scholarly journals Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

2018 ◽  
Vol 18 (3) ◽  
pp. 1729-1743 ◽  
Author(s):  
Li-Ming Cao ◽  
Xiao-Feng Huang ◽  
Yuan-Yuan Li ◽  
Min Hu ◽  
Ling-Yan He
Keyword(s):  
Ambient Temperature ◽  
Southern China ◽  
Chemical Species ◽  
Urban Atmosphere ◽  
Chemical Components ◽  
Formation Mechanisms ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Measurement Results ◽  
High Volatility

Abstract. Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS) system was deployed to study the volatility of non-refractory submicron particulate matter (PM1) species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m−3, with organic aerosol (OA) being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR) of 0.57 at 50 ∘C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 ∘C), and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 ∘C), with an evaporation rate of 0.45 %∘C-1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF) for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass-burning OA (BBOA, 8.9 %), and two oxygenated OAs (OOAs): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 ∘C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99), which was not completely consistent with the sequence of their O ∕ C ratios. The high volatility of HOA implied that it had a high potential to be oxidized to secondary species in the gas phase. The aerosol volatility measurement results in this study provide useful parameters for the modeling work of aerosol evolution in China and are also helpful in understanding the formation mechanisms of secondary aerosols.

scholarly journals Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

2017 ◽  
Author(s):  
Li-Ming Cao ◽  
Xiao-Feng Huang ◽  
Yuan-Yuan Li ◽  
Min Hu ◽  
Ling-Yan He
Keyword(s):  
Southern China ◽  
Chemical Species ◽  
Urban Atmosphere ◽  
Chemical Components ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Aerosol Pollution ◽  
Mass Spectrometer System ◽  
Spectrometer System

Abstract. Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a TD-AMS (Thermo-Denuder – Aerosol Mass Spectrometer) system was deployed to study the volatility of non-refractory PM1 species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7 ± 20.1 μg m−3, with organics being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with an MFR (mass fraction remaining) of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C), and the volatility had a relatively linear correlation with the TD temperature (from 50 to 200 °C), with an evaporation rate of 0.45 %·°C1. Five subtypes of OA were resolved from total OAs by PMF for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass burning OA (BBOA, 8.9 %) and two oxygenated OAs (OOA): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA species presented different volatilities; the volatility sequence of OA factors at 50 °C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99). The volatility sequence of OA components suggested that HOA, rather than BBOA or COA, could be a potentially important source of LO-OOA through the oxidizing process of Evaporation – Oxidation in gas phase – Condensation. The results above can contribute to the understanding of the formation and ageing of submicron aerosols in the atmosphere and will help to constrain aerosol modelling inputs.

scholarly journals Properties of aerosols and formation mechanisms over southern China during the monsoon season

2016 ◽  
Author(s):  
Weihua Chen ◽  
Xuemei Wang ◽  
Jason Blake Cohen ◽  
Shengzhen Zhou ◽  
Zhisheng Zhang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Southern China ◽  
Monsoon Season ◽  
Sea Salt ◽  
Urban Site ◽  
Chemical Components ◽  
Formation Mechanisms

Abstract. Measurements of size-resolved aerosols from 0.25 to 18 μm were conducted at three sites (urban, suburban and background sites) and used in tandem with an atmospheric transport model to study the size distribution and formation of atmospheric aerosols in southern China during the monsoon season (May–June) in 2010. The mass distribution showed the majority of chemical components were found in the smaller size bins (< 2.5 μm). Sulfate, was found to be strongly correlated with aerosol water, and anti-correlated with atmospheric SO2, hinting at aqueous-phase reactions being the main formation pathway. Nitrate was the only major species that showed a bi-modal distribution at the urban site, and was dominated by the coarse mode in the other two sites, suggesting that an important component of nitrate formation is chloride depletion of sea salt transported from the South China Sea. In addition to these aqueous-phase reactions and interactions with sea salt aerosols, new particle formation, chemical aging, and long-range transport from upwind urban or biomass burning regions were also found to be important in at least some of the sights on some of the days. This work therefore summarizes the different mechanisms that significantly impact the aerosol chemical composition during the Monsoon over southern China.

scholarly journals Chemically-resolved aerosol volatility measurements from two megacity field studies

