scholarly journals Modeling the impact of heterogeneous reactions of chlorine on summertime nitrate formation in Beijing, China

2019 ◽  
Vol 19 (10) ◽  
pp. 6737-6747 ◽  
Author(s):  
Xionghui Qiu ◽  
Qi Ying ◽  
Shuxiao Wang ◽  
Lei Duan ◽  
Jian Zhao ◽  
...  
Keyword(s):  
Heterogeneous Reaction ◽  
Particle Surface ◽  
Heterogeneous Reactions ◽  
Sensitivity Analyses ◽  
Uptake Coefficient ◽  
Transport Models ◽  
Nitrate Concentrations ◽  
The Impact ◽  
Beijing China ◽  
Significant Underestimation

Abstract. Comprehensive chlorine heterogeneous chemistry is incorporated into the Community Multiscale Air Quality (CMAQ) model to evaluate the impact of chlorine-related heterogeneous reaction on diurnal and nocturnal nitrate formation and quantify the nitrate formation from gas-to-particle partitioning of HNO3 and from different heterogeneous pathways. The results show that these heterogeneous reactions increase the atmospheric Cl2 and ClNO2 level (∼ 100 %), which further affects the nitrate formation. Sensitivity analyses of uptake coefficients show that the empirical uptake coefficient for the O3 heterogeneous reaction with chlorinated particles may lead to the large uncertainties in the predicted Cl2 and nitrate concentrations. The N2O5 uptake coefficient with particulate Cl− concentration dependence performs better in capturing the concentration of ClNO2 and nocturnal nitrate concentration. The reaction of OH and NO2 in the daytime increases the nitrate by ∼15 % when the heterogeneous chlorine chemistry is incorporated, resulting in more nitrate formation from HNO3 gas-to-particle partitioning. By contrast, the contribution of the heterogeneous reaction of N2O5 to nitrate concentrations decreases by about 27 % in the nighttime, when its reactions with chlorinated particles are considered. However, the generated gas-phase ClNO2 from the heterogeneous reaction of N2O5 and chlorine-containing particles further reacts with the particle surface to increase the nitrate by 6 %. In general, this study highlights the potential of significant underestimation of daytime concentrations and overestimation of nighttime nitrate concentrations for chemical transport models without proper chlorine chemistry in the gas and particle phases.

scholarly journals Modeling the impact of heterogeneous reactions of chlorine on summertime nitrate formation in Beijing, China

2018 ◽  
Author(s):  
Xionghui Qiu ◽  
Qi Ying ◽  
Shuxiao Wang ◽  
Lei Duan ◽  
Jian Zhao ◽  
...  
Keyword(s):  
Nitrate Concentration ◽  
Heterogeneous Reaction ◽  
Heterogeneous Reactions ◽  
Sensitivity Analyses ◽  
Uptake Coefficient ◽  
Transport Models ◽  
Nitrate Concentrations ◽  
The Impact ◽  
Beijing China ◽  
Significant Underestimation

Abstract. A comprehensive chlorine heterogeneous chemistry is incorporated into the Community Multiscale Air Quality (CMAQ) model to evaluate the impact of chlorine-related heterogeneous reaction on diurnal and nocturnal nitrate formation and quantify the nitrate formation from gas-to-particle partitioning of HNO3 and from different heterogeneous pathways. The results show that these heterogeneous reactions increase the atmospheric Cl2 and ClNO2 level, leading to an increase of the nitrate concentration by ~ 10 % in the daytime. However, these reactions also lead to a decrease the nocturnal nitrate by ~ 20 %. Sensitivity analyses of uptake coefficients show that the empirical uptake coefficient for the O3 heterogeneous reaction with chlorinated particles may lead to the large uncertainties in the predicted Cl2 and nitrate concentrations. The N2O5 uptake coefficient with particulate Cl− concentration dependence performs better to capture the concentration of ClNO2 and nocturnal nitrate concentration. The reaction rate of OH and NO2 in daytime increases by ~ 15 % when the heterogeneous chlorine chemistry is incorporated, resulting more nitrate formation from HNO3 gas-to-particle partitioning. By contrast, the contribution of the heterogeneous reaction of N2O5 to nitrate concentrations decreases by about 27 % in the nighttime when its reactions with chloriated particles are considered. However, the generated gas-phase ClNO2 from the heterogeneous reaction of N2O5 and chlorine-containing particles further decompose to increase the nitrate by 6 %. In general, this study highlights the potential of significant underestimation of daytime and overestimation of nighttime nitrate concentrations for chemical transport models without proper chlorine chemistry in the gas and particle phases.

