scholarly journals Secondary aerosol formation alters CCN activity in the North China Plain

2021 ◽  
Vol 21 (9) ◽  
pp. 7409-7427
Author(s):  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Nan Ma ◽  
Juan Hong ◽  
Yele Sun ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Size Range ◽  
Particle Mass ◽  
Rural Site ◽  
Formation Mechanisms ◽  
The North ◽  
The North China Plain ◽  
The Impact ◽  
Ccn Activity

Abstract. Secondary aerosols (SAs, including secondary organic and inorganic aerosols, SOAs and SIAs) are predominant components of aerosol particles in the North China Plain (NCP), and their formation has significant impacts on the evolution of particle size distribution (PNSD) and hygroscopicity. Previous studies have shown that distinct SA formation mechanisms can dominate under different relative humidity (RH). This would lead to different influences of SA formation on the aerosol hygroscopicity and PNSD under different RH conditions. Based on the measurements of size-resolved particle activation ratio (SPAR), hygroscopicity distribution (GF-PDF), PM2.5 chemical composition, PNSD, meteorology and gaseous pollutants in a recent field campaign, McFAN (Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain), conducted during the autumn–winter transition period in 2018 at a polluted rural site in the NCP, the influences of SA formation on cloud condensation nuclei (CCN) activity and CCN number concentration (NCCN) calculation under different RH conditions were studied. Results suggest that during daytime, SA formation could lead to a significant increase in NCCN and a strong diurnal variation in SPAR at supersaturations lower than 0.07 %. During periods with daytime minimum RH exceeding 50 % (high RH conditions), SA formation significantly contributed to the particle mass and size changes in a broad size range of 150 to 1000 nm, leading to NCCN (0.05 %) increases within the size range of 200 to 500 nm and mass concentration growth mainly for particles larger than 300 nm. During periods with daytime minimum RH below 30 % (low RH conditions), SA formation mainly contributed to the particle mass and size and NCCN changes for particles smaller than 300 nm. As a result, under the same amount of mass increase induced by SA formation, the increase of NCCN (0.05 %) was stronger under low RH conditions and weaker under high RH conditions. Moreover, the diurnal variations of the SPAR parameter (inferred from CCN measurements) due to SA formation varied with RH conditions, which was one of the largest uncertainties within NCCN predictions. After considering the SPAR parameter (estimated through the number fraction of hygroscopic particles or mass fraction of SA), the relative deviation of NCCN (0.05 %) predictions was reduced to within 30 %. This study highlights the impact of SA formation on CCN activity and NCCN calculation and provides guidance for future improvements of CCN predictions in chemical-transport models and climate models.

Secondary aerosol formation alters CCN activity in the North China Plain

2021 ◽  
Author(s):  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Nan Ma ◽  
Juan Hong ◽  
Yele Sun ◽  
...  
Keyword(s):  
Particle Size ◽  
North China Plain ◽  
North China ◽  
Particle Mass ◽  
Mixing State ◽  
Particle Size Range ◽  
The North ◽  
The North China Plain ◽  
Aerosol Mixing State ◽  
Ccn Activity

<p>The formation of secondary aerosols (SA, including secondary organic and inorganic aerosols, SOA and SIA) were the dominant sources of aerosol particles in the North China Plain and can result in significant variations of particle size distribution (PNSD) and hygroscopicity. Earlier studies have shown that the mechanism of SA formation can be affected by relative humidity (RH), and thus has different influences on the aerosol hygroscopicity and PNSD under different RH conditions. Based on the measurements of size-resolved particle activation ratio (SPAR), hygroscopicity distribution (GF-PDF), PM<sub>2.5</sub> chemical composition, PNSD, meteorology and gaseous pollutants in a recent field campaign McFAN (Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain) conducted at Gucheng site from November 16<sup>th</sup> to December 16<sup>th</sup> in 2018, the influences of SA formation on CCN activity and CCN number concentration (N<sub>CCN</sub>) calculation at super-saturation of 0.05% under different RH conditions were studied. Measurements showed that during daytime, SA formation could lead to a significant increase in N<sub>CCN</sub> and a strong diurnal variation in CCN activity. During periods with daytime minimum RH exceeding 50% (high RH conditions), SA formation significantly contributed to the particle mass/size changes in wide particle size range of 150 nm to 1000 nm, and led to an increase of N<sub>CCN</sub> in particle size range of 200 nm to 300 nm, while increases in particle mass concentration mainly occurred within particle sizes larger than 300nm. During periods with daytime minimum RH below 30% in (low RH conditions), SA formation mainly contributed to the particle mass/size and N<sub>CCN</sub> changes in particle sizes smaller than 300 nm. As a result, under the same amount SA formation induced mass increase, the increase of N<sub>CCN</sub> was weaker under high RH conditions, while stronger under low RH conditions. Moreover, the diurnal variations of aerosol mixing state (inferred from CCN measurements) due to SA formation was different under different RH conditions. If the variations of the aerosol mixing state were not considered, estimations of N<sub>CCN</sub> would bear significant deviations. By applying aerosol mixing state estimated by number fraction of hygroscopic particles from measurements of particle hygroscopicity or mass fraction of SA from measurements of particle chemical compositions, N<sub>CCN</sub> calculation can be largely improved with relative deviation within 30%. This study improves the understanding of the impact of SA formation on CCN activity and N<sub>CCN</sub> calculation, which is of great significance for improving parameterization of SA formation in aerosol models and CCN calculation in climate models.</p>