2009 ◽  
Vol 9 (18) ◽  
pp. 7161-7182 ◽  
Author(s):  
J. A. Huffman ◽  
K. S. Docherty ◽  
A. C. Aiken ◽  
M. J. Cubison ◽  
I. M. Ulbrich ◽  
...  
Keyword(s):  
Chemical Species ◽  
Methanesulfonic Acid ◽  
Field Studies ◽  
Ambient Aerosols ◽  
Aerosol Mass Spectrometer ◽  
Diurnal Cycles ◽  
Aerosol Mass ◽  
Rapid Temperature ◽  
A New Technique

Abstract. The volatilities of different chemical species in ambient aerosols are important but remain poorly characterized. The coupling of a recently developed rapid temperature-stepping thermodenuder (TD, operated in the range 54–230°C) with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) during field studies in two polluted megacities has enabled the first direct characterization of chemically-resolved urban particle volatility. Measurements in Riverside, CA and Mexico City are generally consistent and show ambient nitrate as having the highest volatility of any AMS standard aerosol species while sulfate showed the lowest volatility. Total organic aerosol (OA) showed volatility intermediate between nitrate and sulfate, with an evaporation rate of 0.6%·K−1 near ambient temperature, although OA dominates the residual species at the highest temperatures. Different types of OA were characterized with marker ions, diurnal cycles, and positive matrix factorization (PMF) and show significant differences in volatility. Reduced hydrocarbon-like OA (HOA, a surrogate for primary OA, POA), oxygenated OA (OOA, a surrogate for secondary OA, SOA), and biomass-burning OA (BBOA) separated with PMF were all determined to be semi-volatile. The most aged OOA-1 and its dominant ion, CO2+, consistently exhibited the lowest volatility, with HOA, BBOA, and associated ions for each among the highest. The similar or higher volatility of HOA/POA compared to OOA/SOA contradicts the current representations of OA volatility in most atmospheric models and has important implications for aerosol growth and lifetime. A new technique using the AMS background signal was demonstrated to quantify the fraction of species up to four orders-of-magnitude less volatile than those detectable in the MS mode, which for OA represent ~5% of the non-refractory (NR) OA signal. Our results strongly imply that all OA types should be considered semivolatile in models. The study in Riverside identified organosulfur species (e.g. CH3HSO3+ ion, likely from methanesulfonic acid), while both studies identified ions indicative of amines (e.g. C5H12N+) with very different volatility behaviors than inorganic-dominated ions. The oxygen-to-carbon ratio of OA in each ambient study was shown to increase both with TD temperature and from morning to afternoon, while the hydrogen-to-carbon ratio showed the opposite trend.

scholarly journals Insights into aerosol chemistry during the 2015 China victory day parade: results from simultaneous measurements at ground level and 260 m in Beijing

2016 ◽  
Author(s):  
Jian Zhao ◽  
Wei Du ◽  
Yingjie Zhang ◽  
Qingqing Wang ◽  
Chen Chen ◽  
...  
Keyword(s):  
Control Period ◽  
Ground Level ◽  
Meteorological Conditions ◽  
Formation Mechanisms ◽  
Aerosol Chemistry ◽  
Positive Matrix ◽  
Aerosol Mass Spectrometer ◽  
Inorganic Aerosols ◽  
Aerosol Mass ◽  
Emission Controls