scholarly journals Ozone impacts of gas–aerosol uptake in global chemistry transport models

2018 ◽  
Vol 18 (5) ◽  
pp. 3147-3171 ◽  
Author(s):  
Scarlet Stadtler ◽  
David Simpson ◽  
Sabine Schröder ◽  
Domenico Taraborrelli ◽  
Andreas Bott ◽  
...  
Keyword(s):  
East Asia ◽  
Surface Area ◽  
General Circulation ◽  
Heterogeneous Reaction ◽  
Circulation Model ◽  
Photochemical Reactions ◽  
Heterogeneous Reactions ◽  
Transport Models ◽  
Global Pattern ◽  
The Impact

Abstract. The impact of six heterogeneous gas–aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, the Meteorological Synthesizing Centre-West of the European Monitoring and Evaluation Programme (EMEP MSC-W) and the European Centre Hamburg general circulation model combined with versions of the Hamburg Aerosol Model and Model for Ozone and Related chemical Tracers (ECHAM-HAMMOZ). Species undergoing heterogeneous reactions in both models include N2O5, NO3, NO2, O3, HNO3, and HO2. Since heterogeneous reactions take place at the aerosol surface area, the modelled surface area density (Sa) of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in east Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N2O5. Nevertheless, NO2, HNO3, and HO2 heterogeneous reactions gain relevance particularly in east Asia due to the presence of high NOx concentrations and high Sa in the same region. The heterogeneous reaction of O3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N2O5 reactions show strong seasonal variations, with the biggest impacts on O3 in springtime when photochemical reactions are active and N2O5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are incorporated. Our results are loosely consistent with results from earlier studies, although the magnitude of changes induced by N2O5 reaction is at the low end of estimates, which seems to fit a trend, whereby the more recent the study the lower the impacts of these reactions.

scholarly journals Ozone Impacts of Gas-Aerosol Uptake in Global Chemistry Transport Models

2017 ◽  
Author(s):  
Scarlet Stadtler ◽  
David Simpson ◽  
Sabine Schröder ◽  
Domenico Taraborrelli ◽  
Andreas Bott ◽  
...  
Keyword(s):  
East Asia ◽  
Surface Area ◽  
Heterogeneous Reaction ◽  
Photochemical Reactions ◽  
Heterogeneous Reactions ◽  
Transport Models ◽  
Global Pattern ◽  
Temporal Correlations ◽  
The One ◽  
The Impact

Abstract. The impact of six heterogeneous gas-aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, EMEP MSC-W and ECHAM-HAMMOZ. Species undergoing heterogeneous reactions in both models include N2O5, NO3, NO2, O3, HNO3 and HO2. Since heterogeneous reactions take place at the aerosol surface area, the modeled surface area density Sa of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in East Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N2O5. Nevertheless, NO2, HNO3 and HO2 heterogeneous reaction gain relevance particularly in East Asia due to the presence of high NOx concentrations and high Sa in the same region, although ECHAM-HAMMOZ showed much stronger responses than EMEP in this respect. The heterogeneous reaction of O3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N2O5 reactions show strong seasonal variations, with biggest impacts on O3 in spring time when photochemical reactions are active and N2O5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are incorporated.

scholarly journals Heterogeneous reaction of HO<sub>2</sub> with airborne TiO<sub>2</sub> particles and its implication for climate change mitigation strategies