scholarly journals Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

2016 ◽  
Vol 16 (17) ◽  
pp. 10985-11000 ◽  
Author(s):  
Yin Wang ◽  
Zhongming Chen ◽  
Qinqin Wu ◽  
Hao Liang ◽  
Liubin Huang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Direct Production ◽  
The North ◽  
The North China Plain ◽  
The Impact ◽  
Haze Days

Abstract. Measurements of atmospheric peroxides were made during Wangdu Campaign 2014 at Wangdu, a rural site in the North China Plain (NCP) in summer 2014. The predominant peroxides were detected to be hydrogen peroxide (H2O2), methyl hydroperoxide (MHP) and peroxyacetic acid (PAA). The observed H2O2 reached up to 11.3 ppbv, which was the highest value compared with previous observations in China at summer time. A box model simulation based on the Master Chemical Mechanism and constrained by the simultaneous observations of physical parameters and chemical species was performed to explore the chemical budget of atmospheric peroxides. Photochemical oxidation of alkenes was found to be the major secondary formation pathway of atmospheric peroxides, while contributions from alkanes and aromatics were of minor importance. The comparison of modeled and measured peroxide concentrations revealed an underestimation during biomass burning events and an overestimation on haze days, which were ascribed to the direct production of peroxides from biomass burning and the heterogeneous uptake of peroxides by aerosols, respectively. The strengths of the primary emissions from biomass burning were on the same order of the known secondary production rates of atmospheric peroxides during the biomass burning events. The heterogeneous process on aerosol particles was suggested to be the predominant sink for atmospheric peroxides. The atmospheric lifetime of peroxides on haze days in summer in the NCP was about 2–3 h, which is in good agreement with the laboratory studies. Further comprehensive investigations are necessary to better understand the impact of biomass burning and heterogeneous uptake on the concentration of peroxides in the atmosphere.

scholarly journals Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

2016 ◽  
Author(s):  
Yin Wang ◽  
Zhongming Chen ◽  
Qinqin Wu ◽  
Hao Liang ◽  
Liubin Huang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Direct Production ◽  
The North ◽  
The North China Plain ◽  
The Impact ◽  
Haze Days

Abstract. Measurements of atmospheric peroxides were made during Wangdu Campaign 2014 at Wangdu, a rural site in the North China Plain (NCP) in summer 2014. The predominant peroxides were detected to be hydrogen peroxide (H2O2), methyl hydroperoxide (MHP) and peroxyacetic acid (PAA). The observed H2O2 reached up to 11.3 ppbv, which was the highest value compared with previous observations in China at summer time. A box model simulation based on the Master Chemical Mechanism and constrained by the simultaneous observations of physical parameters and chemical species was performed to explore the chemical budget of atmospheric peroxides. Photochemical oxidation of alkenes was found to be the major secondary formation pathway of atmospheric peroxides, while contributions from alkanes and aromatics were of minor importance. The comparison of modelled and measured peroxide concentrations revealed an underestimation during biomass burning events and an overestimation on haze days, which were ascribed to the direct production of peroxides from biomass burning and the heterogeneous uptake of peroxides by aerosols, respectively. The strengths of the primary emissions from biomass burning were on the same order of the known secondary production rates of atmospheric peroxides during the biomass burning events. The heterogeneous process on aerosol particles was suggested to be the predominant sink for atmospheric peroxides. The atmospheric lifetime of peroxides on haze days in summer in the NCP was about 2–3 hours, which is in good agreement with the laboratory studies. Further comprehensive investigations are necessary to better understand the impact of biomass burning and heterogeneous uptake on the concentration of peroxides in the atmosphere.

