scholarly journals Characteristics of aerosol pollution during heavy haze events in Suzhou, China

2016 ◽  
Vol 16 (11) ◽  
pp. 7357-7371 ◽  
Author(s):  
Mi Tian ◽  
Huanbo Wang ◽  
Yang Chen ◽  
Fumo Yang ◽  
Xiaohua Zhang ◽  
...  
Keyword(s):  
Gas Phase ◽  
Inorganic Ions ◽  
Weather Conditions ◽  
Water Soluble ◽  
Chemical Components ◽  
Formation Mechanisms ◽  
Visibility Impairment ◽  
Aerosol Pollution ◽  
Haze Formation ◽  
High Concentrations

Abstract. Extremely severe haze weather events occurred in many cities in China, especially in the east part of the country, in January 2013. Comprehensive measurements including hourly concentrations of PM2.5 and its major chemical components (water-soluble inorganic ions, organic carbon (OC), and elemental carbon (EC)) and related gas-phase precursors were conducted via an online monitoring system in Suzhou, a medium-sized city in Jiangsu province, just east of Shanghai. PM2.5 (particulate matter with an aerodynamic diameter of 2.5 µm or less) frequently exceeded 150 µg m−3 on hazy days, with the maximum reaching 324 µg m−3 on 14 January 2013. Unfavorable weather conditions (high relative humidity (RH), and low rainfall, wind speed, and atmospheric pressure) were conducive to haze formation. High concentrations of secondary aerosol species (including SO42−, NO3−, NH4+, and SOC) and gaseous precursors were observed during the first two haze events, while elevated primary carbonaceous species emissions were found during the third haze period, pointing to different haze formation mechanisms. Organic matter (OM), (NH4)2SO4, and NH4NO3 were found to be the major contributors to visibility impairment. High concentrations of sulfate and nitrate might be explained by homogeneous gas-phase reactions under low RH conditions and by heterogeneous processes under relatively high RH conditions. Analysis of air mass trajectory clustering and potential source contribution function showed that aerosol pollution in the studied areas was mainly caused by local activities and surrounding sources transported from nearby cities.

scholarly journals Characteristics of aerosol pollution during heavy haze events in Suzhou, China

2015 ◽  
Vol 15 (22) ◽  
pp. 33407-33443 ◽  
Author(s):  
M. Tian ◽  
H. B. Wang ◽  
Y. Chen ◽  
F. M. Yang ◽  
X. H. Zhang ◽  
...  
Keyword(s):  
Gas Phase ◽  
Inorganic Ions ◽  
Water Soluble ◽  
Heterogeneous Reactions ◽  
Light Extinction ◽  
High Concentration ◽  
Aerosol Composition ◽  
Haze Pollution ◽  
Visibility Impairment ◽  
Aerosol Pollution

Abstract. A comprehensive measurement was carried out to analyze the heavy haze events in Suzhou in January 2013 when extremely severe haze pollution occurred in many cities in China especially in the East. Hourly concentrations of PM2.5, chemical composition (including water-soluble inorganic ions, OC, and EC), and gas-phase precursors were obtained via on-line monitoring system. Based on these data, detailed aerosol composition, light extinction and gas-phase precursors were analyzed to understand the characteristics of the haze events, moreover, the formation mechanism of nitrate and sulfate in PM2.5 and the regional sources deduced from trajectory and PSCF were discussed to explore the origin of the heavy aerosol pollution. The results showed that frequent haze events were occurred on January 2013 and the concentrations of PM2.5 often exceeded 150 μg m-3 during the haze occurrence, with a maximum concentration of 324 μg m-3 on 14 January 2013. Unfavorable weather conditions (high RH, and low rainfall, wind speed and atmospheric pressure), high concentration of secondary aerosol species (including SO42-, NO3-, NH4+, and SOC) and precursors were observed during the haze events. Additionally, OM, (NH4)2SO4, NH4NO3 were demonstrated to be the major contributors to the visibility impairment but the share differed from haze events. This study also found that the high concentration of sulfate might be explained by the heterogeneous reactions in the aqueous surface layer of pre-existing particles or in cloud processes while nitrate might be mainly formed through homogeneous gas-phase reactions. The results of trajectory clustering and the PSCF method manifested that aerosol pollutions in the studied areas were mainly affected by local activities and surrounding sources transported from nearby cities.

