Seung-Shik Park

Source identification of water-soluble organic aerosols at a roadway site using a positive matrix factorization analysis.

Daily PM2.5 measurements were carried out at a local roadway every sixth day from May 2011 to August 2013 to obtain seasonal quantitative information on the primary and secondary sources of two water-soluble organic carbon (WSOC) fractions. Filter samples were analyzed for OC, elemental carbon (EC), WSOC, hydrophilic and hydrophobic WSOC fractions (WSOC(HPI) and WSOC(HPO)), and ionic species. An XAD solid phase extraction method and a total organic carbon analyzer were used to isolate the two WSOC fractions and determine their amounts, respectively. The WSOC/OC and WSOC(HPI)/WSOC ratios were 0.62±0.13 and 0.47±0.14, respectively. Similar seasonal profiles in EC, OC, and WSOC concentrations were observed, with higher concentrations occurring in the cold season and lower concentrations in the warm season. However, opposite results were obtained in WSOC/OC and WSOC(HPI)/WSOC ratios, with the higher in the warm season and the lower in the cold season. Correlation analyses indicated that two WSOC fractions in winter were likely attributed to secondary formation processes, biomass burning (BB), and traffic emissions, while WSOC(HPI) observed in other seasons were associated with secondary formation processes similar to those of oxalate and secondary inorganic species. A positive matrix factorization (PMF) model was employed to investigate the sources of two WSOC fractions. PMF indicated that concentrations of WSOC fractions were affected by five sources: secondary NO3(-) related, secondary SO4(2-) and oxalate related, traffic emissions, BB emissions, and sea-salt. Throughout the study period, secondary organic aerosols were estimated to be the most dominant contributor of WSOC fractions, with higher contributions occurring in the warm seasons. The contribution of secondary aerosol formation processes (NO3(-) related+SO4(2-) and oxalate related) to WSOC(HPI) and WSOC(HPO) was on an average 56.2% (45.0-73.8%) and 47.7% (39.6-52.1%), respectively. The seasonal average contribution of WSOC(HPI) and WSOC(HPO) attributed to BB was 19.0% (14.3-25.3%) and 14.8% (7.2-19.5%), respectively, with higher fractions occurring in the fall and winter. Traffic sources contributed to WSOC(HPI) and WSOC(HPO) from 4.2 to 21.0% (an average of 11.6%) and from 7.9 to 32.3% (an average of 19.9%), respectively, with higher fractions in the fall and winter compared with the other seasons. During the study period, for an episode associated with high local O3 level (~110 ppbv) and high WSOC(HPI)/WSOC (0.80), secondary formation processes contributed 67.1% to WSOCHPI, and 72.6% to WSOC(HPO), respectively. However, for an episode associated with local and severe regional haze pollutions, contributions of secondary formation processes to WSOC fractions were observed to be low (32.4-43.1%), while traffic and BB emissions contributed 16.8% and 24.3% to WSOC(HPI), respectively, and 18.3% and 18.7% to WSOC(HPO), respectively. The PMF results suggest that the contribution of traffic emissions to concentrations of two WSOC fractions cannot be neglected at the studied roadway site.

Adsorption and desorption characteristics of 2-methyl-4-chlorophenoxyacetic acid onto activated carbon

Adsorption and desorption characteristics of the 2-methyl-4-chlorophenoxyacetic acid (MCPA) from aqueous solution onto the activated carbon (GAC, F-400) were studied. Adsorption equilibrium capacities of the MCPA increased with decreasing pH and temperature of the solution. Adsorption equilibrium of the MCPA could be represented by the Sips equation. The internal diffusion coefficients were determined by comparing the experimental concentration decay curves with those predicted from surface diffusion model and pore diffusion model. The adsorption model based on the linear driving force approximation (LDFA) was used for simulating the adsorption behavior of the MCPA in a fixed bed. Over ninety five percent desorption of the MCPA could be obtained using distilled water.

