• Title/Summary/Keyword: Secondary organic aerosols

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Review of Viscosities and Phases of Biogenic Secondary Organic Aerosols (생물기원 이차유기에어로졸의 점성도와 상 규명에 관한 최근 연구 동향)

  • Song, Mijung
    • Journal of Korean Society for Atmospheric Environment
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    • v.32 no.4
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    • pp.349-359
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    • 2016
  • Researchers have traditionally assumed that aerosol particles containing secondary organic aerosols (SOAs) are to be in liquid state with low viscosity even at low relative humidity. However, recent measurements showed that SOAs can have high viscosity under certain conditions. Herein, new different techniques for measurements of viscosities of SOA particles are introduced. Moreover, laboratory studies for the viscosities and the phases of biogenic SOAs produced by ${\alpha}$-pinene, isoprene, limonene, and ${\beta}$-caryophyllene of atmospheric relevance are reviewed. Future studies for determination of the phases of atmospheric aerosol particles are also suggested.

Characteristics of Organic Carbon Species in Atmospheric Aerosol Particles at a Gwangju Area During Summer and Winter (여름 및 겨울철 광주지역 대기 에어로졸 입자의 유기탄소 특성)

  • Park, Seung-Shik;Hur, Jai-Young;Cho, Sung-Y.;Kim, Seung-J.;Kim, Young-Joon
    • Journal of Korean Society for Atmospheric Environment
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    • v.23 no.6
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    • pp.675-688
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    • 2007
  • To characterize organic and elemental carbon (OC and EC), and water-soluble organic carbon (WSOC) contents, daily $PM_{2.5}$ measurements were performed in August 2006 (summer) and Jan $11{\sim}Feb$ 12 2007 (winter) at an urban site of Gwangju. Daily size-segregated aerosol samples were also collected for WSOC analysis. No clear seasonal variations in EC and WSOC concentrations were observed, while seasonal differences in OC concentration, and OC/EC and WSOC/EC ratios were shown. The WSOC/OC ratio showed higher value in summer (0.56) than in winter (0.40), reflecting the greater enhancement of secondary WSOC formation at the site in summer. Secondary WSOC concentrations estimated using EC tracer method were in the range $0.0{\sim}2.1\;{\mu}g/m^3$ (average $0.42\;{\mu}g/m^3$) and $0.0{\sim}1.1\;{\mu}g/m^3\;(0.24\;{\mu}g/m^3)$, respectively, accounting for $0{\sim}51.6%$ (average 16.8%) and $0{\sim}52.5%$ (average 13.1 %) of the measured WSOC concentrations in summer and winter. Sometimes higher WSOC/OC ratio in winter than that in summer could be attributed to two reasons. One is that the stable atmospheric condition often appears in winter, and the prolonged residence time would strengthen atmospheric oxidation of volatile organic compounds. The other is that decrease of ambient temperature in winter would enhance the condensation of volatile secondary WSOC on pre-existing aerosols. In summertime, atmospheric aerosols and WSOC concentrations showed bimodal size distributions, peaking at the size ranges $0.32{\sim}0.56\;{\mu}m$ (condensation mode) and $3.2{\sim}5.6\;{\mu}m$ (coarse mode), respectively. During the wintertime, atmospheric aerosols showed a bimodal character, while WSOC concentrations showed a unimodal pattern. Size distributions of atmospheric aerosols and WSOC with a peak in the size range $0.32{\sim}0.56\;{\mu}m$ were observed for most of the measurement periods. On January 17, however, atmospheric aerosols and WOSC exhibited size distributions with modal peaks in the size range $1.0{\sim}1.8\;{\mu}m$, suggesting that the aerosol particles collected on that day could be expected to be more aged, i.e, longer residence time, than the aerosols at other sampling periods.

Measurement and Control of Hazardous PAHs Reaction Products (위해성 이차 PAHs 성분 측정 및 관리 방안)

  • Lee, Ji Yi;Hong, Ji Hyung;Jung, Chang Hoon;Kim, Yong Pyo
    • Particle and aerosol research
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    • v.9 no.2
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    • pp.111-125
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    • 2013
  • Among the hazardous air pollutions(HAPs), characteristics of secondary organic aerosols are not well understood. In this study, the current state for the measurement and analysis of representative secondary PAHs such as oxy-PAHs and nitro-PAHs are presented with the discussion of their toxicity. Also, further research directions for the secondary PAHs are suggested. It was found that the chemical reaction mechanisms and products of PAHs in the air are poorly identified and their toxicities are not well studied. Moreover ambient concentrations of those secondary PAHs are not well documented. Sampling methodologies of those secondary PAHs are similar with PAHs but the analytical protocols for those secondary PAHs are more complicated than PAHs. Future management directions are suggested along with future research directions.