scholarly journals Summertime fine particulate nitrate pollution in the North China Plain: increasing trends, formation mechanisms and implications for control policy

2018 ◽  
Vol 18 (15) ◽  
pp. 11261-11275 ◽  
Author(s):  
Liang Wen ◽  
Likun Xue ◽  
Xinfeng Wang ◽  
Caihong Xu ◽  
Tianshu Chen ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Nitrate Pollution ◽  
Rural Site ◽  
Effective Control ◽  
Urban Site ◽  
Formation Mechanisms ◽  
The North ◽  
The North China Plain ◽  
Nitrate Aerosol

Abstract. Nitrate aerosol makes up a significant fraction of fine particles and plays a key role in regional air quality and climate. The North China Plain (NCP) is one of the most industrialized and polluted regions in China. To obtain a holistic understanding of the nitrate pollution and its formation mechanisms over the NCP region, intensive field observations were conducted at three sites during summertime in 2014–2015. The measurement sites include an urban site in downtown Jinan – the capital city of Shandong Province –, a rural site downwind of Jinan city, and a remote mountain site at Mt. Tai (1534 m a.s.l.). Elevated nitrate concentrations were observed at all three sites despite distinct temporal and spatial variations. Using historical observations, the nitrate ∕ PM2.5 and nitrate ∕ sulfate ratios have statistically significantly increased in Jinan (2005–2015) and at Mt. Tai (from 2007 to 2014), indicating the worsening situation of regional nitrate pollution. A multiphase chemical box model (RACM–CAPRAM) was deployed and constrained by observations to elucidate the nitrate formation mechanisms. The principal formation route is the partitioning of gaseous HNO3 to the aerosol phase during the day, whilst the nocturnal nitrate formation is dominated by the heterogeneous hydrolysis of N2O5. The daytime nitrate production in the NCP region is mainly limited by the availability of NO2 and to a lesser extent by O3 and NH3. In comparison, the nighttime formation is controlled by both NO2 and O3. The presence of NH3 contributes to the formation of nitrate aerosol during the day, while there is slightly decreasing nitrate formation at night. Our analyses suggest that controlling NOx and O3 is an efficient way, at the moment, to mitigate nitrate pollution in the NCP region, where NH3 is usually in excess in summer. This study provides observational evidence of a rising trend of nitrate aerosol as well as scientific support for formulating effective control strategies for regional haze in China.

scholarly journals Role of ambient ammonia in particulate ammonium formation at a rural site in the North China Plain

2017 ◽  
Author(s):  
Zhaoyang Meng ◽  
Xiaobin Xu ◽  
Weili Lin ◽  
Yulin Xie ◽  
Bo Song ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Meteorological Conditions ◽  
Water Soluble ◽  
Precipitation Event ◽  
Rural Site ◽  
Formation Mechanisms ◽  
The North ◽  
The North China Plain ◽  
Particulate Ammonium

Abstract. The real-time measurements of NH3 and trace gases were conducted, in conjunction with semi-continuous measurements of water-soluble ions in PM2.5 at a rural site in the North China Plain (NCP) from May to September 2013 in order to better understand of chemical characteristics for ammonia, and of the impact on formation of secondary ammonium aerosols in the NCP. Extremely high NH3 and NH4+ concentrations were observed after a precipitation event within 7–10 days following urea application. Elevated NH3 levels coincided with elevated NH4+, suggesting that NH3 plays a vital role in enhancing particulate ammonium. For the sampling period, the average oxidation/conversion ratios for SO42− (SOR), NO3− (NOR) and NH4+ (NHR) were estimated to be 64 %, 24 % and 30 %, respectively. The increased NH3 concentrations mainly from agricultural activities, coincided with the prevailing meteorological conditions could promote the secondary transformation, resulting in higher hourly SOR, NOR and NHR. The concentrations of NH3, NH4+, and NHR had clear diurnal variations, which could be attributed to their sources, meteorological conditions, and formation mechanisms. The back trajectory analysis indicates that the transport of air masses from the North China Plain region contributed to the atmospheric NH3 variations, and both regional sources and long-distance transport from southeast played important roles in the observed ammonium aerosol at rural site in the NCP. The findings of this study are expected to facilitate developing future NH3 emission control policies for the North China Plain.

scholarly journals Secondary aerosol formation alters CCN activity in the North China Plain