scholarly journals Characteristics of PM2.5 Chemical Compositions and Their Effect on Atmospheric Visibility in Urban Beijing, China during the Heating Season

2018 ◽  
Vol 15 (9) ◽  
pp. 1924 ◽  
Author(s):  
Xing Li ◽  
Shanshan Li ◽  
Qiulin Xiong ◽  
Xingchuan Yang ◽  
Mengxi Qi ◽  
...  
Keyword(s):  
Fine Particles ◽  
Inorganic Ions ◽  
Water Soluble ◽  
Motor Vehicles ◽  
Urban Site ◽  
Chemical Compositions ◽  
Heating Season ◽  
Atmospheric Visibility ◽  
Visibility Impairment ◽  
Mass Concentrations

Beijing, which is the capital of China, suffers from severe Fine Particles (PM2.5) pollution during the heating season. In order to take measures to control the PM2.5 pollution and improve the atmospheric environmental quality, daily PM2.5 samples were collected at an urban site from 15 November to 31 December 2016, characteristics of PM2.5 chemical compositions and their effect on atmospheric visibility were analyzed. It was found that the daily average mass concentrations of PM2.5 ranged from 7.64 to 383.00 μg m−3, with an average concentration of 114.17 μg m−3. On average, the Organic Carbon (OC) and Elemental Carbon (EC) contributed 21.39% and 5.21% to PM2.5, respectively. Secondary inorganic ions (SNA: SO42− + NO3− + NH4+) dominated the Water-Soluble Inorganic Ions (WSIIs) and they accounted for 47.09% of PM2.5. The mass concentrations of NH4+, NO3− and SO42− during the highly polluted period were 8.08, 8.88 and 6.85 times greater, respectively, than during the clean period, which contributed most to the serious PM2.5 pollution through the secondary transformation of NO2, SO2 and NH3. During the highly polluted period, NH4NO3 contributed most to the reconstruction extinction coefficient (b′ext), accounting for 35.7%, followed by (NH4)2SO4 (34.44%) and Organic Matter (OM: 15.24%). The acidity of PM2.5 in Beijing was weakly acid. Acidity of PM2.5 and relatively high humidity could aggravate PM2.5 pollution and visibility impairment by promoting the generation of secondary aerosol. Local motor vehicles contributed the most to NO3−, OC, and visibility impairment in urban Beijing. Other sources of pollution in the area surrounding urban Beijing, including coal burning, agricultural sources, and industrial sources in the Hebei, Shandong, and Henan provinces, released large amounts of SO2, NH3, and NO2. These, which were transformed into SO42−, NH4+, and NO3− during the transmission process, respectively, and had a great impact on atmospheric visibility impairment.

scholarly journals Insight into winter haze formation mechanisms based on aerosol hygroscopicity and effective density measurements

2017 ◽  
Author(s):  
Yuanyuan Xie ◽  
Xingnan Ye ◽  
Zhen Ma ◽  
Ye Tao ◽  
Ruyu Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Growth ◽  
Water Soluble ◽  
Effective Density ◽  
Pollution Level ◽  
Formation Mechanisms ◽  
Haze Pollution ◽  
Haze Formation

