• 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.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.669-678
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• 2021

This study surveyed three land cover types in Chungju City in Chungcheongbuk Province to check the distribution of cultured bacteria in bio-aerosols according to land cover type. It was possible to compare and analyze the distribution of bacteria according to microclimatic changes at each measurement point by examining meteorological factors and bio-aerosols according to land cover. The microclimate temperature in each measurement point was 8.7℃ for the urban forest, 10.8℃ for the waterside green area, and 10.2℃ for the urban area, indicating the urban forest had the lowest temperature among the measurement points. The relative humanity was 61.8% fin the urban forest, 59.3% in the waterside green area, and 55.7% in the urban area, indicating that the urban forest was the most humid among the measurement points. The identified bacteria were found to be 43 genera and 99 species. In terms of species diversity of cultured bacteria, 22 genera were found in the waterside green area, 21 genera in the urban forest, and 17 genera in the urban area, 37 species were found in the waterside green area, 31 species in the urban area, and 31 species in the urban forest. Bacillus toyonensis and Pseudarthrobacter oxydan were the species present in all three types of measurement sites, and Herbiconiux flava was confirmed to inhabit green areas such as urban forests and waterside green areas. The analysis result of the bacterial concentration according to the microclimatic environment in each measurement point was 333 CFU/m³ in the urban forest, 287 CFU/m³, in the waterside green area, and 173 CFU/m³ in the downtown area. The relative humidity and wind speed were analyzed to show a similar trend as the concentration. This study is expected to provide basic data for healthy urban management and green area creation by identifying the distribution of cultured bacteria in bio-aerosols according to land cover type and comparing and analyzing the traits of bio-aerosol in each measurement point.

• Korean Journal of Remote Sensing
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• v.32 no.6
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• pp.629-637
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• 2016

In this present study, we identified the $SO_2$ effect on $O_3$ retrieval from the Ozone Monitoring Instrument (OMI) measurement over Chinese Industrial region from 2005 through 2007. The Planetary boundary layer (PBL) $SO_2$ data measured by OMI sensor is used in this present study. OMI-Total Ozone Mapping Spectrometer (TOMS) total $O_3$ is compared with OMI-Differential Optical Absorption Spectrometer (DOAS) total $O_3$ in various $SO_2$ condition in PBL. The difference between OMI-TOMS and OMI-DOAS total $O_3$ (T-D) shows dependency on $SO_2$ (R (Correlation coefficient) = 0.36). Since aerosol has been reported to cause uncertainty of both OMI-TOMS and OMI-DOAS total $O_3$ retrieval, the aerosol effect on relationship between PBL $SO_2$ and T-D is investigated with changing Aerosol Optical Depth (AOD). There is negligible aerosol effect on the relationship showing similar slope ($1.83{\leq}slope{\leq}2.36$) between PBL $SO_2$ and T-D in various AOD conditions. We also found that the rate of change in T-D per 1.0 DU change in PBL, middle troposphere (TRM), and upper troposphere and stratosphere (STL) are 1.6 DU, 3.9 DU and 4.9 DU, respectively. It shows that the altitude where $SO_2$ exist can affect the value of T-D, which could be due to reduced absolute radiance sensitivity in the boundary layer at 317.5 nm which is used to retrieve OMI-TOMS ozone in boundary layer.

• Journal of Soil and Groundwater Environment
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• v.25 no.3
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• pp.74-83
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• 2020

Since fine dust (PM₁₀) has a significant influence on soil and groundwater composition during dry and wet deposition processes, it is of a vital importance to understand the fate and transport of aerosol in geological environments. Fine dust is formed after the chemical reaction of several precursors, typically observed in short intervals within a few hours. In this study, deep learning approach was applied to predict the fate of fine dust in an urban area. Deep learning training was performed by combining convolutional neural network (CNN) and recurrent neural network (RNN) techniques. The PM₁₀ concentration after 1 hour was predicted based on three-hour data by setting SO₂, CO, O₃, NO₂, and PM₁₀ as training data. The obtained coefficient of determination value, R², was 0.8973 between predicted and measured values for the entire concentration range of PM₁₀, suggesting deep learning method can be developed into a reliable and viable tool for prediction of fine dust concentration.

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.105-112
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• 2011

In order to investigate the effects of local and synoptic meteorological conditions on urban scale particulate air pollutants observed over the Busan coastal area, power spectrum analysis was applied to observed particulate matter with an aerodynamic diameter $\leq10\;{\mu}m$ ($PM_{10}$) for the period from 1 October, 1993 to 31 December, 2004. Fast Fourier Transform (FFT) analysis was used to obtain the hourly mean observed $PM_{10}$ concentrations to identify different periodicity scales of $PM_{10}$ concentrations. The results showed that, aside from the typical and well-known periodicities such as diurnal and annual variations caused by anthropogenic influences, three other significant power spectral density peaks were identified: 7-day, 21-day and 2.25-year periodicities. Cospectrum analysis indicated that the seven-day variations were closely related to the synoptic meteorological conditions such as weak wind speed, which are relevant to the stagnant high pressure system slowly passing through the Korean Peninsula. The intra-seasonal 21-day variation was negatively correlated with wind speed but was consistently positively correlated with relative humidity, which is related to aerosol formation that can be achieved as a result of the hygroscopic characteristics of aerosols. However, the quasibiennial 2.25-year variation was correlated with the frequency of Asian dust occurrence, the periodicities of which have been recorded inter-annually over the Korean Peninsula.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.1-10
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• 1998