Chemical Characteristics and Formation Pathways of Humic Like Substances (HULIS) in PM 2.5 in an Urban Area

Little information on HUmic-Like Substances (HULIS) in ambient particulate matter has been reported yet in Korea. HULIS makes up a significant fraction of the water-soluble organic mass in the atmospheric aerosols and influence their water uptake properties. In this study 24-hr PM2.5 samples were collected between December 2013 and October 2014 at an urban site in Gwangju and analyzed for organic carbon (OC), elemental carbon (EC), watersoluble OC (WSOC), HULIS, and ionic species, to investigate possible sources and formation processes of HULIS. HULIS was separated using solid phase extraction method and quantified by total organic carbon analyzer. During the study period, HULIS concentration ranged from 0.19 to 5.65 μgC/m with an average of 1.83±1.22 μgC/m, accounting for on average 45% of the WSOC (12~73%), with higher in cold season than in warm season. Strong correlation of WSOC with HULIS (R = 0.91) indicates their similar chemical characteristics. On the basis of the relationships between HULIS and a variety of chemical species (EC, K, NO3-, SO4, and oxalate), it was postulated that HULIS observed during summer and winter were likely attributed to secondary formation and primary emissions from biomass burning (BB) and traffics. Stronger correlation of HULIS with K, which is a BB tracer, in winter (R = 0.81) than in summer (R = 0.66), suggests more significant contribution of BB emissions in winter to the observed HULIS. It is interesting to note that BB emissions may also have an influence on the HULIS in summer, but further study using levoglucosan that is a unique organic marker of BB emissions is required during summer. Higher correlation between HULIS and oxalate, which is mainly formed through cloud processing and/or photochemical oxidation processes, was found in the summer (R = 0.76) than in the winter (R = 0.63), reflecting a high fraction of secondary organic aerosol in the summer.

Investigation on a Haze Episode of Fine Particulate Matter using Semi-continuous Chemical Composition Data

In this study, semi-continuous measurements of mass, organic and elemental carbon (OC and EC), black carbon (BC), and ionic species concentrations were made for the period of April 03~13, 2012, at a South Area Supersite at Gwangju. Possible sources causing the high concentrations of major chemical species in observed during a haze episode were investigated. The measurement results, along with meteorological parameters, gaseous pollutants data, air mass back trajectory analyses and PSCF (potential source contribution function) results, were used to study the haze episode. Substantial enhancements of OC, EC, BC, , , , , and CO concentrations were closely associated with air masses coming from regions of forest fires in southeastern China, suggesting likely an impact of the forest fires. Also the PSCF maps for EC, OC, , and demonstrate further that the long-range transport of smoke plumes of forest fires detected over the southeastern China could be a possible source of haze phenomena observed at the site. Another possible source leading to haze formation was likely from photochemistry of precursor gases such as volatile organic compounds, , and , resulting in accumulation of secondary organic aerosol, and . Throughout the episode, local wind directions were between 200 and , where two industrial areas are situated, with moderate wind speeds of 3~5 m/s, resulting in highly elevated concentration of with a maximum of 15 ppb. The peak occurring in the afternoon hours coincided with maximum ambient temperature () and ozone concentration (~100 ppb), and were driven by photochemistry of . As a result, the pattern of variations in relation to wind direction, and concentrations, and the strong correlation between and (

Characteristics of Carbonaceous Aerosols Measured at Gosan - Based on Analysis of Thermal Distribution by Carbon Analyzer and Organic Compounds by GCMS

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Influence of haze pollution on water-soluble chemical species in PM 2.5 and size-resolved particles at an urban site during fall

Abstract Ground-based measurements were conducted from August 25 to September 8 of 2011 for understandingcharacteristics of carbonaceous aerosols measured at Gosan. Chemical components and their sources werediscussed by analysis of organic compounds with identification of primary and secondary products in particulatematter. 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 toimprove the carbon fractionation of the analytical method. In addition, organic compounds by gas chromatographytechnique 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 aromaticacids and PAHs. We concluded that the aging process was influenced by the long-range transport from East Seaarea. Key words : Organic, Organic compounds, OC, EC

Qualitative assessment to determine internal and external factors influencing the origin of styrene oligomers pollution by polystyrene plastic in coastal marine environments

To investigate the influence of haze on the chemical composition and formation processes of ambient aerosol particles, PM2.5 and size-segregated aerosol particles were collected daily during fall at an urban site of Gwangju, Korea. During the study period, the total concentration of secondary ionic species (SIS) contributed an average of 43.9% to the PM2.5, whereas the contribution of SIS to the PM2.5 during the haze period was 62.3%. The NO3- and SO42- concentrations in PM2.5 during the haze period were highly elevated, being 13.4 and 5.0 times higher than those during non-haze period, respectively. The PM, NO3-, SO42-, oxalate, water-soluble organic carbon (WSOC), and humic-like substances (HULIS) had tri-modal size distributions peaks at 0.32, 1.0, and 5.2μm during the non-haze and haze periods. However, during the non-haze period they exhibited dominant size distributions at the condensation mode peaking at 0.32μm, while on October 21 when the heaviest haze event occurred, they had predominant droplet mode size distributions peaking at 1.00μm. Moreover, strong correlations of WSOC and HULIS with SO42-, oxalate, and K+ at particle sizes of <1.8μm indicate that secondary processes and emissions from biomass burning could be responsible for WSOC and HULIS formations. It was found that the factors affecting haze formation could be the local stable synoptic conditions, including the weak surface winds and high surface pressures, the long-range transportation of haze from eastern China and upwind regions of the Korean peninsula, as well as the locally emitted and produced aerosol particles.

