scholarly journals Supplementary material to "Particulate matter (PM) episodes at a suburban site in Hong Kong: evolution of PM characteristics and role of photochemistry in secondary aerosol formation"

2016 ◽  
Author(s):  
Yi Ming Qin ◽  
Yong Jie Li ◽  
Hao Wang ◽  
Berto Paul Yok Long Lee ◽  
Dan Dan Huang ◽  
...  
Keyword(s):  
Hong Kong ◽  
Particulate Matter ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Supplementary Material ◽  
Suburban Site

scholarly journals Particulate matter (PM) episodes at a suburban site in Hong Kong: evolution of PM characteristics and role of photochemistry in secondary aerosol formation

2016 ◽  
Vol 16 (22) ◽  
pp. 14131-14145 ◽  
Author(s):  
Yi Ming Qin ◽  
Yong Jie Li ◽  
Hao Wang ◽  
Berto Paul Yok Long Lee ◽  
Dan Dan Huang ◽  
...  
Keyword(s):  
Hong Kong ◽  
Particulate Matter ◽  
Time Lag ◽  
Organic Aerosol ◽  
Meteorological Conditions ◽  
Aerosol Formation ◽  
Small Particles ◽  
Large Particles ◽  
Photochemical Aging ◽  
Suburban Site

Abstract. Episodes with high concentrations of particulate matter (PM) across the seasons were investigated during four 1-month campaigns at a suburban site in Hong Kong. High-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) measurements revealed that both regional transport and secondary formation contributed to high PM levels during the episodes at this site. Based on distinct meteorological conditions, episodes were categorized into three types: liquid water content (LWC), solar irradiance (IR), and long-range transport (LRT). Despite the difference in meteorological conditions, all episodes were characterized by a high fraction of sulfate (45–56 %) and organics (23–34 %). However, aerosols in LWC episodes were less aged, consisting of the lowest fraction of secondary organic aerosol (SOA) and the highest fraction of small particles. Large particles mixed internally while freshly formed small particles mixed externally in LWC episodes. Aerosols in LRT episodes, by contrast, were the most aged and consisted of the highest proportion of low-volatility oxygenated organic aerosol (LVOOA) and the lowest proportion of small particles. Both small and large particles mixed externally in LRT episodes. The highest proportion of semi-volatile oxygenated organic aerosol (SVOOA) and a medium proportion of small particles were observed in IR episodes. Both small and large particles were likely externally mixed during IR episodes. Furthermore, aerosols experienced the most dramatic size increase and diurnal variation, with a time lag between SVOOA and LVOOA and a gradual increase in carbon oxidation state (OSc ≈ 2 × O : C − H : C). Five out of 10 episodes were of the IR type, further reflecting the importance of this type of episode. The evolution of aerosol components in one particular episode of the IR type, which exhibited a clear land–sea breeze pattern, was examined in detail. Sulfate and SOA due to photochemical aging were very efficiently produced during the course of 6 h. The “less-oxidized” SOA (SVOOA) was initially formed at a higher rate than the “more-oxidized” SOA (LVOOA). The SVOOA transformed to LVOOA at the later stage of photochemical aging. This transformation was further supported by mass spectral analysis, which showed an increase in the most oxidized ion (CO2+) and decreases in moderately oxidized ones (C2H3O+, C3H3O+ and C3H5O+). By measuring the physical and chemical properties of PM in a highly time-resolved manner, the current study was able to demonstrate the dynamic and complex nature of PM transformation during high-PM episodes.

scholarly journals Particulate matter (PM) episodes at a suburban site in Hong Kong: evolution of PM characteristics and role of photochemistry in secondary aerosol formation

2016 ◽  
Author(s):  
Yi Ming Qin ◽  
Yong Jie Li ◽  
Hao Wang ◽  
Berto Paul Yok Long Lee ◽  
Dan Dan Huang ◽  
...  
Keyword(s):  
Hong Kong ◽  
Particulate Matter ◽  
Time Lag ◽  
Organic Aerosols ◽  
Meteorological Conditions ◽  
Aerosol Formation ◽  
Small Particles ◽  
Large Particles ◽  
Photochemical Aging ◽  
Suburban Site

