia ◽  
Chuan Yu ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Time Resolution ◽  
Southern China ◽  
Fine Particulate Matter ◽  
Measurement Data ◽  
Heterogeneous Reactions ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Phase Reaction ◽  
Dinitrogen Pentoxide

Abstract. Nitrate (NO3-) has become a major component of fine particulate matter (PM2.5) during hazy days in China. However, the role of the heterogeneous reactions of dinitrogen pentoxide (N2O5) in nitrate formation is not well constrained. In January 2017, a severe haze event occurred in the Pearl River Delta (PRD) of southern China during which high levels of PM2.5 (∼400 µg m−3) and O3 (∼160 ppbv) were observed at a semi-rural site (Heshan) in the western PRD. Nitrate concentrations reached 108 µg m−3 (1 h time resolution), and the contribution of nitrate to PM2.5 was nearly 40 %. Concurrent increases in NO3- and ClNO2 (with a maximum value of 8.3 ppbv at a 1 min time resolution) were observed in the first several hours after sunset, indicating an intense N2O5 heterogeneous uptake by aerosols. The formation potential of NO3- via N2O5 heterogeneous reactions was estimated to be between 29.0 and 77.3 µg m−3 in the early hours (2 to 6 h) after sunset based on the measurement data, which could completely explain the measured increase in the NO3- concentration during the same time period. Daytime production of nitric acid from the gas-phase reaction of OH+NO2 was calculated with a chemical box model built using the Master Chemical Mechanism (MCM v3.3.1) and constrained by the measurement data. The integrated nocturnal nitrate formed via N2O5 chemistry was comparable to or even higher than the nitric acid formed during the day. This study confirms that N2O5 heterogeneous chemistry was a significant source of aerosol nitrate during hazy days in southern China.

scholarly journals Spatial and seasonal variability of PM<sub>2.5</sub> acidity at two Chinese megacities: insights into the formation of secondary inorganic aerosols

2012 ◽  
Vol 12 (3) ◽  
pp. 1377-1395 ◽  
Author(s):  
K. He ◽  
Q. Zhao ◽  
Y. Ma ◽  
F. Duan ◽  
F. Yang ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Temporal Variations ◽  
Early Summer ◽  
Heterogeneous Reactions ◽  
Rural Site ◽  
Urban Site ◽  
Simultaneous Increase ◽  
Northwestern Pacific ◽  
Inorganic Aerosols ◽  
Aerosol Acidity

Abstract. Aerosol acidity is one of the most important parameters influencing atmospheric chemistry and physics. Based on continuous field observations from January 2005 to May 2006 and thermodynamic modeling, we investigated the spatial and seasonal variations in PM2.5 acidity in two megacities in China, Beijing and Chongqing. Spatially, PM2.5 was generally more acidic in Chongqing than in Beijing, but a reverse spatial pattern was found within the two cities, with more acidic PM2.5 at the urban site in Beijing whereas the rural site in Chongqing. Ionic compositions of PM2.5 revealed that it was the higher concentrations of NO3− at the urban site in Beijing and the lower concentrations of Ca2+ within the rural site in Chongqing that made their PM2.5 more acidic. Temporally, PM2.5 was more acidic in summer and fall than in winter, while in the spring of 2006, the acidity of PM2.5 was higher in Beijing but lower in Chongqing than that in 2005. These were attributed to the more efficient formation of nitrate relative to sulfate as a result of the influence of Asian desert dust in 2006 in Beijing and the greater wet deposition of ammonium compared to sulfate and nitrate in 2005 in Chongqing. Furthermore, simultaneous increase of PM2.5 acidity was observed from spring to early summer of 2005 in both cities. This synoptic-scale evolution of PM2.5 acidity was accompanied by the changes in air masses origins, which were influenced by the movements of a subtropical high over the northwestern Pacific in early summer. Finally, the correlations between [NO3−]/[SO42−] and [NH4+]/[SO42−] suggests that under conditions of high aerosol acidity, heterogeneous reactions became one of the major pathways for the formation of nitrate at both cities. These findings provided new insights in our understanding of the spatial and temporal variations in aerosol acidity in Beijing and Chongqing, as well as those reported in other cities in China.

scholarly journals Exploring the atmospheric chemistry of nitrous acid (HONO) at a rural site in Southern China

2012 ◽  
Vol 12 (3) ◽  
pp. 1497-1513 ◽  
Author(s):  
X. Li ◽  
T. Brauers ◽  
R. Häseler ◽  
B. Bohn ◽  
H. Fuchs ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Southern China ◽  
Rural Site ◽  
Pearl River Delta Region ◽  
Additional Source ◽  
Mixing Ratios ◽  
Photolysis Frequency ◽  
The Pearl River

