scholarly journals Observation of biogenic secondary organic aerosols in the atmosphere of a mountain site in central China: temperature and relative humidity effects

2013 ◽  
Vol 13 (22) ◽  
pp. 11535-11549 ◽  
Author(s):  
J. J. Li ◽  
G. H. Wang ◽  
J. J. Cao ◽  
X. M. Wang ◽  
R. J. Zhang
Keyword(s):  
Relative Humidity ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Sampling Period ◽  
Oxidation Products ◽  
Central China ◽  
Clear Trend ◽  
Small Peak ◽  
Aerosol Acidity ◽  
Fine Mode

Abstract. Secondary organic aerosols (SOA) derived from isoprene, pinene and caryophyllene were determined for PM10 and size-segregated (9-stages) aerosols collected at the summit (2060 m a.s.l.) of Mt. Hua, central China during the summer of 2009. Estimated concentrations of isoprene, α-/β-pinene and β-caryophyllene derived secondary organic carbon (SOC) are 81 ± 53, 29 ± 14 and 98 ± 53 ng m−3, accounting for 2.7 ± 1.0%, 0.8 ± 0.2% and 2.1 ± 1.0% of OC, respectively. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature (R=0.57–0.90). However, a decreasing trend of BSOA concentration with an increase in relative humidity (RH) was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. There was no significant correlation observed for the BSOA products and anthropogenic parameters (e.g. EC, SO42− and NO4−). Size distribution measurements showed that most of the determined BSOA are formed in the aerosol phase and enriched in the fine mode (<2.1 μm) except for cis-pinonic acid, which is formed in the gas phase and subsequently partitioned into aerosol phase and thus presents a bimodal pattern with a small peak in the fine mode and a large peak in the coarse mode (>2.1 μm).

scholarly journals Observation of biogenic secondary organic aerosols in the atmosphere of a mountain site in central China: temperature and relative humidity effects

2013 ◽  
Vol 13 (7) ◽  
pp. 17643-17674 ◽  
Author(s):  
J. J. Li ◽  
G. H. Wang ◽  
J. J. Cao ◽  
X. M. Wang ◽  
R. J. Zhang
Keyword(s):  
Relative Humidity ◽  
Fine Particles ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Sampling Period ◽  
Oxidation Products ◽  
Central China ◽  
Clear Trend ◽  
Aerosol Acidity ◽  
Fine Mode

Abstract. Secondary organic aerosols (SOA) derived from isoprene, pinene and caryophyllene were determined for PM10 and size-segregated (9-stage) aerosols collected at the summit (2060 m, a.s.l.) of Mt. Hua, central China during the summer of 2009. Concentrations of estimated isoprene, α-/β-pinene and β-caryophyllene derived SOC are 81± 53, 29 ± 14 and 98 ± 53 ng m−3, accounting for 2.7± 1.0%, 0.8 ± 0.2% and 2.1 ± 1.0% of OC, respectively. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature (R=0.57–0.90). However, a decreasing trend of BSOA concentration with an increase in relative humidity (RH) was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. Size distribution measurement showed that most of the determined isoprene derived SOA may form in aerosol phase and enriched in the fine mode (<2.1μm). 3-Hydroxyglutaric acid, 3-methyl-1,2,3-butanetricarboxylic acid and β-caryophyllinic acid are only presented in fine particles. However, cis-pinonic acid presents a large peak in the coarse mode (>2.1 μm) due to its highly volatile nature.

scholarly journals Understanding the anthropogenic influence on formation of biogenic secondary organic aerosols in Denmark via analysis of organosulfates and related oxidation products

2014 ◽  
Vol 14 (17) ◽  
pp. 8961-8981 ◽  
Author(s):  
Q. T. Nguyen ◽  
M. K. Christensen ◽  
F. Cozzi ◽  
A. Zare ◽  
A. M. K. Hansen ◽  
...  
Keyword(s):  
Organic Acids ◽  
Long Range ◽  
Secondary Organic Aerosols ◽  
Global Radiation ◽  
Organic Aerosols ◽  
Photochemical Reactions ◽  
Common Mechanism ◽  
Aerosol Acidity ◽  
Local Impacts ◽  
Concentration Levels