Abstract. Strict emission controls were implemented in Beijing and adjacent provinces to ensure good air quality during the 2015 China victory day parade. Here we conducted synchronous measurements of submicron aerosols (PM1) at ground level and 260 m on a meteorological tower by using a High-Resolution Aerosol Mass Spectrometer and an Aerosol Chemical Speciation Monitor, respectively, in Beijing from 22 August to 30 September. Our results showed that the average PM1 concentrations are 19.3 and 14.8 µg m−3 at ground level and 260 m, respectively, during the control period (20 August–3 September), which are 57 % and 50 % lower than those after the control period (4–30 September). Organic aerosols (OA) dominated PM1 during the control period at both ground level and 260 m (55 % and 53 %, respectively), while its contribution showed substantial decreases (~ 40 %) associated with an increase in secondary inorganic aerosols (SIA) after the parade indicating a larger impact of emission controls on SIA than OA. Positive matrix factorization of OA further illustrated that primary OA (POA) showed similar decreases as secondary OA (SOA) at both ground level (40 % vs. 42 %) and 260 m (35 % vs. 36 %). However, we also observed significant changes in SOA composition. While the more oxidized SOA showed a large decrease by 75 %, the less oxidized SOA was comparable during (5.6 µg m−3) and after the control periods (6.5 µg m−3). Our results demonstrated that the changes in meteorological conditions and PM loadings have affected SOA formation mechanisms, and the photochemical production of fresh SOA was more important during the control period. By isolating the influences of meteorological conditions and footprint regions in polluted episodes, we found that regional emission controls on average reduced PM levels by 44–45 %, and the reductions were close among SIA, SOA and POA at 260 m, whereas primary species showed relatively more reductions (55–67 %) than secondary aerosol species (33 %–44 %) at ground level.

scholarly journals A missing source of aerosols in Antarctica – beyond long-range transport, phytoplankton, and photochemistry

2017 ◽  
Vol 17 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Michael R. Giordano ◽  
Lars E. Kalnajs ◽  
Anita Avery ◽  
J. Douglas Goetz ◽  
Sean M. Davis ◽  
...  
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Real Time ◽  
Mass Spectrometer ◽  
Formation Mechanisms ◽  
Second Phase ◽  
Austral Spring ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
The Antarctic

Abstract. Understanding the sources and evolution of aerosols is crucial for constraining the impacts that aerosols have on a global scale. An unanswered question in atmospheric science is the source and evolution of the Antarctic aerosol population. Previous work over the continent has primarily utilized low temporal resolution aerosol filters to answer questions about the chemical composition of Antarctic aerosols. Bulk aerosol sampling has been useful in identifying seasonal cycles in the aerosol populations, especially in populations that have been attributed to Southern Ocean phytoplankton emissions. However, real-time, high-resolution chemical composition data are necessary to identify the mechanisms and exact timing of changes in the Antarctic aerosol. The recent 2ODIAC (2-Season Ozone Depletion and Interaction with Aerosols Campaign) field campaign saw the first ever deployment of a real-time, high-resolution aerosol mass spectrometer (SP-AMS – soot particle aerosol mass spectrometer – or AMS) to the continent. Data obtained from the AMS, and a suite of other aerosol, gas-phase, and meteorological instruments, are presented here. In particular, this paper focuses on the aerosol population over coastal Antarctica and the evolution of that population in austral spring. Results indicate that there exists a sulfate mode in Antarctica that is externally mixed with a mass mode vacuum aerodynamic diameter of 250 nm. Springtime increases in sulfate aerosol are observed and attributed to biogenic sources, in agreement with previous research identifying phytoplankton activity as the source of the aerosol. Furthermore, the total Antarctic aerosol population is shown to undergo three distinct phases during the winter to summer transition. The first phase is dominated by highly aged sulfate particles comprising the majority of the aerosol mass at low wind speed. The second phase, previously unidentified, is the generation of a sub-250 nm aerosol population of unknown composition. The second phase appears as a transitional phase during the extended polar sunrise. The third phase is marked by an increased importance of biogenically derived sulfate to the total aerosol population (photolysis of dimethyl sulfate and methanesulfonic acid (DMS and MSA)). The increased importance of MSA is identified both through the direct, real-time measurement of aerosol MSA and through the use of positive matrix factorization on the sulfur-containing ions in the high-resolution mass-spectral data. Given the importance of sub-250 nm particles, the aforementioned second phase suggests that early austral spring is the season where new particle formation mechanisms are likely to have the largest contribution to the aerosol population in Antarctica.

scholarly journals In-cloud formation of secondary species in iron-containing particles

2019 ◽  
Vol 19 (2) ◽  
pp. 1195-1206 ◽  
Author(s):  
Qinhao Lin ◽  
Xinhui Bi ◽  
Guohua Zhang ◽  
Yuxiang Yang ◽  
Long Peng ◽  
...  
Keyword(s):  
Southern China ◽  
Formation Rate ◽  
Cloud Formation ◽  
Dust Particles ◽  
Cloud Droplets ◽  
Aerosol Mass Spectrometer ◽  
Secondary Species ◽  
Cloud Processing ◽  
Aerosol Mass ◽  
Combustion Sources