2017 ◽  
Author(s):  
Daniel R. Moon ◽  
Giorgio S. Taverna ◽  
Clara Anduix-Canto ◽  
Trevor Ingham ◽  
Martyn P. Chipperfield ◽  
...  
Keyword(s):  
Transport Model ◽  
Heterogeneous Reaction ◽  
Three Dimensional ◽  
Mitigation Strategies ◽  
Heterogeneous Reactions ◽  
Chemical Transport Model ◽  
Flow Tube ◽  
Tio2 Particles ◽  
The Impact ◽  
Change Mitigation

Abstract. One geoengineering mitigation strategy for global temperature rises resulting from the increased concentrations of greenhouse gases is to inject particles into the stratosphere to scatter solar radiation back to space, with TiO2 particles emerging as a possible candidate. Uptake coefficients of HO2, γ(HO2), onto sub-micrometre TiO2 particles were measured at room temperature and different relative humidities (RH) using an atmospheric pressure aerosol flow tube coupled to a sensitive HO2 detector. Values of γ(HO2) increased from 0.021 ± 0.001 to 0.036 ± 0.007 as the RH was increased from 11 % to 66 %, and the increase in γ(HO2) correlated with the number of monolayers of water surrounding the TiO2 particles. The impact of the uptake of HO2 onto TiO2 particles on stratospheric concentrations of HO2 and O3 was simulated using the TOMCAT three-dimensional chemical transport model. The model showed that by injecting the amount of TiO2 required to achieve the same cooling effect as the Mt. Pinatubo eruption, heterogeneous reactions between HO2 and TiO2 would have a negligible effect on stratospheric concentrations of HO2 and O3.

Heterogeneous formation of HONO and its impacts on haze formation in the YRD region of China

2020 ◽  
Author(s):  
Jun Zheng ◽  
Xiaowen Shi ◽  
Yan Ma
Keyword(s):  
Heterogeneous Reaction ◽  
Particle Surface ◽  
Ground Surface ◽  
Yangtze River Delta ◽  
Heterogeneous Reactions ◽  
Atmospheric Oxidation ◽  
Industrial Zone ◽  
Particle Surface Area ◽  
Oxidation Capacity ◽  
The Yrd

&lt;p&gt;A suite of instruments were deployed to simultaneously measure nitrous acid (HONO), nitrogen oxides (NO&lt;sub&gt;x&lt;/sub&gt;= NO + NO&lt;sub&gt;2&lt;/sub&gt;), carbon monoxide (CO), ozone (O&lt;sub&gt;3&lt;/sub&gt;), volatile organic compounds (VOCs, including formaldehyde (HCHO)) and meteorological parameters near a typical industrial zone in Nanjing of the Yangtze River Delta region, China. High levels of HONO were detected using a wet chemistry-based method. HONO ranged from 0.03-7.04 ppbv with an average of 1.32 &amp;#177;0.92 ppbv. Elevated daytime HONO was frequently observed with a minimum of several hundreds of pptv on average, which cannot be explained by the homogeneous OH + NO reaction (P&lt;sub&gt;OH+NO&lt;/sub&gt;) alone, especially during periods with high loadings of particulate matters (PM&lt;sub&gt;2.5&lt;/sub&gt;). The HONO chemistry and its impact on atmospheric oxidation capacity in the study area were further investigated using a MCM-box model. The results show that the average hydroxyl radical (OH) production rate was dominated by the photolysis of HONO (7.13&amp;#215;10&lt;sup&gt;6&lt;/sup&gt;molecules cm&lt;sup&gt;-3 &lt;/sup&gt;s&lt;sup&gt;-1&lt;/sup&gt;), followed by ozonolysis of alkenes (3.94&amp;#215;10&lt;sup&gt;6&lt;/sup&gt;molecules cm&lt;sup&gt;-3 &lt;/sup&gt;s&lt;sup&gt;-1&lt;/sup&gt;), photolysis of O&lt;sub&gt;3&lt;/sub&gt;(2.46&amp;#215;10&lt;sup&gt;6&lt;/sup&gt;molecules cm&lt;sup&gt;-3 &lt;/sup&gt;s&lt;sup&gt;-1&lt;/sup&gt;) and photolysis of HCHO (1.60&amp;#215;10&lt;sup&gt;6&lt;/sup&gt;molecules cm&lt;sup&gt;-3 &lt;/sup&gt;s&lt;sup&gt;-1&lt;/sup&gt;), especially within the plumes originated from the industrial zone. The observed similarity between HONO/NO&lt;sub&gt;2&lt;/sub&gt;and HONO in diurnal profiles strongly suggests that HONO in the study area was likely originated from NO&lt;sub&gt;2&lt;/sub&gt;heterogeneous reactions. The averagenighttimeNO&lt;sub&gt;2&lt;/sub&gt;to HONO conversion ratewas determined to be ~0.9% hr&lt;sup&gt;-1&lt;/sup&gt;. Good correlation between nocturnal HONO/NO&lt;sub&gt;2&lt;/sub&gt;and the products of particle surface area density (S/V) and relative humidity (RH), S/V&amp;#215;RH,supports the heterogeneous NO&lt;sub&gt;2&lt;/sub&gt;/H&lt;sub&gt;2&lt;/sub&gt;O reaction mechanism. The other HONO source, designated as P&lt;sub&gt;unknonwn&lt;/sub&gt;, was about twice as much as P&lt;sub&gt;OH+NO &lt;/sub&gt;on average and displayed a diurnal profile with an evidently photo-enhanced feature, i.e., photosensitized reactions of NO&lt;sub&gt;2&lt;/sub&gt;may be an important daytime HONO source. Nevertheless, our results suggest that daytime HONO formation was mostly due to the light-induced conversion of NO&lt;sub&gt;2&lt;/sub&gt;on aerosol surfaces but heterogeneous NO&lt;sub&gt;2&lt;/sub&gt;reactions on ground surface dominated nocturnal HONO production. Concurred elevated HONO and PM&lt;sub&gt;2.5&lt;/sub&gt;levels strongly indicate that high HONO may increase the atmospheric oxidation capacity and further promote the formation of secondary aerosols, which may in turn synergistically boost NO&lt;sub&gt;2&lt;/sub&gt;/HONO conversion by providing more heterogeneous reaction sites.&lt;/p&gt;