Abstract. Anthropogenic emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) may affect concentration levels and composition of biogenic secondary organic aerosols (BSOA) through photochemical reactions with biogenic organic precursors to form organosulfates and nitrooxy organosulfates. We investigated this influence in a field study from 19 May to 22 June, 2011 at two sampling sites in Denmark. Within the study, we identified a substantial number of organic acids, organosulfates and nitrooxy organosulfates in the ambient urban curbside and semi-rural background air. A high degree of correlation in concentrations was found among a group of specific organic acids, organosulfates and nitrooxy organosulfates, which may originate from various precursors, suggesting a common mechanism or factor affecting their concentration levels at the sites. It was proposed that the formation of those species most likely occurred on a larger spatial scale, with the compounds being long-range transported to the sites on the days with the highest concentrations. The origin of the long-range transported aerosols was investigated using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model in addition to modeled emissions of related precursors, including isoprene and monoterpenes using the global Model of Emissions of Gases and Aerosols from Nature (MEGAN) and SO2 emissions using the European Monitoring and Evaluation Program (EMEP) database. The local impacts were also studied by examining the correlation between selected species, which showed significantly enhanced concentrations at the urban curbside site and the local concentrations of various gases, including SO2, ozone (O3), NOx, aerosol acidity and other meteorological conditions. This investigation showed that an inter-play of the local parameters such as the aerosol acidity, NOx, SO2, relative humidity (RH), temperature and global radiation seemed to affect the concentration level of those species, suggesting the influence of aqueous aerosol chemistry. The local impacts, however, seemed minor compared to the regional impacts. The total concentrations of organosulfates and nitrooxy organosulfates, on average, contributed to approximately 0.5–0.8% of PM1 mass at the two sampling sites.

scholarly journals Physical state of 2-methylbutane-1,2,3,4-tetraol in pure and internally mixed aerosols

2018 ◽  
Vol 18 (21) ◽  
pp. 15841-15857 ◽  
Author(s):  
Jörn Lessmeier ◽  
Hans Peter Dette ◽  
Adelheid Godt ◽  
Thomas Koop
Keyword(s):  
Glass Transition ◽  
Relative Humidity ◽  
Oxidation Product ◽  
Secondary Organic Aerosols ◽  
Glassy State ◽  
Organic Aerosols ◽  
Lower Troposphere ◽  
Tropospheric Temperature ◽  
Transition Temperatures ◽  
Glass Transition Temperatures

Abstract. 2-Methylbutane-1,2,3,4-tetraol (hereafter named tetraol) is an important oxidation product of isoprene and can be considered as a marker compound for isoprene-derived secondary organic aerosols (SOAs). Little is known about this compound's physical phase state, although some field observations indicate that isoprene-derived secondary organic aerosols in the tropics tend to be in a liquid rather than a solid state. To gain more knowledge about the possible phase states of tetraol and of tetraol-containing SOA particles, we synthesized tetraol as racemates as well as enantiomerically enriched materials. Subsequently the obtained highly viscous dry liquids were investigated calorimetrically by differential scanning calorimetry revealing subambient glass transition temperatures Tg. We also show that only the diastereomeric isomers differ in their Tg values, albeit only by a few kelvin. We derive the phase diagram of water–tetraol mixtures over the whole tropospheric temperature and humidity range from determining glass transition temperatures and ice melting temperatures of aqueous tetraol mixtures. We also investigated how water diffuses into a sample of dry tetraol. We show that upon water uptake two homogeneous liquid domains form that are separated by a sharp, locally constrained concentration gradient. Finally, we measured the glass transition temperatures of mixtures of tetraol and an important oxidation product of α-pinene-derived SOA: 3-methylbutane-1,2,3-tricarboxylic acid (3-MBTCA). Overall, our results imply a liquid-like state of isoprene-derived SOA particles in the lower troposphere at moderate to high relative humidity (RH), but presumably a semisolid or even glassy state at upper tropospheric conditions, particularly at low relative humidity, thus providing experimental support for recent modeling calculations.

scholarly journals Overview of the field measurement campaign in Hyytiälä, August 2001 in the framework of the EU project OSOA

2004 ◽  
Vol 4 (3) ◽  
pp. 657-678 ◽  
Author(s):  
M. Boy ◽  
T. Petäjä ◽  
M. Dal Maso ◽  
Ü. Rannik ◽  
J. Rinne ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Ground Level ◽  
Oxidation Products ◽  
Particle Phase ◽  
Average Growth ◽  
Photo Oxidation ◽  
Nucleation Mode ◽  
Condensation Sink