Abstract. The increase in secondary species through cloud processing potentially increases aerosol iron (Fe) bioavailability. In this study, a ground-based counterflow virtual impactor coupled with a real-time single-particle aerosol mass spectrometer was used to characterize the formation of secondary species in Fe-containing cloud residues (dried cloud droplets) at a mountain site in southern China for nearly 1 month during the autumn of 2016. Fe-rich, Fe-dust, Fe-elemental carbon (Fe-EC), and Fe-vanadium (Fe-V) cloud residual types were obtained in this study. The Fe-rich particles, related to combustion sources, contributed 84 % (by number) to the Fe-containing cloud residues, and the Fe-dust particles represented 12 %. The remaining 4 % consisted of the Fe-EC and Fe-V particles. It was found that above 90 % (by number) of Fe-containing particles had already contained sulfate before cloud events, leading to no distinct change in number fraction (NF) of sulfate during cloud events. Cloud processing contributed to the enhanced NFs of nitrate, chloride, and oxalate in the Fe-containing cloud residues. However, the in-cloud formation of nitrate and chloride in the Fe-rich type was less obvious relative to the Fe-dust type. The increased NF of oxalate in the Fe-rich cloud residues was produced via aqueous oxidation of oxalate precursors (e.g., glyoxylate). Moreover, Fe-driven Fenton reactions likely increase the formation rate of aqueous-phase OH, improving the conversion of the precursors to oxalate in the Fe-rich cloud residues. During daytime, the decreased NF of oxalate in the Fe-rich cloud residues was supposed to be due to the photolysis of Fe-oxalate complexes. This work emphasizes the role of combustion Fe sources in participating in cloud processing and has important implications for evaluating Fe bioavailability from combustion sources during cloud processing.

scholarly journals A technique for the measurement of organic aerosol hygroscopicity, oxidation level, and volatility distributions

2017 ◽  
Vol 10 (12) ◽  
pp. 4865-4876 ◽  
Author(s):  
Kerrigan P. Cain ◽  
Spyros N. Pandis
Keyword(s):  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Experimental Setup ◽  
Aerosol Mass Spectrometer ◽  
Oxidation Level ◽  
Aerosol Mass ◽  
Analysis Technique ◽  
Measurement And Analysis ◽  
High Volatility ◽  
Aerosol Hygroscopicity

Abstract. Hygroscopicity, oxidation level, and volatility are three crucial properties of organic pollutants. This study assesses the feasibility of a novel measurement and analysis technique to determine these properties and establish their relationship. The proposed experimental setup utilizes a cloud condensation nuclei (CCN) counter to quantify hygroscopic activity, an aerosol mass spectrometer to measure the oxidation level, and a thermodenuder to evaluate the volatility. The setup was first tested with secondary organic aerosol (SOA) formed from the ozonolysis of α-pinene. The results of the first experiments indicated that, for this system, the less volatile SOA contained species that had on average lower O : C ratios and hygroscopicities. In this SOA system, both low- and high-volatility components can have comparable oxidation levels and hygroscopicities. The method developed here can be used to provide valuable insights about the relationships among organic aerosol hygroscopicity, oxidation level, and volatility.

scholarly journals Insights into aerosol chemistry during the 2015 China Victory Day parade: results from simultaneous measurements at ground level and 260 m in Beijing

2017 ◽  
Vol 17 (4) ◽  
pp. 3215-3232 ◽  
Author(s):  
Jian Zhao ◽  
Wei Du ◽  
Yingjie Zhang ◽  
Qingqing Wang ◽  
Chen Chen ◽  
...  
Keyword(s):  
Control Period ◽  
Ground Level ◽  
Meteorological Conditions ◽  
Formation Mechanisms ◽  
Aerosol Chemistry ◽  
Positive Matrix ◽  
Aerosol Mass Spectrometer ◽  
Inorganic Aerosols ◽  
Aerosol Mass ◽  
Emission Controls

