• Journal of the Korean earth science society
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• v.31 no.6
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• pp.600-607
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• 2010

In 2008, multiple episodes of large-scale transport of natural airborne particles and anthropogenically affected particles from different sources in the East Asian continent were identified in the National Oceanic and Atmospheric Administration (NOAA) satellite RGB-composite images and the mass concentrations of ground level particulate matters. To analyze the aerosol size distribution during the large-scale transport of atmospheric aerosols, both aerosol optical depth (AOD; proportional to the aerosol total loading in the vertical column) and fine aerosol weighting (FW; fractional contribution of fine aerosol to the total AOD) of Moderate resolution Imaging Spectroradiometer (MODIS) aerosol products were used over the East Asian region. The six episodes of massive natural airborne particles were observed at Cheongwon, originating from sandstorms in northern China, Mongolia and the loess plateau of China. The $PM_{10}$ and $PM_{2.5}$ stood at 70% and 16% of the total mass concentration of TSP, respectively. However, the mass concentration of $PM_{2.5}$ among TSP increased as high as 23% in the episode in which they were flowing in by way f the industrial area in east China. In the other five episodes of anthropogenically affected particles that flowed into the Korean Peninsula from east China, the mass concentrations of $PM_{10}$ and $PM_{2.5}$ among TSP reached 82% and 65%, respectively. The average AOD for the large-scale transport of anthropogenically affected particle episodes in the East Asian region was measured at $0.42{\pm}0.17$ compared with AOD ($0.36{\pm}0.13$) for the natural airborne particle episodes. Particularly, the regions covering east China, the Yellow Sea, the Korean Peninsula, and the east Korean sea were characterized by high levels of AOD. The average FW values observed during the event of anthropogenically affected aerosols ($0.63{\pm}0.16$) were moderately higher than those of natural airborne particles ($0.52{\pm}0.13$). This observation suggests that anthropogenically affected particles contribute greatly to the atmospheric aerosols in East Asia.

• Analytical Science and Technology
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• v.14 no.5
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• pp.442-450
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• 2001

In this study, we collected PM10(particulate matter less than $10{\mu}m$) by using a high volume air sampler from March 2000 to September 2000 to investigate the contamination level and the distribution characteristics of heavy metals in the ambient air in Ulsan area. Samples were pretreated by the microwave extraction methods, and heaby metals (Cr, Cu, Zn, Cd, Ni, As, and Pb) were quantified by using and ICP-MS system. The highest PM10 concentrations in the ambient air were $85.6{\mu}g/m^3$ and the aberage value was $37.1{\mu}g/m^3$. The maximum levels of each heavy metal were as follows: $2.5{\mu}g/m^3$ for Fe(Yeocheon-dong), $0.41{\mu}g/m^3$ for Zn(Nammok-2-dong), $0.061{\mu}g/m^3$ for Cd(Yeocheon-dong), $0.20{\mu}g/m^3$ for Pb(Yeocheon-dong), $0.037{\mu}g/m^3$ for Ni(Yeoncheon-dong), $0.88{\mu}g/m^3$ for Cu(Yaeum-dong), $0.042{\mu}g/m^3$ for Cr(Yaeum-dong), and $0.015{\mu}g/m^3$ for As(Onsan). Among concentration of heavy metals, Ni and Zn compounds were highly correlated with a correlation coefficient of 0.87 at Nammok-2-dong.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.1
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• pp.20-28
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• 2014