Abstract. As part of the OSOA (Origin and formation of Secondary Organic Aerosols) project, two intensive field campaigns were conducted in Melpitz, Germany and Hyytiälä, Finland. This paper gives an overview of the measurements made during the Hyytiälä campaign, which was held between 1 and 16 August 2001. Various instrumental techniques were used to achieve physical and chemical characterisation of aerosols and to investigate possible precursor gases. During the OSOA campaign in Hyytiälä, particle formation was observed on three consecutive days at the beginning of the campaign (1 to 3 August 2001) and on three days later on. The investigation of the meteorological situation divided the campaign into two parts. During the first three days of August, relatively cold and clean air masses from northwest passed over the station (condensation sink – CS: <0.002 s-1, NOx: <0.5 ppb). Daily particle bursts of one fraction of the nucleation mode aerosols (3–10 nm) with number concentrations between 600–1200 particles cm-3 were observed. After this period, warmer and more polluted air from south-west to south-east arrived at the station (CS: 0.002–0.01 s-1, NOx: 0.5–4 ppb) and during these 13 days only three events were observed. These events were not as apparent as those that occurred during the earlier period of the campaign. The chemical analyses from different institutes of PM2, PM2.5 and PM10 particles confirmed the assumption that organic matter from the oxidation of various terpenes contributed to the formation of secondary organic aerosols (SOA). Concerning these conclusions among others, the ratio between formic (oxidation product of isoprene and monoterpenes by ozone) and acetic acid (increased by anthropogenic emissions) (ratio=1 to 1.5) and concentration of different carboxylic acids (up to 62 ngm-3) were investigated. Gas/particle partitioning of five photo-oxidation products from α- and β-pinene resulted in higher concentrations of pinonic, nor pinonic and pinic acids in the particle phase than in the gas phase, which indicates a preference to the particle phase for these compounds. The average growth factors (GF) from 100 nm particles in water vapour gave a diurnal pattern with a maximum during daytime and values between 1.2 and 1.7. On average, the amount of secondary organic carbon reached values around 19% of the sampled aerosols and we speculate that formation of SOA with the influence of photo-oxidation products from terpenes was the reason for the observed particle bursts during the campaign. However, correlations between the precursor gases or the favourable condensing species with the monitored nucleation mode particles were not found. For the investigated time period other factors like the condensation sink of newly formed particles to the pre-existing aerosols, temperature and solar irradiance seem to be more important steering parameters for the production of new aerosols. Another open question concerns the vertical distribution of the formation of SOA. For this reason measurements were conducted at different altitudes using a tethered balloon platform with particle sampling and particle counting equipment. They were incorporated with eddy covariance (EC) flux measurements made at 23 m above ground level. The results give first indications that production of new aerosols happens throughout the planetary boundary layer (PBL), whereby different parameters e.g. temperature, CS, solar irradiance or concentration of monoterpenes are responsible for the location of the vertical maximum.

Formation of secondary organic aerosols from isoprene and its gas-phase oxidation products through reaction with hydrogen peroxide

2004 ◽  
Vol 38 (25) ◽  
pp. 4093-4098 ◽  
Author(s):  
Magda Claeys ◽  
Wu Wang ◽  
Alina C Ion ◽  
Ivan Kourtchev ◽  
András Gelencsér ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Gas Phase ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Oxidation Products ◽  
Phase Oxidation ◽  
Gas Phase Oxidation

scholarly journals Physical state of 2-methylbutane-1,2,3,4-tetraol in pure and internally mixed aerosols

2018 ◽  
Author(s):  
Jörn Lessmeier ◽  
Hans Peter Dette ◽  
Adelheid Godt ◽  
Thomas Koop
Keyword(s):  
Glass Transition ◽  
Relative Humidity ◽  
Oxidation Product ◽  
Secondary Organic Aerosols ◽  
Glassy State ◽  
Organic Aerosols ◽  
Lower Troposphere ◽  
Tropospheric Temperature ◽  
Transition Temperatures ◽  
Glass Transition Temperatures