Abstract. Strict emission controls were implemented in Beijing and adjacent provinces to ensure good air quality during the 2015 China Victory Day parade. Here, we conducted synchronous measurements of submicron aerosols (PM1) at ground level and 260 m on a meteorological tower by using a high-resolution aerosol mass spectrometer and an aerosol chemical speciation monitor, respectively, in Beijing from 22 August to 30 September. Our results showed that the average PM1 concentrations are 19.3 and 14.8 µg m−3 at ground level and 260 m, respectively, during the control period (20 August–3 September), which are 57 and 50 % lower than those after the control period (4–30 September). Organic aerosols (OAs) dominated PM1 during the control period at both ground level and 260 m (55 and 53 %, respectively), while their contribution showed substantial decreases (∼  40 %) associated with an increase in secondary inorganic aerosols (SIAs) after the parade, indicating a larger impact of emission controls on SIA than OA. Positive matrix factorization of OA further illustrated that primary OA (POA) showed similar decreases as secondary OA (SOA) at both ground level (40 % vs. 42 %) and 260 m (35 % vs. 36 %). However, we also observed significant changes in SOA composition at ground level. While the more oxidized SOA showed a large decrease by 75 %, the less oxidized SOA was comparable during (5.6 µg m−3) and after the control periods (6.5 µg m−3). Our results demonstrated that the changes in meteorological conditions and PM loadings have affected SOA formation mechanisms, and the photochemical production of fresh SOA was more important during the control period. By isolating the influences of meteorological conditions and footprint regions in polluted episodes, we found that regional emission controls on average reduced PM levels by 44–45 %, and the reductions were close among SIA, SOA and POA at 260 m, whereas primary species showed relatively more reductions (55–67 %) than secondary aerosol species (33–44 %) at ground level.

scholarly journals Chemical composition and mass size distribution of PM<sub>1.0</sub> at an elevated site in central east China

2014 ◽  
Vol 14 (10) ◽  
pp. 15191-15218 ◽  
Author(s):  
Y. M. Zhang ◽  
X. Y. Zhang ◽  
J. Y. Sun ◽  
G. Y. Hu ◽  
X. J. Shen ◽  
...  
Keyword(s):  
Submicron Particles ◽  
East China ◽  
Chemical Components ◽  
Chemical Compositions ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Four Seasons ◽  
Mass Size ◽  
Rural Sites ◽  
Log Normal

Abstract. Size-resolved aerosol chemical compositions were measured continuously for one and half years with an aerosol mass spectrometer (AMS) to characterize the mass and size distributions (MSDs) of each component in bulk, fresh and aged submicron particles (approximately PM1.0) at Mountain Tai, an elevated site in Central East China (CEC) from June 2010 to January 2012. The majority of the regionally-dispersed aerosols were found to be contributed from short distance mixed aerosol, mostly from its south with organics and sulfate as the major components. The annual mean mass concentrations of organics, sulfate, nitrate, ammonium and chloride were 11.2, 9.2, 7.2, 5.8 and 0.95 μg m−3, respectively, which are much lower for organics and sulfate, and slightly lower for nitrate, ammonium and chloride than those at the nearby surface rural sites. High organics were observed for all four seasons, and the relatively fresh organic aerosol (OA) containing high proportion of less-photo chemically OA, were found from long-range transported aerosol from northwest. Semi-volatile and low-volatile oxidized OAs together contributed approximately 49%, 55% in spring and 72% and 51% in winter of total OA, showing at least 50% of OA can be attributable to SOA. Seasonally, the chemical components at the elevated site showed a "winter high and autumn low" pattern, with organics, sulfate and ammonium peaking in summer. Though no obvious differences of MSDs were seen for various chemical components in the planetary boundary layer (PBL) and free troposphere (FT), the concentrations were a factor of 5–7 higher in PBL than in FT. The averaged MSDs of particles between 30–1000 nm for organics, sulfate, nitrate, and ammonium are approximately log-normal with similar mass median diameters (MMDs) of 539, 585, 542, and 545 nm, respectively, which were slightly larger than those in ground sites within North China Plain (NCP). Obvious differences in MMDs were found between fresh and aged aerosols for sulfate and ammonium, with smaller increased size-factors for the Mt. Tai aerosols than those in less polluted areas. All these exhibit the relative aged and well-mixed aerosol observed.

Sign in / Sign up

Export Citation Format

Share Document