scholarly journals Comparative study of the effect of water on the heterogeneous reactions of carbonyl sulfide on the surface of α-Al<sub>2</sub>O<sub>3</sub> and MgO

2009 ◽  
Vol 9 (3) ◽  
pp. 12483-12517
Author(s):  
Y. Liu ◽  
Q. Ma ◽  
H. He
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Heterogeneous Reaction ◽  
Water Vapor Pressure ◽  
Carbonyl Sulfide ◽  
Heterogeneous Reactions ◽  
Uptake Coefficient ◽  
Effect Of Water ◽  
Mineral Dusts ◽  
Α Al2o3

Abstract. The heterogeneous reaction on mineral dust was considered as a new sink of OCS in the troposphere. Here we compared the heterogeneous reactions of carbonyl sulfide (OCS) on the surface of α-Al2O3 and MgO and the effect of water on the reactions at 300 K using Knudsen cell – mass spectrometry, diffuse reflectance infrared Fourier transform spectroscopy, and temperature programmed reactions. H2S and CO2 were found to be hydrolysis products of OCS on both α-Al2O3 and MgO at ambient temperature. At low water vapor pressure, when water vapor pressure in the Knudsen cell reactor increased from 2.3×10−6 to 6.8×10−6 Torr, the initial true uptake coefficient of OCS on α-Al2O3 decreased from 4.70×10−7 to 3.59×10−7; while it increased from 5.19×10−7 to 6.48×10−7 on MgO under the same conditions. At high relative humidity, the observed uptake coefficients of OCS on α-Al2O3 and MgO decreased from 4.63×10−6 to 1.00×10−6 and from 9.72×10−5 to 7.68×10−5, respectively, when RH increased from 0.07 to 0.67 which corresponding to 1.7–15.9 Torr of water vapor pressure. In the RH region of 0.17–0.67, the average observed uptake coefficient of OCS on α-Al2O3 and MgO was equal to 8.34±2.19×10−7 and 8.19±0.48×10−5, respectively. The restrictive effect of water on the heterogeneous reaction of OCS on the surface of α-Al2O3 and MgO was found to be related to competitive adsorption between water and OCS molecules; while the promotive effect of water on the heterogeneous reaction of OCS on the surface of MgO at low coverage was ascribed to the formation of surface hydroxyl groups. When the environmental RH was greater than the RH of the monolayer, which occurred readily at the typical relative humidity of the troposphere, liquid membrane formed on the mineral dusts, especially, the basic liquid membrane formed on the basic component of mineral dusts may be the primary contributor to the heterogeneous hydrolysis of OCS in the troposphere.