Abstract. 2-Methylbutane-1,2,3,4-tetraol (hereafter named tetraol) is an important oxidation product of isoprene and can be considered as a marker compound for isoprene-derived secondary organic aerosols (SOAs). Little is known about this compound’s physical phase state, although some field observations indicate that isoprene-derived secondary organic aerosols in the tropics tend to be in a liquid rather than a solid state. To gain more knowledge about the possible phase states of tetraol and of tetraol-containing SOA particles, we synthesized tetraol as racemates as well as enantiomerically enriched materials. Subsequently the obtained highly viscous dry liquids were investigated calorimetrically by differential scanning calorimetry revealing subambient glass transitions temperatures Tg. We also show that only the diastereomeric isomers differ in their Tg values, albeit only by a few kelvin. We derive the phase diagram of water/tetraol mixtures over the whole tropospheric temperature and humidity range from determining glass transition temperatures and ice melting temperatures of aqueous tetraol mixtures. We also investigated how water diffuses into a sample of dry tetraol. We show that upon water uptake two homogeneous liquid domains form that are separated by a sharp, locally constrained concentration gradient. Finally, we measured the glass transition temperatures of mixtures of tetraol and an important oxidation product of α-pinene-derived SOA: 3-methylbutane-1,2,3-tricaboxylic acid (3 MBTCA). Overall, our results imply a liquid-like state of isoprene-derived SOA particle in the lower troposphere at moderate to high relative humidity, but presumably a semisolid or even glassy state at upper tropospheric conditions, particularly at low relative humidity, thus providing experimental support for recent modelling calculations.

scholarly journals Mixing of secondary organic aerosols versus relative humidity

2016 ◽  
Vol 113 (45) ◽  
pp. 12649-12654 ◽  
Author(s):  
Qing Ye ◽  
Ellis Shipley Robinson ◽  
Xiang Ding ◽  
Penglin Ye ◽  
Ryan C. Sullivan ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Relative Humidity ◽  
Atmospheric Aerosols ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Particle Mass ◽  
Diffusion Limitations ◽  
Single Particle Mass Spectrometry ◽  
Single Well ◽  
Phase Chemistry

Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions.

Evaporation Kinetics of Laboratory-Generated Secondary Organic Aerosols at Elevated Relative Humidity

2014 ◽  
Vol 49 (1) ◽  
pp. 243-249 ◽  
Author(s):  
Jacqueline Wilson ◽  
Dan Imre ◽  
Josef Beránek ◽  
Manish Shrivastava ◽  
Alla Zelenyuk
Keyword(s):  
Relative Humidity ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Kinetics Of ◽  
Evaporation Kinetics

scholarly journals Aerosol acidity in a megacity with high ambient temperature and relative humidity of Central China: temporal variation, determining factors and pollution transition effect

2018 ◽  
Author(s):  
Mingming Zheng ◽  
Shaofei Kong ◽  
Jianguo Bao ◽  
Ke Xu ◽  
Shurui Zheng ◽  
...  
Keyword(s):  
Air Pollution ◽  
Relative Humidity ◽  
Ambient Temperature ◽  
Fine Particles ◽  
Water Soluble ◽  
Central China ◽  
High Time Resolution ◽  
High Humidity ◽  
Aerosol Acidity ◽  
Logarithmic Curve

Abstract. Aerosol acidity affects the chemical transformation of aerosols and subsequent haze formation. High resolution (1-h) observation of water-soluble inorganic ions in fine particles, gaseous pollutants, and meteorological parameters was conducted from September 2015 to August 2016 at Wuhan, a megacity of Central China with high relative humidity and ambient temperature, compared with north Chinese cities. By adopting thermodynamic model ISOROPPIA-II, the aerosol acidity for different time scales, pollution episodes, and air mass directions was calculated. Aerosols in Wuhan were moderate acidic, with pH averaged as 3.30 ± 0.49. The aerosol acidity was higher in July (pH as 2.64 ± 0.31), September (pH as 2.75 ± 0.30) and August (pH as 2.79 ± 0.29), and lower in January (pH as 3.77 ± 0.28) and March (pH as 3.70 ± 0.16). It decreased with the air pollution increasing, with the pH values of 3.07 ± 0.45, 3.63 ± 0.27 and 3.84 ± 0.22 for clean, transition and polluted episodes, respectively. The air masses in Wuhan transported from North China exhibited higher aerosol acidity, with pH averaged as 3.17–3.22. The unique environmental and meteorological conditions (high humidity, annual averaged RH as 0.74 ± 0.13) lead to excess ammonium (on average of 6.06 ± 4.51 μg m−3) and abundant aerosol water content (AWC, on average of 71.0 ± 82.8 μg m−3) in Wuhan, which can explain the lower PM2.5 acidity in Wuhan than other megacities of China. At lower AWC level (less than ~ 15 μg m−3), the particle pH showed a decreasing trend with AWC increased. When the AWC continuous increased from ~ 15 to ~ 380 μg m−3, there was an obvious increase of particle pH. Then no significant growth of pH was found when AWC was higher than ~ 380 μg m−3. With atmospheric RH increasing, the aerosol pH exhibited decreasing trend firstly and then increased, with the turning point RH as about 0.48. There was a logarithmic growth of aerosol pH with total NHx (NH3 + NH4+) increasing. From the fitted logarithmic curve, the aerosol pH of Wuhan was at the range of pH rapid growth stage with NHx increasing, indicating that the control of ammonia emission in Wuhan could be an effective way to reduce the aerosol pH and further mitigate air pollution. This paper firstly obtained the aerosol acidity properties at a megacity under abundant ammonium and high humidity with high time-resolution, which is an important supplementary for the current aerosol acidity research around the world.