2020 ◽  
Author(s):  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Nan Ma ◽  
Juan Hong ◽  
Yele Sun ◽  
...  
Keyword(s):  
Particle Size ◽  
North China Plain ◽  
North China ◽  
Particle Mass ◽  
Particle Size Range ◽  
The North ◽  
The North China Plain ◽  
Mass Size ◽  
Aerosol Mixing State ◽  
Ccn Activity

Abstract. The formation of secondary aerosols (SA, including secondary organic and inorganic aerosols, SOA and SIA) is the dominant source of aerosol particles in the North China Plain and has a significant impact on the variations of particle size distribution (PNSD) and hygroscopicity. Previous studies have shown that the mechanism of SA formation can be affected by relative humidity (RH), and thus has different influences on the aerosol hygroscopicity and PNSD under different RH conditions. Based on the measurements of size-resolved particle activation ratio (SPAR), hygroscopicity distribution (GF-PDF), PM2.5 chemical composition, PNSD, meteorology and gaseous pollutants in a recent field campaign McFAN (Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain) conducted at Gucheng site from 16th November to 16th December in 2018, the influences of SA formation on CCN activity and CCN number concentration (NCCN) calculation under different RH conditions were studied. Measurements showed that during daytime the SA formation can lead to a significant increase of NCCN and a strong diurnal variation of CCN activity. During periods with minimum RH higher than 50 % in daytime (high RH conditions), SA formation significantly contributed to the particle mass/size changes in wide particle size range of 150 nm to 1000 nm, and lead to the increase of NCCN in particle size range of 200 nm to 300 nm while increase of particle mass concentration mainly in particle size larger than 300 nm. During periods with minimum RH lower than 30 % in daytime (low RH conditions), SA formation mainly contributed to the particle mass/size changes in particle size smaller than 300 nm and so did the increases of both NCCN and particle mass concentration. As a result, upon the same amount of mass increase through SA formation, the increase of NCCN is weaker under high RH conditions while stronger under low RH conditions. Moreover, the diurnal variations of aerosol mixing state (inferred from CCN measurements) due to SA formation was different under different RH conditions, which contributed one of the largest uncertainties in NCCN predictions. By applying aerosol mixing state estimated by number fraction of hygroscopic particles from measurements of particle hygroscopicity or mass fraction of SA from measurements of particle chemical compositions, the NCCN prediction was largely improved with relative deviations smaller than 30 %. This study highlights the impact of SA formation on CCN activity and NCCN calculation, which is of great significance for improving parameterization of SA formation in chemical-transport models and CCN predictions in climate models.

scholarly journals Role of ambient ammonia in particulate ammonium formation at a rural site in the North China Plain

2018 ◽  
Vol 18 (1) ◽  
pp. 167-184 ◽  
Author(s):  
Zhaoyang Meng ◽  
Xiaobin Xu ◽  
Weili Lin ◽  
Baozhu Ge ◽  
Yulin Xie ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Water Soluble ◽  
Precipitation Event ◽  
Rural Site ◽  
The North ◽  
The North China Plain ◽  
Hourly Data ◽  
The Impact ◽  
Particulate Ammonium

Abstract. The real-time measurements of NH3 and trace gases were conducted, in conjunction with semi-continuous measurements of water-soluble ions in PM2.5 at a rural site in the North China Plain (NCP) from May to September 2013 in order to better understand chemical characteristics of ammonia and the impact of secondary ammonium aerosols on formation in the NCP. Extremely high NH3 and NH4+ concentrations were observed after a precipitation event within 7–10 days following urea application. Elevated NH3 levels coincided with elevated NH4+, indicating that NH3 likely influenced particulate ammonium mass. For the sampling period, the average conversion ∕ oxidation ratios for NH4+ (NHR), SO42- (SOR), and NO3- (NOR) were estimated to be 0.30, 0.64, and 0.24, respectively. The increased NH3 concentrations, mainly from agricultural activities and regional transport, coincided with the prevailing meteorological conditions. The high NH3 level with NHR of about 0.30 indicates that the emission of NH3 in the NCP is much higher than needed for aerosol acid neutralisation, and NH3 plays an important role in the formation of secondary aerosols as a key neutraliser. The hourly data obtained were used to investigate gas–aerosol partitioning characteristics using the thermodynamic equilibrium model ISORROPIA-II. Modelled SO42-, NO3-, and NH3 values agree well with the measurements, while the modelled NH4+ values largely underestimate the measurements. Our observation and modelling results indicate that strong acids in aerosol are completely neutralised. Additional NH4+ exists in aerosol, probably a result of the presence of a substantial amount of oxalic and other diacids.

scholarly journals Impact of crop field burning and mountains on heavy haze in the North China Plain: A case study