scholarly journals Acyl peroxy nitrate measurements during the photochemical smog season in Beijing, China

2011 ◽  
Vol 11 (3) ◽  
pp. 10265-10303 ◽  
Author(s):  
Z. Xu ◽  
J. Zhang ◽  
G. Yang ◽  
M. Hu
Keyword(s):  
Particle Surface ◽  
Heterogeneous Reactions ◽  
Anthropogenic Sources ◽  
World Health ◽  
Photochemical Smog ◽  
Particle Surface Area ◽  
Mixing Ratios ◽  
Total Particle ◽  
Health Organization ◽  
Beijing China

Abstract. In situ measurements of acyl peroxy nitrates (PANs), including peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), and peroxymethacryloyl nitrate (MPAN), were conducted using a gas chromatography-electron capture detector (GC-ECD) system during the photochemical smog season in Beijing, China. The maximum mixing ratios were 17.81, 2.48, and 0.27 ppbv for PAN, PPN, and MPAN, respectively. During the measurement period, PAN levels twice exceeded the maximum recommended mixing ratio established by the World Health Organization (WHO). Average ratios of PAN/PPN, PAN/MPAN, and PPN/MPAN were 7.41, 47.65, and 6.91, respectively. The average ratio of PAN/O3 (0.15) in Beijing was significantly higher than those in other areas studied. The frequencies of PANs showed both Gaussian and Weibull modes of distribution. Wind direction was closely related to PAN variation. Anthropogenic sources played an important role in PAN formation, as estimated from PPN and MPAN levels. Relative humidity (RH) and total particle surface area were related with the heterogeneous reactions of PANs with surface concentrations of particulate matter ≤10 μm in diameter.

scholarly journals Sensitivity of nitrate aerosols to ammonia emissions and to nitrate chemistry: implications for present and future nitrate optical depth

2016 ◽  
Vol 16 (3) ◽  
pp. 1459-1477 ◽  
Author(s):  
F. Paulot ◽  
P. Ginoux ◽  
W. F. Cooke ◽  
L. J. Donner ◽  
S. Fan ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Heterogeneous Reaction ◽  
Convective Transport ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Ammonia Emissions ◽  
Near Surface ◽  
Nitrate Concentrations ◽  
The Impact

Abstract. We update and evaluate the treatment of nitrate aerosols in the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric model (AM3). Accounting for the radiative effects of nitrate aerosols generally improves the simulated aerosol optical depth, although nitrate concentrations at the surface are biased high. This bias can be reduced by increasing the deposition of nitrate to account for the near-surface volatilization of ammonium nitrate or by neglecting the heterogeneous production of nitric acid to account for the inhibition of N2O5 reactive uptake at high nitrate concentrations. Globally, uncertainties in these processes can impact the simulated nitrate optical depth by up to 25 %, much more than the impact of uncertainties in the seasonality of ammonia emissions (6 %) or in the uptake of nitric acid on dust (13 %). Our best estimate for fine nitrate optical depth at 550 nm in 2010 is 0.006 (0.005–0.008). In wintertime, nitrate aerosols are simulated to account for over 30 % of the aerosol optical depth over western Europe and North America. Simulated nitrate optical depth increases by less than 30 % (0.0061–0.010) in response to projected changes in anthropogenic emissions from 2010 to 2050 (e.g., −40 % for SO2 and +38 % for ammonia). This increase is primarily driven by greater concentrations of nitrate in the free troposphere, while surface nitrate concentrations decrease in the midlatitudes following lower concentrations of nitric acid. With the projected increase of ammonia emissions, we show that better constraints on the vertical distribution of ammonia (e.g., convective transport and biomass burning injection) and on the sources and sinks of nitric acid (e.g., heterogeneous reaction on dust) are needed to improve estimates of future nitrate optical depth.