Online analysis of secondary organic aerosols from OH-initiated photooxidation and ozonolysis of α-pinene, β-pinene, Δ3-carene and d-limonene by thermal desorption–photoionisation aerosol mass spectrometry

2017 ◽  
Vol 14 (2) ◽  
pp. 75 ◽  
Author(s):  
Wenzheng Fang ◽  
Lei Gong ◽  
Liusi Sheng
Keyword(s):  
Mass Spectrometry ◽  
Thermal Desorption ◽  
Mass Spectra ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Online Analysis ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry

Environmental contextSecondary organic aerosol, formed by oxidation of volatile precursors such as monoterpenes, is a major contributor to the total atmospheric organic aerosol. We focus on the online mass spectrometric analysis of the aerosol generated by oxidation products of four major monoterpenes in an environmental chamber. Numerous important monoterpene oxidation products were clearly observed and provided a direct comparison of the formation of biogenic secondary organic aerosols. AbstractWe present here thermal desorption–tunable vacuum ultraviolet time-of-flight photoionisation aerosol mass spectrometry (TD-VUV-TOF-PIAMS) for online analysis of biogenic secondary organic aerosols (BSOAs) formed from OH-initiated photooxidation and dark ozonolysis of α-pinene, β-pinene, Δ3-carene and d-limonene in smog chamber experiments. The ‘soft’ ionisation at near-threshold photon energies (≤10.5eV) used in this study permits direct measurement of the fairly clean mass spectra, facilitating molecular identification. The online BSOA mass spectra compared well with previous offline measurements and most of the important monoterpene oxidation products were clearly found in the online mass spectra. Oxidation products such as monoterpene-derived acids (e.g. pinic acid, pinonic acid, 3-caronic acid, limononic acid, limonalic acid), ketones (e.g. norpinone, limonaketone), aldehydes (e.g. caronaldehyde, norcaronaldehyde, limononaldehyde) and multifunctional organics (e.g. hydroxypinonaldehydes, hydroxy-3-caronic aldehydes, hydroxylimononic acid) were tentatively identified. The online TD-VUV-TOF-PIAMS mass spectra showed that the OH-initiated photooxidation and ozonolysis of the same monoterpenes produced some similar BSOA products; for example, 3-caric acid, 3-caronic acid, 3-norcaronic acid, 3-norcaralic acid, caronaldehyde and norcaronaldehyde were observed in both photooxidation and ozonolysis of Δ3-carene. However, they could be formed through different pathways. Some of the same products and isomers (e.g. 10-oxopinonic acid, pinonic acid, norpinic acid, hydroxyl pinonaldehyde, norpinonic acid, norpinone) were formed during the photooxidation and ozonolysis of α-pinene and β-pinene. However, several different BSOA products were generated in these photooxidation and ozonolysis reactions due to their different parent structures. The OH–monoterpene reaction generated higher-molecular-weight products than O3–monoterpene owing to multiple OH additions to the unsaturated carbon bond. The online observation of key BSOA products provided a direct comparison of BSOA formation among different monoterpenes and insights into the formation pathways in the OH-initiated photooxidation and ozonolysis of monoterpenes.

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