• Journal of Korean Society for Atmospheric Environment
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• v.34 no.1
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• pp.16-37
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• 2018

In this study, difference in chemical composition of $PM_{2.5}$ observed between the year 2013 and 2015 at six air quality intensive monitoring stations (Bangryenogdo (BR), Seoul (SL), Daejeon (DJ), Gwangju (GJ), Ulsan (US), and Jeju (JJ)) was investigated and the possible factors causing their difference were also discussed. $PM_{2.5}$, organic and elemental carbon (OC and EC), and water-soluble ionic species concentrations were observed on a hourly basis in the six stations. The difference in chemical composition by regions was examined based on emissions of gaseous criteria pollutants (CO, $SO_2$, and $NO_2$), meteorological parameters (wind speed, temperature, and relative humidity), and origins and transport pathways of air masses. For the years 2013 and 2014, annual average $PM_{2.5}$ was in the order of SL ($${\sim_=}DJ$$)>GJ>BR>US>JJ, but the highest concentration in 2015 was found at DJ, following by GJ ($${\sim_=}SJ$$)>BR>US>JJ. Similar patterns were found in $SO{_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$. Lower $PM_{2.5}$ at SL than at DJ and GJ was resulted from low concentrations of secondary ionic species. Annual average concentrations of OC and EC by regions had no big difference among the years, but their patterns were distinct from the $PM_{2.5}$, $SO{_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$ concentrations by regions. 4-day air mass backward trajectory calculations indicated that in the event of daily average $PM_{2.5}$ exceeding the monthly average values, >70% of the air masses reaching the all stations were coming from northeastern Chinese polluted regions, indicating the long-range transportation (LTP) was an important contributor to $PM_{2.5}$ and its chemical composition at the stations. Lower concentrations of secondary ionic species and $PM_{2.5}$ at SL in 2015 than those at DJ and GJ sites were due to the decrease in impact by LTP from polluted Chinese regions, rather than the difference in local emissions of criteria gas pollutants ($SO_2$, $NO_2$, and $NH_3$) among the SL, DJ, and GJ sites. The difference in annual average $SO{_4}^{2-}$ by regions was resulted from combination of the difference in local $SO_2$ emissions and chemical conversion of $SO_2$ to $SO{_4}^{2-}$, and LTP from China. However, the $SO{_4}^{2-}$ at the sites were more influenced by LTP than the formation by chemical transformation of locally emitted $SO_2$. The $NO_3{^-}$ increase was closely associated with the increase in local emissions of nitrogen oxides at four urban sites except for the BR and JJ, as well as the LTP with a small contribution. Among the meterological parameters (wind speed, temperature, and relative humidity), the ambient temperature was most important factor to control the variation of $PM_{2.5}$ and its major chemical components concentrations. In other words, as the average temperature increases, the $PM_{2.5}$, OC, EC, and $NO_3{^-}$ concentrations showed a decreasing tendency, especially with a prominent feature in $NO_3{^-}$. Results from a case study that examined the $PM_{2.5}$ and its major chemical data observed between February 19 and March 2, 2014 at the all stations suggest that ambient $SO{_4}^{2-}$ and $NO_3{^-}$ concentrations are not necessarily proportional to the concentrations of their precursor emissions because the rates at which they form and their gas/particle partitioning may be controlled by factors (e.g., long range transportation) other than the concentration of the precursor gases.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2461-2476
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• 2013

To assess environmental contamination with carcinogens, carbonaceous compounds, water-soluble ionic species and trace gaseous species were identified and quantified every three hours for three days st three different atmospheric layer at the heart of chiang-Mai, bangkok and hat-Yai from December 2006 to February 2007. A DRI model 2001 Themal/Optical Carbon Analyzer with the IMPROVE thermal/optical reflectance (TOR) protocol was used to quantify the organic carbon(OC) and elemental carbon content in $PM_{10}$. Diurnal and vertical variability was also carefully investigated. In general, OC and EC contenttration shoeed the highest values at the monitoring period o 21.00-00.00 as consequences of human activities at night bazaar coupled with reduction of mixing layer, decreased wind speed and termination of photolysis nighttime. Morning peaks of carboaceous compounds were observed during the sampling period of 06:00 -09:00, emphasizing the main contribution of traffic emission in the three cities. The estimation of incremental lifetime partculate matter exposure (ILPE) raises concern of high risk of carbonaceous accumulation over workers and residents living close to the observatory sites. The average values of incremental lifrtime particulate matter exposure (ILPE) of total carbon at Baiyoke Suit Hotel and Baiyoke Sky Hotel are approsimately ten time shigher then those air sample collected at prince of songkla University Hat-Yai campus corpse incinerator and fish-can maufacturing factory but only slightly higher than those of rice straw burnig in Songkla province. This indicates a high risk of developing lung cancer and other respiratory diseases across workers and residents living in high buildings located in Pratunam area. Using knowledge of carbonaceous fractions in $PM_{10}$, one can estimate the gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs). Dachs-Eisenreich model highlights the crucial role of adsorption in gas-particle partitioning of low molecular weight PAHs, whereas both absorption and adsorption tend to account for gas-particle partitioning of high molecular weight PAHs in urban residential zones of Thailand. Interestingly, the absorption mode alone plays a minor role in gas-partcle partitiining of PAHs in Chiang-Mai, Bangkok and hat-Yai.

• Particle and aerosol research
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• v.7 no.2
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• pp.49-57
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• 2011

High concentration of PM10 was reported on late July, 2005 in Seoul along with high particulate ion concentrations in PM2.5. To identify the reason for the severe air pollution episode, time series analysis of the PM10 concentration in the monitoring sites over Korea, wind sector analysis, trend analysis of the ion concentrations, and air mass trajectory analysis were carried out. It was found that the episode could be classified into two separate periods; first one between July 22 and 27 and second one between July 28 and 31. During the first period, the PM10 concentrations at Seoul were in good correlation with the PM10 concentration three hours before at Chuncheon. Trajectory analysis showed that air mass moved from north and turned to west at Kangwon province to Seoul. The concentrations of PM10 mass and ionic species were lower than the second period. During the second period, air mass moved from northern China to Seoul directly and the PM10 concentrations all over the mid-Korean peninsula showed the same trend. These observations suggest that the air pollution during the second period was affected by direct transport of air pollutants from northern China. Thus, the air quality at Seoul during both periods were influenced by long-range transport from outside rather than by local sources, but with different transport patterns.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.321-330
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• 2011

We experimentally investigated the effect of applied DC electric fields on the flame spread over polyethylene-coated electrical wire. The flame-spread rates over electrical wire with negative and positive DC electric fields from 0 to ${\pm}7$ kV were measured and analyzed. We compared the results for DC electric fields with previous results for AC electric fields. We explored whether or not various flame shapes could be obtained with DC electric fields and the main reason for the flame-spread acceleration, particularly at the end of the electrical wire, for AC electric fields. We found that DC electric fields do not significantly affect the flame-spread rates. However, the flame shape is mildly altered by the ionic wind effect even for DC electric fields. The flame-spread rate is relevant to the flame shape and the slanted direction in spite of the mild impact. A possible explanation for the flame spread is given by a thermal-balance mechanism and fuel-vapor jet.