Analysis of Organic Compounds in Ambient PM2.5 over Seoul using Thermal Desorption-comprehensive Two Dimensional Gas Chromatography-time of Flight Mass Spectrometry (TD-GCxGC-TOFMS) (Thermal Desorption-comprehensive Two Dimensional Gas Chromatography-time of Flight Mass Spectrometry (TD-GCxGC-TOFMS)을 이용한 서울 대기 중 PM2.5 유기성분 분석)

  • Lee, Ji-Yi;Lane, Douglas A.;Huh, Jong-Bae;Yi, Sung-Muk;Kim, Yong-Pyo
    • Journal of Korean Society for Atmospheric Environment
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    • v.25 no.5
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    • pp.420-431
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    • 2009
  • Characteristics and advantages of the thermal desorption-comprehensive two dimensional gas chromatography-time of flight mass spectrometry (TD-GCxGC-TOFMS) were discussed and the organic compound's analysis result was shown for the ambient $PM_{2.5}$ sample collected in Seoul, Korea. Over 10,000 individual organic compounds were separated from about $70{\mu}g$ of aerosols in a single procedure with no sample pre-treatment. Among them, around 300 compounds were identified and classified based on the mass fragmentation patterns and GCxGC retention times. Several aliphatic compounds groups such as alkanes, alkenes, cycloalkanes, alkanoic acids, and alkan-2-ones were identified as well as 72 PAH compounds including alkyl substituted compounds and 8 hopanes. In Seoul aerosol, numerous oxidized aromatic compounds including major components of secondary organic aerosols were observed. The inventory of organic compounds in $PM_{2.5}$ of Seoul, Korea suggested that organic aerosol were constituted by the compounds of primary source emission as well as the formation of secondary organic aerosols.

Characteristics of Carbonaceous Aerosols Measured at Gosan - Based on Analysis of Thermal Distribution by Carbon Analyzer and Organic Compounds by GCMS (제주도 고산지역 탄소 성분의 특성 분석 - 유기탄소의 열광학적 특성 및 유기성분 중심으로)

  • Bae, Min-Suk;Park, Seung-Shik;Kim, Young Joon
    • Journal of Korean Society for Atmospheric Environment
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    • v.29 no.6
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    • pp.722-733
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    • 2013
  • Ground-based measurements were conducted from August 25 to September 8 of 2011 for understanding characteristics of carbonaceous aerosols measured at Gosan. Chemical components and their sources were discussed by analysis of organic compounds with identification of primary and secondary products in particulate matter. Thus, organic carbon (OC) and elemental carbon (EC) based on the carbonaceous thermal distribution (CTD), which provides detailed carbon signature characteristics relative to analytical temperature, was used to improve the carbon fractionation of the analytical method. In addition, organic compounds by gas chromatography technique with the backward trajectories were discussed for characteristics of carbonaceous aerosols. Different air-masses were classified related to the OC thermal signatures and the organic molecular markers such as aromatic acids and PAHs. We concluded that the aging process was influenced by the long-range transport from East Sea area.

Pollution characteristics of PM2.5 observed during January 2018 in Gwangju (광주 지역에서 2018년 1월 측정한 초미세먼지의 오염 특성)