Abstract. We characterize a representative haze event from a series of periodic particulate matter (PM) episodes that occurred in Shanghai during winter 2014. Particle size distribution, hygroscopicity, and effective density were measured online, along with analysis of water-soluble inorganic ions and single particle mass spectrometry. Regardless of pollution level, the mass ratio of SNA/PM1.0 (sulfate, nitrate, and ammonium) slightly fluctuated around 0.28 over the whole observation, suggesting that both secondary inorganic compounds and carbonaceous aerosols (including soot and organic matter) contributed substantially to the haze formation. Nitrate was the most abundant ionic species during hazy periods, indicating that NOx contributed more to haze formation in Shanghai than did SO2. The calculated PM concentration from particle size distribution displayed a variation pattern similar to that of measured PM1.0 during the representative PM episode, indicating that enhanced pollution level was attributable to the elevated number of larger particles. The number fraction of the near-hydrophobic group increased as the PM episode developed, indicating accumulation of local emissions. Three "banana-shape" particle evolutions were consistent with the rapid increase in PM1.0 mass loading, indicating rapid size growth by condensation of condensable materials was responsible for the severe haze formation. Both hygroscopicity and effective density of the particles increased considerably with growing particle size during the banana-shaped evolutions, indicating that secondary transformation of NOx and SO2 was a major contributor to the particle growth. Our results suggest that the accumulation of gas-phase and particulate pollutants under stagnant meteorological conditions and subsequent rapid particle growth by secondary processes, were primarily responsible for the haze pollution in Shanghai during wintertime.

scholarly journals Insight into winter haze formation mechanisms based on aerosol hygroscopicity and effective density measurements

2017 ◽  
Vol 17 (11) ◽  
pp. 7277-7290 ◽  
Author(s):  
Yuanyuan Xie ◽  
Xingnan Ye ◽  
Zhen Ma ◽  
Ye Tao ◽  
Ruyu Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Inorganic Compounds ◽  
Particle Growth ◽  
Water Soluble ◽  
Effective Density ◽  
Pollution Level ◽  
Formation Mechanisms ◽  
Haze Pollution ◽  
Shaped Particle ◽  
Haze Formation

Abstract. We characterize a representative particulate matter (PM) episode that occurred in Shanghai during winter 2014. Particle size distribution, hygroscopicity, effective density, and single particle mass spectrometry were determined online, along with offline analysis of water-soluble inorganic ions. The mass ratio of SNA ∕ PM1. 0 (sulfate, nitrate, and ammonium) fluctuated slightly around 0.28, suggesting that both secondary inorganic compounds and carbonaceous aerosols contributed substantially to the haze formation, regardless of pollution level. Nitrate was the most abundant ionic species during hazy periods, indicating that NOx contributed more to haze formation in Shanghai than did SO2. During the representative PM episode, the calculated PM was always consistent with the measured PM1. 0, indicating that the enhanced pollution level was attributable to the elevated number of larger particles. The number fraction of the near-hydrophobic group increased as the PM episode developed, indicating the accumulation of local emissions. Three banana-shaped particle evolutions were consistent with the rapid increase of PM1. 0 mass loading, indicating that the rapid size growth by the condensation of condensable materials was responsible for the severe haze formation. Both hygroscopicity and effective density of the particles increased considerably with growing particle size during the banana-shaped evolutions, indicating that the secondary transformation of NOx and SO2 was one of the most important contributors to the particle growth. Our results suggest that the accumulation of gas-phase and particulate pollutants under stagnant meteorological conditions and subsequent rapid particle growth by secondary processes were primarily responsible for the haze pollution in Shanghai during wintertime.

scholarly journals Seasonal and diurnal characteristics of water soluble inorganic compounds in the gas and aerosol phase in the Zurich area

2005 ◽  
Vol 5 (4) ◽  
pp. 5809-5839 ◽  
Author(s):  
R. Fisseha ◽  
J. Dommen ◽  
L. Gutzwiller ◽  
E. Weingartner ◽  
M. Gysel ◽  
...  
Keyword(s):  
Gas Phase ◽  
Inorganic Compounds ◽  
Inorganic Ions ◽  
Water Soluble ◽  
Vehicle Emission ◽  
Mixing Ratios ◽  
Seasonal And Diurnal Variations ◽  
Water Soluble Inorganic Ions ◽  
Nocturnal Inversion ◽  
The City