Abstract. We performed measurements of nitrous acid (HONO) during the PRIDE-PRD2006 campaign in the Pearl River Delta region 60 km north of Guangzhou, China, for 4 weeks in June 2006. HONO was measured by a LOPAP in-situ instrument which was setup in one of the campaign supersites along with a variety of instruments measuring hydroxyl radicals, trace gases, aerosols, and meteorological parameters. Maximum diurnal HONO mixing ratios of 1–5 ppb were observed during the nights. We found that the nighttime build-up of HONO can be attributed to the heterogeneous NO2 to HONO conversion on ground surfaces and the OH + NO reaction. In addition to elevated nighttime mixing ratios, measured noontime values of ≈200 ppt indicate the existence of a daytime source higher than the OH + NO→HONO reaction. Using the simultaneously recorded OH, NO, and HONO photolysis frequency, a daytime additional source strength of HONO (PM) was calculated to be 0.77 ppb h−1 on average. This value compares well to previous measurements in other environments. Our analysis of PM provides evidence that the photolysis of HNO3 adsorbed on ground surfaces contributes to the HONO formation.

scholarly journals Transport, mixing and feedback of dust, biomass burning and anthropogenic pollutants in eastern Asia: a case study

2018 ◽  
Vol 18 (22) ◽  
pp. 16345-16361 ◽  
Author(s):  
Derong Zhou ◽  
Ke Ding ◽  
Xin Huang ◽  
Lixia Liu ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Biomass Burning ◽  
Southern China ◽  
Eastern China ◽  
Measurement Data ◽  
Lower Troposphere ◽  
Climate Impacts ◽  
Eastern Asia ◽  
Pollution Episode ◽  
The Yrd

Abstract. Anthropogenic fossil fuel (FF) combustion, biomass burning (BB) and desert dust are the main sources of air pollutants around the globe but are particularly intensive and important for air quality in Asia in spring. In this study, we investigate the vertical distribution, transport characteristics, source contribution and meteorological feedback of these aerosols in a unique pollution episode that occurred in eastern Asia based on various measurement data and modeling methods. In this episode, the Yangtze River Delta (YRD) in eastern China experienced persistent air pollution, dramatically changing from secondary fine particulate pollution to dust pollution in late March 2015. The Eulerian and Lagrangian models were conducted to investigate the vertical structure, transport characteristics and mechanisms of the multi-scale, multisource and multiday air pollution episode. The regional polluted continental aerosols mainly accumulated near the surface, mixed with dust aerosol downwash from the upper planetary boundary layer (PBL) and middle–lower troposphere (MLT), and further transported by large-scale cold fronts and warm conveyor belts. BB smoke from Southeast Asia was transported by westerlies around the altitude of 3 km from southern China, was further mixed with dust and FF aerosols in eastern China and experienced long-range transport over the Pacific. These pollutants could all be transported to the YRD region and cause a structure of multilayer pollution there. These pollutants could also cause significant feedback with MLT meteorology and then enhance local anthropogenic pollution. This study highlights the importance of intensive vertical measurement in eastern China and the downwind Pacific Ocean and raises the need for quantitative understanding of environmental and climate impacts of these pollution sources.

scholarly journals Formation and sink of glyoxal and methylglyoxal in a polluted subtropical environment: observation-based photochemical analysis and impact evaluation

2020 ◽  
Vol 20 (19) ◽  
pp. 11451-11467
Author(s):  
Zhenhao Ling ◽  
Qianqian Xie ◽  
Min Shao ◽  
Zhe Wang ◽  
Tao Wang ◽  
...  
Keyword(s):  
Southern China ◽  
Oxidation Mechanism ◽  
Receptor Site ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Major Pathway ◽  
Mixing Ratios ◽  
Heterogeneous Processes ◽  
The Pearl River ◽  
Improved Model

Abstract. The dicarbonyls glyoxal (Gly) and methylglyoxal (Mgly) have been recognized as important precursors of secondary organic aerosols (SOAs) through the atmospheric heterogeneous process. In this study, field measurement was conducted at a receptor site in the Pearl River Delta (PRD) region in southern China, and an observation-based photochemical box model was subsequently applied to investigate the production and evolution of Gly and Mgly as well as their contributions to SOA formation. The model was coupled with a detailed gas-phase oxidation mechanism of volatile organic compounds (VOCs) (i.e., Master Chemical Mechanism, MCM, v3.2), heterogeneous processes of Gly and Mgly (i.e., reversible partitioning in aqueous phase, irreversible volume reactions and irreversible surface uptake processes), and the gas–particle partitioning of oxidation products. The results suggested that without considering the heterogeneous processes of Gly and Mgly on aerosol surfaces, the model would overpredict the mixing ratios of Gly and Mgly by factors of 3.3 and 3.5 compared to the observed levels. The agreement between observation and simulation improved significantly when the irreversible uptake and the reversible partitioning were incorporated into the model, which in total both contributed ∼ 62 % to the destruction of Gly and Mgly during daytime. Further analysis of the photochemical budget of Gly and Mgly showed that the oxidation of aromatics by the OH radical was the major pathway producing Gly and Mgly, followed by degradation of alkynes and alkenes. Furthermore, based on the improved model mechanism, the contributions of VOC oxidation to SOA formed from gas–particle partitioning (SOAgp) and from heterogeneous processes of Gly and Mgly (SOAhet) were also quantified. It was found that o-xylene was the most significant contributor to SOAgp formation (∼ 29 %), while m,p-xylene and toluene made dominant contributions to SOAhet formation. Overall, the heterogeneous processes of Gly and Mgly can explain ∼ 21 % of SOA mass in the PRD region. The results of this study demonstrated the important roles of heterogeneous processes of Gly and Mgly in SOA formation and highlighted the need for a better understanding of the evolution of intermediate oxidation products.