  • Yu, Geun-Hye;Park, Seung-Shik;Jung, Sun A;Jo, Mi Ra;Jang, Yu Woon;Lim, Yong Jae;Ghim, Young Sung
    • Particle and aerosol research
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    • v.15 no.3
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    • pp.91-104
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    • 2019
  • In this study, hourly measurements of $PM_{2.5}$ and its major chemical constituents such as organic and elemental carbon (OC and EC), and ionic species were made between January 15 and February 10, 2018 at the air pollution intensive monitering station in Gwangju. In addition, 24-hr integrated $PM_{2.5}$ samples were collected at the same site and analyzed for OC, EC, water-soluble OC (WSOC), humic-like substance (HULIS), and ionic species. Over the whole study period, the organic aerosols (=$1.6{\times}OC$) and $NO_3{^-}$ concentrations contributed 26.6% and 21.0% to $PM_{2.5}$, respectively. OC and EC concentrations were mainly attributed to traffic emissions with some contribution from biomass burning emissions. Moreover, strong correlations of OC with WSOC, HULIS, and $NO_3{^-}$ suggest that some of the organic aerosols were likely formed through atmospheric oxidation processes of hydrocarbon compounds from traffic emissions. For the period between January 18 and 22 when $PM_{2.5}$ pollution episode occurred, concentrations of three secondary ionic species ($=SO{_4}^{2-}+NO_3{^-}+NH_4{^+}$) and organic matter contributed on average 50.8 and 20.1% of $PM_{2.5}$, respectively, with the highest contribution from $NO_3{^-}$. Synoptic charts, air mass backward trajectories, and local meteorological conditions supported that high $PM_{2.5}$ pollution was resulted from long-range transport of haze particles lingering over northeastern China, accumulation of local emissions, and local production of secondary aerosols. During the $PM_{2.5}$ pollution episode, enhanced $SO{_4}^{2-}$ was more due to the long-range transport of aerosol particles from China rather than local secondary production from $SO_2$. Increasing rate in $NO_3{^-}$ was substantially greater than $NO_2$ and $SO{_4}^{2-}$ increasing rates, suggesting that the increased concentration of $NO_3{^-}$ during the pollution episode was attributed to enhanced formation of local $NO_3{^-}$ through heterogenous reactions of $NO_2$, rather than impact by long-range transportation from China.

Review of Recent Smog Chamber Studies for Secondary Organic Aerosol (스모그 챔버를 이용한 이차 초미세유기먼지의 최근 연구 동향)

  • Lim, Yong Bin;Lee, Seung-Bok;Kim, Hwajin;Kim, Jin Young;Bae, Gwi-Nam
    • Journal of Korean Society for Atmospheric Environment
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    • v.32 no.2
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    • pp.131-157
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    • 2016
  • A smog chamber has been an effective tool to study air quality, particularly secondary organic aerosol (SOA), which is typically formed by atmospheric oxidation of volatile organic compounds (VOCs). In controlled environments, smog chamber studies have validated atmospheric oxidation by identifying, quantifying and monitoring products with state-of-art instruments (e.g., aerosol mass spectrometer, scanning mobility particle sizer) and provided chemical insights of SOA formation by elucidating reaction mechanisms. This paper reviews types of smog chambers and the current state of smog chamber studies that have accomplished to find pathways of SOA formation, focusing on gas-particle partitioning of semivolatile products of VOC oxidation, heterogeneous reactions on aerosol surface, and aqueous chemistry in aerosol waters (e.g., cloud/fog droplets and wet aerosols). For future chamber studies, then, this paper discusses potential formation pathways of fine particles that East Asia countries (e.g., Korea and China) currently suffer from due to massive formation that gives rise to fatal health problems.

Comparison of Temperature and Light Intensity Effects on the Photooxidation of Toluene-NOx-Air Mixture (온도와 광도가 톨루엔-NOx-공기 혼합물의 광산화 반응에 미치는 영향의 비교)

  • Ju, Ok-Jung;Bae, Gwi-Nam;Choi, Ji-Eun;Lee, Seung-Bok;Ghim, Young-Sung;Moon, Kil-Choo;Yoon, Soon-Chang
    • Journal of Korean Society for Atmospheric Environment
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    • v.23 no.3
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    • pp.353-363
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    • 2007
  • To differentiate temperature effect from the light intensity effect on the formation of secondary products during the photooxidation of toluene-$NO_x$-air mixtures, steady-state air temperature was changed from $20^{\circ}C\;to\;33^{\circ}C$ at the same light intensity of $0.39min^{-1}$ in an indoor smog chamber. Smog chamber consisted of 64 blacklights and a $5.8m^3$ reaction bag made of Teflon film. Air temperature was controlled by an air-conditioning system. The starting time for rapid conversion of NO to $NO_2$ was slightly delayed with decreasing air temperature. In contrast to light intensity effect, the ozone formation time and the ozone production rate were insensitive to air temperature. Although the formation time for secondary organic aerosols was not changed, the particle number concentration increased with temperature. However, the newly formed secondary organic aerosol mass at lower temperature was higher than that at higher temperature. Since light intensity significantly affected the starting time and quantity of ozone and aerosol formation, it is considered that the temperature could contribute partly the quantity of aerosol formation during the photooxidation of toluene-$NO_x$-air mixtures.