Abstract. Gas and aerosol samples were taken using a wet effluent diffusion denuder/aerosol collector (WEDD/AC) coupled to ion chromatography (IC) in the city of Zurich, Switzerland from August to September 2002 and in March 2003. Major water soluble inorganic ions; nitrate, sulfate, and nitrite were analyzed online with a time resolution of two hours for the gas and aerosol phase. The fraction of water soluble inorganic anions in PM10 varied from 15% in August to about 38% in March. Seasonal and diurnal variations of nitrate in the gas and aerosol phase were observed with more than 50% of the total nitrate in the gas phase during August and more than 80% of nitrate in the aerosol phase during March exceeding the concentration of sulfate by a factor of 2. Aerosol sulfate, on the other hand, did not show significant variability with season. However, in the gas phase, the SO2 concentration was 6.5 times higher in winter than in summer. Nitrous acid (HONO) also showed a diurnal variation in both the gas and aerosol phase with the lowest concentration (0.2–0.6 µg/m3) in the afternoon. The primary pollutants, NO, CO and SO2 mixing ratios were often at their highest between 04:00–10:00 local time due to the build up of fresh vehicle emission under a nocturnal inversion.

scholarly journals Importance of Ammonia Gas-Particle Conversion Ratio in Haze Formation in the Rural Agricultural Environment

2020 ◽  
Author(s):  
Jian Xu ◽  
Jia Chen ◽  
Na Zhao ◽  
Guochen Wang ◽  
Guangyuan Yu ◽  
...  
Keyword(s):  
Fine Particles ◽  
Critical Role ◽  
Conversion Ratio ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Ammonia Gas ◽  
Haze Pollution ◽  
Inorganic Species ◽  
High Ammonia ◽  
Haze Formation

Abstract. Ammonia in the atmosphere is essential for the formation of fine particles that impact air quality and climate. Despite extensive prior research to disentangle the relationship between ammonia and haze pollution, the role of ammonia in haze formation in the high ammonia emitted regions is still not well understood. Aiming to better understand secondary inorganic aerosol (SNA) formation mechanisms under high ammonia conditions, one-year hourly measurement of water-soluble inorganic species (gas and particle) was conducted in a rural supersite in Shanghai. Exceedingly high levels of agricultural ammonia, constantly around 30 μg m−3, were observed. We find that ammonia gas-particle conversion ratio (ACR), as opposed to ammonia concentrations, plays a critical role in SNA formation during the haze period. By assessing the effects of various parameters, including temperature (T), aerosol water content (AWC), aerosol pH, and activity coefficient, it seems that AWC plays predominant regulating roles for ACR. We propose a self-amplifying feedback mechanism associated with ACR for the formation of SNA, which is consistent with diurnal variations of ACR, AWC, and SNA. Our results imply that reduction of ammonia emissions alone may not reduce SNA effectively at least in rural agricultural sites in China.

scholarly journals Heterogeneous Formation of Particulate Nitrate under Ammonium-rich Regime during the high PM<sub>2.5</sub> events in Nanjing, China

2019 ◽  
Author(s):  
Yu-Chi Lin ◽  
Yan-Lin Zhang ◽  
Mei-Yi Fan ◽  
Mengying Bao
Keyword(s):  
Inorganic Ions ◽  
Liquid Water Content ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Soluble Ions ◽  
Potential Formation ◽  
Nanjing City ◽  
Water Soluble Inorganic Ions ◽  
On Line ◽  
Heterogeneous Formation

Abstract. Particulate nitrate (NO3−) not only influences regional climates but also contributes to the acidification of terrestrial and aquatic ecosystems. In 2016 and 2017, four intensive on-line measurements of water-soluble ions in PM2.5 were conducted in Nanjing City to investigate the potential formation mechanisms of particulate nitrate. During the sampling periods, NO3− was the most predominant species, accounting for 35 % of the total water-soluble inorganic ions, followed by SO42− (33 %) and NH4+ (24 %). Significant enhancements of nitrate aerosols in terms of both absolute concentrations and relative abundances suggested that NO3− was a major contributing species to high-PM2.5 events (hourly PM2.5 ≥ 150 μg m−3). High NO3− concentrations mainly occurred under NH4+-rich conditions, implying that the formation of nitrate aerosols in Nanjing involved NH3. During the high-PM2.5 events, the nitrogen conversion ratios (Fn) were positively correlated with the aerosol liquid water content (ALWC, R = 0.75, p 

scholarly journals Formation and Evolution of Secondary Particulate Matter During Heavy Haze Pollution Episodes in Northeast China in Winter