Source contributions and potential source regions of size-resolved water-soluble organic carbon measured at an urban site over one year

The objective of this study is to investigate the qualitative contribution of internal and external factors of the area contaminated by polystyrene (PS) in coastal marine environments. This study is based on the extensive results of monitoring the styrene oligomers (SOs) present in sand and seawater samples along various coastlines of the Pacific Ocean. Here, anthropogenic SOs is derived from PS during manufacture and use, and can provide clues about the origin of SOs by PS pollution. The monitoring results showed that, if the concentration of SOs in water is higher than those concentrations in beach sand, this area could be affected by PS plastic caused by an external factor. On the other hand, if the concentration of SOs is higher in the beach sand, the region can be mainly influenced by PS plastic derived from its own area. Unlike the case of an external factor, in this case (internal influence), it is possible to take policy measures of the area itself for the PS plastic problem. Thus, this study is motivated by the need of policy measures to establish a specific alternative to the problems of PS plastic pollution in ocean environments.

Intercomparison of Number Concentrations by CPCs using Generated Particles in Chamber

In this study, 24 h size-segregated particulate matter (PM) samples were collected between September 2012 and August 2013 at an urban site in Korea to investigate seasonal mass size distributions of PM and its water-soluble components as well as to infer the possible sources of size-resolved water-soluble organic carbon (WSOC) using a positive matrix factorization (PMF) model. The potential source contribution function (PSCF) was also computed to identify the possible source regions of size-resolved WSOC. The seasonal average contribution of water-soluble organic matter to PM1.8 was in the range from 12.7 to 19.7%, but higher (21.0%) and lower contributions (8.9%) were observed during a severe haze event and an Asian dust event, respectively. The seasonal mass size distribution of WSOC had a dominant droplet mode peaking at 0.55 μm and a minor coarse mode peaking at 3.1 μm. The droplet mode WSOC was found to strongly correlate with oxalate, SO42-, NO3-, and K+, suggesting that in-cloud processes and biomass burning emissions are important sources of droplet mode WSOC. This finding was verified by the results obtained using PMF models. Secondary organic aerosols (oxalate + SO42- + NO3-) and biomass burning were the most important contributors (70.3%) to condensation mode WSOC. In the droplet mode, in-cloud processes and secondary NO3- (+biomass burning) were important sources of WSOC, contributing on average 46.4 and 25.9% to the WSOC, respectively. In the coarse mode, soil dust and secondary processes contributed 52.5 and 42.5% to the WSOC, respectively. The PMF analyses and PSCF maps of WSOC, SO42-, and K+ indicate that condensation mode WSOC was mostly influenced by the secondary organic aerosols and biomass burning from both local and long-range transported pollutants, while droplet mode WSOC was primarily the result of atmospheric processing during the long range transport of biogenic and anthropogenic pollutants from the eastern regions of China.

Emission Characteristics of Elemental Constituents in Fine Particulate Matter Using a Semi-continuous Measurement System

Abstract Two butanol-based Condensation Particle Counters(CPC 3022, CPC 3025), three water-based CPCs(CPC3781,CPC3785×2), a Gardner Counter, a Fast Mobility Particle Sizer (FMPS), and an Aerosol Electrometer (AE) weredeployed to measure the number concentrations from atomized aerosol under six different conditions. Comparisonsof particle number concentrations measured by the CPCs, FMPS, and AE were conducted to evaluate the perfor-mance of the each CPCs using laboratory generated artificial particles such as NaCl, succinic acid (C 4 H 6 O 4 ), andparticles generated by propane torch & heat gun in the chamber. Good correlation between the CPC3025 and FMPSwas observed for the total particle number concentrations in the size range 15 nm to 90 nm. In addition, this papersuggests that photometric mode in water-based CPC3785 could not be used as quantitative of number concentra-tions for CPC3785. Key words : CPC, FMPS, Aerosol Electrometer, Size distribution, Comparison *Corresponding author.Tel : +82-(0)61-450-2485, E-mail : minsbae@hotmail.com