Abstract. Episodes with high concentrations of particulate matter (PM) across the seasons were investigated during four one-month campaigns at a suburban site in Hong Kong. High-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) measurements revealed that both regional transport and secondary formation contributed to high PM levels during the episodes at this site. Based on distinct meteorological conditions, episodes were categorized into three types: liquid water content (LWC), solar irradiance (IR), and long-range transport (LRT). Despite the difference in meteorological conditions, all episodes were characterized by a high fraction of sulfate (45 %–56 %) and organics (23 %–34 %). However, aerosols in LWC episodes were less aged, consisting of the lowest fraction of secondary organics aerosols (SOA) and the highest fraction of small particles. Large particles mixed internally while freshly formed small particles mixed externally in LWC episodes. Aerosols in LRT episodes, by contrast, were the most aged and consisted of the highest proportion of low-volatility oxygenated organic aerosols (LVOOA) and the lowest proportion of small particles. Both small and large particles mixed externally in LRT episodes. The highest proportion of semi-volatile oxygenated organic aerosols (SVOOA) and a medium proportion of small particles were observed in IR episodes. Both small and large particles were likely externally mixed during IR episodes. Unlike in the other two types of episodes, in IR episodes aerosols experienced the most dramatic size increase and diurnal variation, with a time lag between SVOOA and LVOOA and a gradual increase in carbon oxidation state (OSc ≈ 2 × O : C – H : C). Five out of ten episodes were of the IR type, further reflecting the importance of this type of episode. The evolution of aerosol components in one particular episode of the IR type, which exhibited a clear land-sea breeze pattern, was examined in detail. Sulfate and SOA due to photochemical aging were very efficiently produced during the course of six hours. The “fresh” SOA (SVOOA) was initially formed at a higher rate than the “aged” SOA (LVOOA). The SVOOA transformed to LVOOA at the later stage of photochemical aging. This tranformation was further supported by mass spectral analysis, which showed an increase in the most oxidized ion (CO2+) and decreases in moderately oxidized ones (C2H3O+, C3H3O+ and C3H5O+). By measuring the physical and chemical properties of PM in a highly time-resolved manner, the current study was able to demonstrate the dynamic and complex nature of PM transformation during high-PM episodes.

scholarly journals Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

2019 ◽  
Author(s):  
Jing Duan ◽  
Ru-Jin Huang ◽  
Yongjie Li ◽  
Qi Chen ◽  
Yan Zheng ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Seasonal Variations ◽  
Chemical Speciation ◽  
Fine Particles ◽  
Large Fraction ◽  
Formation Mechanisms ◽  
Urban Air ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Atmospheric Processes

Abstract. Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable studies in recent years. To elucidate the seasonal variations of fine particles composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) combined with other online instruments were used to characterize the submicron particulate matter (diameter 

scholarly journals Influence of fuel ethanol content on primary emissions and secondary aerosol formation potential for a modern flex-fuel gasoline vehicle

2016 ◽  
Author(s):  
Hilkka Timonen ◽  
Panu Karjalainen ◽  
Erkka Saukko ◽  
Sanna Saarikoski ◽  
Päivi Aakko-Saksa ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Compounds ◽  
Fuel Ethanol ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Aerosol Mass ◽  
Ethanol Content ◽  
Flex Fuel ◽  
Primary Emissions

Abstract. The effect of fuel ethanol content (10 %, 85 %, 100 %) on primary emissions and on subsequent secondary aerosol formation was investigated for a EURO5 flex-fuel gasoline vehicle. Emissions were characterized during the New European Driving Cycle (NEDC) using a comprehensive setup of high time resolution instruments. Detailed chemical composition of exhaust particulate matter (PM) was studied using a soot particle aerosol mass spectrometer (SP-AMS) and secondary aerosol formation using a potential aerosol mass (PAM) chamber. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease of aromatic BTEX (benzene, toluene, ethylbenzene and xylenes) compounds was observed when the amount of ethanol in fuel increased. In regard to particles, largest primary particulate matter concentrations and potential to form secondary particles were measured for the E10 fuel (10 % ethanol). As the ethanol content of the fuel increased, a significant decrease in average primary particulate matter concentrations over the NEDC cycle was found, PM emissions being 0.45, 0.25 and 0.15 mg m−3 for E10, E85 and E100, respectively. Similarly, a clear decrease in secondary aerosol formation potential was observed with larger contribution of ethanol in fuel. Secondary to primary PM ratios were 13.4, and 1.5 for E10 and E85, respectively. For E100 a slight decrease in PM mass was observed after the PAM chamber, indicating that the PM produced by secondary aerosol formation was less than the PM lost via e.g. wall losses or degradation of POA in the chamber. For all fuel blends, the formed secondary aerosol consisted mostly of organic compounds. For E10 the contribution of organic compounds containing oxygen increased from 35 %, measured for primary organics, to 62 % after the PAM chamber. For E85 the contribution of organic compounds containing oxygen increased from 42 % (primary) to 57 % (after the PAM chamber), whereas for E100 the amount of oxidized organics remained the same (approximately 62 %) with the PAM chamber when compared to the primary emissions.