2021 ◽  
Author(s):  
Ye Hong ◽  
Junying Sun ◽  
Yanjun Ma ◽  
YangFeng Wang ◽  
Xiaolan Li ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Gas Phase ◽  
Northeast China ◽  
Chemical Components ◽  
Common Mechanism ◽  
Formation Mechanisms ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Haze Pollution ◽  
Pollution Episodes

Abstract Based on the simultaneous observation of fine particulate matter (PM2.5) and its chemical components in four heavy haze pollution episodes at 14 sampling sites in northeast China from 2017 to 2019, the formation and existence of sulfate (SO42-) and nitrate (NO3-) secondary contaminants under different stages of the pollution episodes, and different meteorological and emission conditions were compared. The results yielded three main findings. (1) Organic carbon (OC) was the most important component of PM2.5, followed by NO3-,SO42-,and ammonium (NH4+). Nitrate surpassed sulfate as the most important secondary inorganic component over the study period. (2) The significant increase in atmospheric OC, SO42-, and NO3-concentrations was an important reason for haze formation. Meteorological factors such as wind direction, wind speed, temperature (T), relative humidity (RH), and atmospheric oxidability played an important role in secondary pollutant formation. (3) There were two potential SO42- formation mechanisms. The first was the gas-phase reaction of the hydroxyl radical(OH·) leading to the oxidation of nitrogen dioxide (NO2) and sulfur dioxide (SO2),and high ozone (O3) concentrations. A high atmospheric oxidability and high winter Ts were very important for SO42- formation. The second mechanism occurred under neutral or weakly alkaline conditions when large amounts of SO2 could enter aerosol droplets, and NO2 was more likely to react in the aqueous phase with SO2 to increase the output of SO42-. Nitrate formation was may be mainly due to the homogeneous gas-phase reaction of OH· with NO2, SO2, and ammonia(NH3). The highest NO3 concentration was observed under mild winter Ts, high RH, high atmospheric oxidability (O3 and nitrous acid (HONO)), high NH3 concentrations, and suitable light conditions. The differences in SO42- formation between northeast China and other regions were mainly a result of the suppression of the aqueous reaction of SO42- due to the low T in winter and low-sulfur coal emissions, which resulted in the gas-phase oxidation process with the highest SO42- production capacity becoming an important process. However, the aqueous reaction process was the most common mechanism of SO42- production in northeast China.

scholarly journals Importance of gas-particle partitioning of ammonia in haze formation in the rural agricultural environment

2020 ◽  
Vol 20 (12) ◽  
pp. 7259-7269 ◽  
Author(s):  
Jian Xu ◽  
Jia Chen ◽  
Na Zhao ◽  
Guochen Wang ◽  
Guangyuan Yu ◽  
...  
Keyword(s):  
Fine Particles ◽  
Critical Role ◽  
Feedback Mechanism ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Haze Pollution ◽  
Inorganic Species ◽  
High Ammonia ◽  
Haze Formation

Abstract. Ammonia in the atmosphere is essential for the formation of fine particles that impact air quality and climate. Despite extensive prior research to disentangle the relationship between ammonia and haze pollution, the role of ammonia in haze formation in high ammonia-emitting regions is still not well understood. Aiming to better understand secondary inorganic aerosol (sulfate, nitrate, ammonium – SNA) formation mechanisms under high-ammonia conditions, 1-year hourly measurement of water-soluble inorganic species (gas and particle) was conducted at a rural supersite in Shanghai. Exceedingly high levels of agricultural ammonia, constantly around 30 µg m−3, were observed. We find that gas-particle partitioning of ammonia (ε(NH4+)), as opposed to ammonia concentrations, plays a critical role in SNA formation during the haze period. From an assessment of the effects of various parameters, including temperature (T), aerosol water content (AWC), aerosol pH, and activity coefficient, it seems that AWC plays predominant regulating roles for ε(NH4+). We propose a self-amplifying feedback mechanism associated with ε(NH4+) for the formation of SNA, which is consistent with diurnal variations in ε(NH4+), AWC, and SNA. Our results imply that a reduction in ammonia emissions alone may not reduce SNA effectively, at least at rural agricultural sites in China.

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