Effect of potential HONO sources on ROx budgets and SOA and PAN formation in North China in winter

2020 ◽  
Author(s):  
Jingwei Zhang ◽  
Junling An
Keyword(s):  
Nitrous Acid ◽  
North China ◽  
Heterogeneous Reaction ◽  
Chemical Transport ◽  
Heterogeneous Reactions ◽  
Transport Models ◽  
Chemical Transport Models ◽  
High Concentrations ◽  
Haze Days ◽  
Bth Region

&lt;p&gt;Recent wintertime observations in north China found high concentrations of nitrous acid (HONO), secondary organic aerosols (SOA) and peroxyacetyl nitrate (PAN), especially during heavy haze periods, indicating stronger atmospheric oxidation capacity in winter haze days. Researchers speculated that HONO formation was enhanced in haze days through NO&lt;sub&gt;2&lt;/sub&gt; heterogeneous reaction on aerosol surfaces, and high concentrations of HONO during daytime further improved SOA and PAN formation.&lt;/p&gt;&lt;p&gt;In this study, the WRF-Chem model updated with six potential HONO sources was used to quantify the impacts of potential HONO sources on the production and loss rates of RO&lt;sub&gt;x&lt;/sub&gt; ( OH+HO&lt;sub&gt;2&lt;/sub&gt;+RO&lt;sub&gt;2&lt;/sub&gt;) radicals, and on the concentrations of SOA and PAN in the Beijing-Tianjin-Hebei (BTH) region of China during wintertime of 2017. HONO simulations were greatly improved after considering the six potential sources, NO&lt;sub&gt;2&lt;/sub&gt; heterogeneous reactions were the main sources of HONO. HONO photolysis was the key precursors of primary OH while the contribution of O&lt;sub&gt;3&lt;/sub&gt; photolysis to OH could be neglected, the potential HONO sources remarkably accelerated RO&lt;sub&gt;x&lt;/sub&gt; cycles, significantly improved SOA and PAN simulations, especially in heavy polluted periods. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting relevant studies.&lt;/p&gt;

scholarly journals A comprehensive characterisation of Asian dust storm particles: chemical composition, reactivity to SO<sub>2</sub>, and hygroscopic property

2010 ◽  
Vol 10 (4) ◽  
pp. 8899-8925 ◽  
Author(s):  
Q. Ma ◽  
Y. Liu ◽  
C. Liu ◽  
J. Ma ◽  
H. He
Keyword(s):  
Dust Storm ◽  
Heterogeneous Reaction ◽  
Cell Mass ◽  
Asian Dust ◽  
Dust Storms ◽  
Source Distribution ◽  
Dust Particles ◽  
Uptake Coefficient ◽  
Asian Dust Storm ◽  
The Impact

Abstract. Mineral dust comprises of a significant fraction of the globe's aerosol loading. Yet it remains the largest uncertainty in future climate predictions due to the complexity in its components and physico-chemical properties. Multi-analysis methods, including SEM-EDX, FTIR, BET, TPD/mass, and Knudsen cell/mass, were used in the present study to characterise Asian dust storm particles. The morphology, element fraction, source distribution, true uptake coefficient of SO2 and hygroscopic behaviour were studied. The major components of Asian dust storm particles were found to consist of aluminosilicate, SiO2, and CaCO3, which were coated with organic compounds and inorganic nitrate. The dust storm particles have a low reactivity to SO2 (true uptake coefficient of 5.767×10−6) which limits the conversion of SO2 to sulfate during a dust storm period. The low reactivity also demonstrated that the heterogeneous reaction of SO2, in both dry and humid air conditions, had little effect on the hygroscopic behaviour of the dust particles. These results indicate that the impact of dust storms on atmospheric SO2 removal should not be overestimated.

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