2016 ◽  
Author(s):  
X. Long ◽  
X. X. Tie ◽  
J. J. Cao ◽  
R. J. Huang ◽  
T. Feng ◽  
...  
Keyword(s):  
Air Pollution ◽  
North China Plain ◽  
North China ◽  
Wind Condition ◽  
Beijing City ◽  
The North ◽  
The North China Plain ◽  
Crop Field ◽  
The Impact ◽  
Field Burning

Abstract. Crop field burning (CFB) has important effects on air pollution in China, but it is seldom quantified and reported in a regional scale, which is of great importance for the control strategies of CFB in China, especially in the North China Plain (NCP). With the provincial statistical data and open crop fires captured by satellite (MODIS), we extracted a detailed emission inventory of CFB during a heavy haze event from 6th to 12th October 2014. A regional dynamical and chemical model (WRF-Chem) was applied to investigate the impact of CFB on air pollution in NCP. The model simulations were compared with the in situ measurements of PM2.5 (particular matter with radius less than 2.5 μm) concentrations. The model evaluation shows that the correlation coefficients (R) between measured and calculated values exceeds 0.80 and absolute normalized mean bias (NMB) is no more than 14 %. In addition, the simulated meteorological parameters such as winds and planetary boundary layer height (PBLH) are also in good agreement with observations. The model was intensive used to study (1) the impacts of CFB and (2) the effect of mountains on regional air quality. The results show that the CFB occurred in southern NCP (SNCP) had significant effect on PM2.5 concentrations locally, causing a maximum of 35 % PM2.5 increase in SNCP. Because of south wind condition, the CFB pollution plume is subjective a long transport to northern NCP (NNCP-with several mega cities, including Beijing of the capital city in China), where there are no significant CFB occurrences, causing a maximum of 32 % PM2.5 increase in NNCP. As a result, the heavy haze in Beijing is enhanced by the CFB occurred in SNCP. Further more, there are two major mountains located in the western and northern NCP. Under the south wind condition, these mountains play important roles in enhancing the PM2.5 pollution in NNCP through the blocking and guiding effects. This study suggests that the PM2.5 emissions in SNCP region should be significantly limited in order to reduce the occurrences of heavy haze events in NNCP region, including the Beijing City.

scholarly journals Summertime fine particulate nitrate pollution in the North China Plain: Increasing trends, formation mechanisms, and implications for control policy

2018 ◽  
Author(s):  
Liang Wen ◽  
Likun Xue ◽  
Xinfeng Wang ◽  
Caihong Xu ◽  
Tianshu Chen ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Fine Particles ◽  
Nitrate Pollution ◽  
Effective Control ◽  
Formation Mechanisms ◽  
The North ◽  
The North China Plain ◽  
Holistic Understanding ◽  
Nitrate Aerosol

Abstract. Nitrate aerosol composes a significant fraction of fine particles and plays a key role in regional air quality and climate. To obtain a holistic understanding of the nitrate pollution and its formation mechanisms over the North China Plain (NCP) – the most industrialized and polluted region in northern China, intensive field observations were conducted at three sites during summertime in 2014–2015. The measurement sites include the downtown and downwind of Ji'nan, the capital city of Shandong Province, as well as the peak of NCP – Mt. Tai (1534 m a.s.l.), and hence cover representative urban, rural and remote areas of the region. Elevated nitrate concentrations were observed at all three sites despite distinct temporal and spatial variations. The nitrate / PM2.5 and nitrate / sulfate ratios have significantly increased in Ji'nan (2005–2015) and at Mt. Tai (from 2007 to 2014), indicating the worsening situation of regional nitrate pollution. A multi-phase chemical box model (RACM/CAPRAM) was deployed and constrained by observations to elucidate the nitrate formation mechanisms. The principal formation route is the partitioning of gaseous HNO3 to aerosol phase at daytime, whilst the nocturnal nitrate formation is dominated by the heterogeneous hydrolysis of N2O5. The daytime nitrate production in the NCP region is mainly limited by the availability of NO2 and to a lesser extent O3 and NH3, and the nighttime formation is controlled by both NO2 and O3. NH3 prompts significantly the nitrate formation at daytime but plays a slightly negative role in the nighttime. Our analyses suggest that controlling NOx and O3 is an efficient way at the moment to mitigate nitrate pollution in the NCP region, where NH3 is usually in excess in summer. This study provides observational evidence of rising trend of nitrate aerosol as well as scientific support for formulating effective control strategies for regional haze in China.

Sign in / Sign up

Export Citation Format

Share Document