scholarly journals Unraveling the role of silicon in atmospheric aerosol secondary formation: A new conservative tracer for aerosol chemistry

2018 ◽  
Author(s):  
Dawei Lu ◽  
Jihua Tan ◽  
Xuezhi Yang ◽  
Xu Sun ◽  
Qian Liu ◽  
...  
Keyword(s):  
Formation Process ◽  
Aerosol Particles ◽  
Chemical Species ◽  
Accurate Estimation ◽  
Aerosol Formation ◽  
Aerosol Chemistry ◽  
Secondary Aerosol ◽  
Conservative Tracer ◽  
Secondary Aerosols

Abstract. Aerosol particles are ubiquitous in the atmosphere and affect the quality of human life through their climatic and health effects. The formation and growth of aerosol particles involve extremely complex reactions and processes. Due to limited research tools, the sources and chemistry of aerosols are still not fully understood, and until now they are normally investigated by using chemical species of secondary aerosols (e.g., NH4+, NO3-, SO42-, SOC) as tracers. Here we investigated the role of silicon (Si), a ubiquitous but relatively inert element, during the secondary aerosol formation process. We analyzed the correlation of Si in airborne fine particles (PM2.5) collected in Beijing—a typical pollution region—with the secondary chemical species and secondary particle precursors (e.g., SO2 and NOx). The total mass of Si in PM2.5 was found to be uncorrelated with the secondary aerosol formation process, which suggested that Si is a new conservative tracer for aerosol chemistry. This finding enables the accurate estimation of secondary aerosol contribution to PM2.5 by using Si as a single tracer rather than normally used multiple chemical tracers. In addition, we show that the correlation analysis of secondary aerosols with the Si isotopic composition of PM2.5 can further reveal the sources of the precursors of secondary aerosols. Therefore, Si may open a new method for aerosol chemistry studies and pollution control policy development.

scholarly journals Unraveling the role of silicon in atmospheric aerosol secondary formation: a new conservative tracer for aerosol chemistry

2019 ◽  
Vol 19 (5) ◽  
pp. 2861-2870 ◽  
Author(s):  
Dawei Lu ◽  
Jihua Tan ◽  
Xuezhi Yang ◽  
Xu Sun ◽  
Qian Liu ◽  
...  
Keyword(s):  
Formation Process ◽  
Aerosol Particles ◽  
Chemical Species ◽  
Accurate Estimation ◽  
Aerosol Formation ◽  
Aerosol Chemistry ◽  
Secondary Aerosol ◽  
Conservative Tracer ◽  
Secondary Aerosols

Abstract. Aerosol particles are ubiquitous in the atmosphere and affect the quality of human life through their climatic and health effects. The formation and growth of aerosol particles involve extremely complex reactions and processes. Due to limited research tools, the sources and chemistry of aerosols are still not fully understood, and until now have normally been investigated by using chemical species of secondary aerosols (e.g., NH4+, NO3-, SO42-, SOC) as tracers. Here we investigated the role of silicon (Si), an ubiquitous but relatively inert element, during the secondary aerosol formation process. We analyzed the correlation of Si in airborne fine particles (PM2.5) collected in Beijing – a typical pollution region – with the secondary chemical species and secondary particle precursors (e.g., SO2 and NOx). The total mass of Si in PM2.5 was found to be uncorrelated with the secondary aerosol formation process, which suggested that Si is a new conservative tracer for the amount of primary materials in PM2.5 and can be used to estimate the relative amount of secondary and primary compounds in PM2.5. This finding enables the accurate estimation of secondary aerosol contribution to PM2.5 by using Si as a single tracer rather than the commonly used multiple chemical tracers. In addition, we show that the correlation analysis of secondary aerosols with the Si isotopic composition of PM2.5 can further reveal the sources of the precursors of secondary aerosols. Therefore, Si may provide a new tool for aerosol chemistry studies.

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