scholarly journals Chemistry and deposition in the Model of Atmospheric composition at Global and Regional scales using Inversion Techniques for Trace gas Emissions (MAGRITTEv1.0). Part A. Chemical mechanism

2018 ◽  
Author(s):  
Jean-François Müller ◽  
Trissevgeni Stavrakou ◽  
Jozef Peeters
Keyword(s):  
Heterogeneous Reactions ◽  
Oxidation Products ◽  
Chemical Degradation ◽  
Chemical Mechanism ◽  
Atmospheric Composition ◽  
Trace Gas ◽  
Gas Phase Reactions ◽  
Gas Emissions ◽  
Trace Gas Emissions ◽  
Inversion Techniques

Abstract. A new chemical mechanism for the oxidation of biogenic volatile organic compounds (BVOCs) is presented and implemented in the Model of Atmospheric composition at Global and Regional scales using Inversion Techniques for Trace gas Emissions (MAGRITTE v1.0). With a total of 99 organic species and over 240 gas-phase reactions, 67 photodissociations and 7 heterogeneous reactions, the mechanism treats the chemical degradation of isoprene – its main focus – as well as acetaldehyde, acetone, methylbutenol and the family of monoterpenes. Regarding isoprene, the mechanism incorporates a state-of-the-art representation of its oxidation scheme accounting for all major advances put forward in recent theoretical and laboratory studies. The model and its chemical mechanism are evaluated against the suite of chemical measurements from the SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) airborne campaign, demonstrating a good overall agreement for major isoprene oxidation products, although the aerosol hydrolysis of tertiary and non-tertiary nitrates remain poorly constrained. The comparisons for methylnitrate indicate a very low nitrate yield (

scholarly journals The significant contribution of HONO to secondary pollutants during a severe winter pollution event in southern China

2019 ◽  
Vol 19 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Xiao Fu ◽  
Tao Wang ◽  
Li Zhang ◽  
Qinyi Li ◽  
Zhe Wang ◽  
...  
Keyword(s):  
Southern China ◽  
Heterogeneous Reactions ◽  
Severe Winter ◽  
Peak Enhancement ◽  
Key Species ◽  
Secondary Pollutants ◽  
Light Effects ◽  
Haze Formation ◽  
The Pearl River

Abstract. Nitrous acid (HONO) can strongly affect atmospheric photochemistry in polluted regions through the production of hydroxyl radicals (OHs). In January 2017, a severe pollution episode occurred in the Pearl River Delta (PRD) of China, with maximum hourly PM2.5, ozone, and HONO levels reaching 400 µg m−3, 150 ppb, and 8 ppb, respectively, at a suburban site. The present study investigated the sources and processes generating such high HONO concentrations and the role of HONO chemistry in this severe winter episode. Four recently reported HONO sources were added to the Community Multiscale Air Quality (CMAQ) model, including RH-dependent (relative humidity) and light-enhancing effects on heterogeneous reactions, photolysis of particulate nitrate in the atmosphere, and photolysis of HNO3 and nitrate on surfaces. The revised model reproduced the observed HONO and significantly improved its performance for O3 and PM2.5. The model simulations showed that the heterogeneous generation on surfaces (with RH and light effects) was the largest contributor (72 %) to the predicted HONO concentrations, with the RH-enhancing effects more significant at nighttime and the light-enhancing effects more important in the daytime. The photolysis of total nitrate in the atmosphere and deposited on surfaces was the dominant HONO source during noon and afternoon, contributing above 50 % of the simulated HONO. The HONO photolysis was the dominant contributor to HOx production in this episode. With all HONO sources, the daytime average O3 at the Heshan site was increased by 24 ppb (or 70 %), compared to the simulation results without any HONO sources. Moreover, the simulated mean concentrations of TNO3 (HNO3+ fine particle NO3-) at the Heshan site, which was the key species for this haze formation, increased by about 17 µg m−3 (67 %) due to the HONO chemistry, and the peak enhancement reached 55 µg m−3. This study highlights the key role of HONO chemistry in the formation of winter haze in a subtropical environment.

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