Relationships between TSP and PM10 concentrations were evaluated using their respective data sets collected from Taegu and Kyeungsan areas during the period of December 1993 to November 1994. The collection of data was made using the gravimetric and $\beta$-ray absorption ($\beta$-MPM) methods for 7 days of every month from three urban sites in Taegu and one suburban site in Kyeungsan. Correlation coefficients between TSP and PM10 concentrations for these four sampling sites were found in the range of 0.85 $\sim$ 0.96. Correlation analysis was also conducted for $\beta$-PM concentration data that were measured only from the residential and commercial sites. The correlation coefficients between TSP and $\beta$-PM concentrations were 0.9 in the residential site and 0.8 in the commercial site. By contrast, the correlation coefficients between PM10 $\beta$-PM concentrations were almost identical for both the residential and commercial sites with a value of 0.88. The mean ratio for PM10 to TSP concentrations for all sites was appeared to be 0.68. The analysis of seasonal trends in PM10/TSP ratios showed that the contribution of PM10 to TSP concentrations was more significant during winter (0.70 $\sim$ 0.75) than during summer (0.61 $\sim$ 0.68). The results of this study may provide empirical informations on the compatability of aerosol data measured by different sampling methods.

• Asian Journal of Atmospheric Environment
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• v.7 no.3
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• pp.152-160
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• 2013

Seven potentially harmful bifunctional carbonyls were measured in particulate and gaseous phases at a roadside site and a suburban site in an area about 30 km north-northwest from Tokyo metropolitan area in the Kanto region in Japan. For the first time, these compounds were measured in both phases with a time resolution of 2 h. We found that wind direction is an important parameter that affects the collection of these compounds near the source, and it can cover the effects of other important variables. Our results confirmed that motor vehicles and especially diesel fuelled vehicles are important sources of these compounds. Photochemical generation is also an important source of these compounds in the gaseous phase. Transportation from the urban area is also important, particularly in the aerosol phase.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.4
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• pp.323-332
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• 2013

Objectives: This study was conducted in order to investigate the diesel exhaust particle(DEP) concentrations in the thirteen parking lots of large shopping complex. Methods: The real-time black carbon(BC) concentration was determined using an Aethalometer, and elemental/organic carbon concentration was determined according to the method of the National Institute for Occupational Safety and Health(NIOSH) 5040. The particle number concentration(NC), lung deposited surface area concentration(LDSA) and geometric mean diameter(GMD) were determined using a DiSCmini aerosol monitor. Results: The average concentration of BC, EC, OC, NC, LDSA and GMD were $19.1{\mu}g/m^3$, $12.6{\mu}g/m^3$, $51.5{\mu}g/m^3$, $94,000particles/cm^{-3}$, $298{\mu}m^2/cm^{-3}$ and 57 nm in all parking lots, respectively, approximately 3-fold higher than those found in the urban outdoor. The average concentration of BC were $21.3{\mu}g/m^3$ in underground parking lots, 3-fold higher than above parking lots. Conclusions: Therefore, the parking lots at the large shopping complex can be considered a potentially dangerous environment with a high concentration of DEP nanoparticles.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3427-3432
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• 2014

This study introduces a new method of combining Imaging Differential Optical Absorption Spectroscopy (Imaging-DOAS) data and plume dispersion formulas for power plant emissions to determine the three-dimensional structure of a dispersing pollution plume and the spatial distributions of trace gas volume mixing ratios (VMRs) under conditions of negligible water droplet and aerosol effects on radiative transfer within the plume. This novel remote-sensing method, applied to a power plant stack plume, was used to calculate the two-dimensional distributions of sulfur dioxide ($SO_2$) and nitrogen dioxide ($NO_2$) VMRs in stack emissions for the first time. High $SO_2$ VMRs were observed only near the emission source, whereas high $NO_2$ VMRs were observed at locations several hundreds of meters away from the initial emission. The results of this study demonstrate the capability of this new method as a tool for estimating plume dimensions and trace gas VMRs in power plant emissions.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.3
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• pp.279-290
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• 1995

Recently in Korea, due to the significant drop of lead and bromine levels as a marker of autoemission source in the urban areas, the conventional application of receptor methods has many difficulties to properly apportion mass contribution of some sources. It is then needed to urgently develop alternative source profiles and identify new emission markers. Thus, the study has extensively examined the results obtained from using PAHs and elemental data for receptor modeling and has provided an opportunity to identify alternative source compositions and to determine a proper number of the ambient emission sources in Seoul area. The purpose of the study is to identify the sources of PM-10 and to estimate their mass contributions in Seoul area. Thus, a receptor model, target transformation factor analysis(TTFA) has been massively applied. The TTFA offers the possibility of determining the number of sources and their mass contributions. The input data used in this study are composed of two separate sets: fine (d$_{p}$ < 2.5.mu.m) and coarse (2.5.mu.m < d$_{p}$ < 10.mu.m) mode aerosol samples. Each sample was simultaneously collected by a PM-10 dichotomous sampler during the daytime(8 AM to 8 PM) and the nighttime(8 PM to 8 AM) from February to October 1993 on the Sungdong-Gu, Seoul. All the samples were analyzed to determine the levels of 10 inorganic elements by an XRF system as well as 14 PAHs by a HPLC. However, only 8 inorganic elements and 7 PAHs were used for the various statistical analysis.sis.