The three air quality monitoring sites, analysed simultaneously PM-10 and PM-2.5, ie. Ihyeondong in industrial area, Manchondong in residential area, Pyeongnidong in streetside, among 13 air quality monitoring sites in Daegu area, were investigated the concentration distribution characteristics of PM-2.5 and PM-10 in the last 2 years (2011~2012). PM-10 concentrations exceeded annual average reference value ($50{\mu}g/m^3$) in Ihyeondong ($52.5{\mu}g/m^3$) and Pyeongnidong ($60.9{\mu}g/m^3$) but satisfied in Manchondong ($44.9{\mu}g/m^3$). All PM-2.5 concentrations exceeded EPA annual standard value of the United States ($15{\mu}g/m^3$) in three points, but also exceeded new control annual standard value ($25{\mu}g/m^3$) coming into effect in 2015. Seasonal concentration of PM-10 appeared the order of spring > winter > fall > summer, and in the case of PM-2.5, the order was winter > spring > fall > summer. Monthly concentrations of PM-10 and PM-2.5 were highest in February and lowest in September. Diurnal concentrations of PM-10 and PM-2.5 increased from 7:00 AM, and recorded the highest concentration between 10:00 AM and 11:00 AM. And after 6:00 PM it lowered continuously and tended to show fixed concentrations from evening until early morning. In addition, the concentration of fine particles during the week was higher than the weekend. The fluctuation in industrial area was larger than the residential area. At the PM-2.5/PM-10 ratio, summer was generally high, spring was the lowest. And, when yellow sand occurred, it was 0.32 to 0.42. It was very low compared to 0.54 to 0.64 during non-yellow sand times. This paper for the state and the characteristics of Daegu' fine particles (PM-10, PM-2.5) will be valuable to future researches of fine particles and air pollution management.

• Korean Journal of Microbiology
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• v.48 no.2
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• pp.134-140
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• 2012

Asian dust storms originating in the arid desert of China and Mongolia usually occur from late winter through spring, and more than one million tons of dust per year is transported to the Korean Peninsula by the prevalent westerly winds. We supposed that these dust particles could include bioaerosols and act as carriers of microorganisms. In order to clarify the dynamics of microorganisms moving with these particles, the concentration and composition of microorganisms associated with settled particles were compared between samples collected during Asian dust events and those under non-dust periods. From February to April 2008, settled dust particles were collected at one location in Ulsan using rainfall meter of 200 mm diameter. During this period, there was one Asian dust event in Ulsan. The bacterial concentrations were higher in samples collected during Asian dust event than those under non-dust period, whereas fungal concentrations were rather similar regardless of the Asian dust event. We analyzed 16S rRNA gene sequences of 45 bacterial isolates obtained from the settled particle samples. These isolates belonged to either genus Bacillus or genus Streptococcus and were tentatively identified as B. amyloliquefaciens, B. aryabhattai, B. atrophaeus, B. licheniformis, B. megaterium, B. methylotrophicus, B. pumilus, B. sonorensis, B. subtlis, B. vallismortis, S. epidermidis, and S. succinus. In cases of fungal isolates, genera such as Mucor, Alternaria, Cladosporium, and Aspergillus were tentatively identified from samples collected at both Asian dust and non-Asian dust periods. It appears that endospore-forming bacteria such as Bacillus sp. rather than fungal spores are more likely to be associated with Asian dust particles.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.59-64
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• 2012

Polystyrene latex spheres (PLS) were prepared as artificial dusts by the emulsion polymerization with potassium persulfate (KPS) and sodium dodecyl sulfonate (SDS) as an initiator and a stabilizer, respectively. The reaction temperature and the concentration of the initiator and stabilizer were chosen as variables to control the PLS particle size. As temperature increased, the particle size decreased considerably. Furthermore, the PLS particle size and their size distributions can be controlled minutely by adjusting the concentrations of KPS and SDS. It is confirmed that the PLS prepared in this work is monodispersed with the coefficient of variance less than 7% and are in the range of 0.1~0.5 ${\mu}m$, which are good for using as artificial dusts.

• Journal of the Korean Data and Information Science Society
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• v.27 no.4
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• pp.1001-1012
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• 2016

It is well known that air pollutants exert a bad influence on human health. According to the United Nations Environment Program, 4.3 million people die from carbon monoxide and particulate matter annually from all over the world. Carbon monoxide is a toxic gas that is the most dangerous of the gas consisting of carbon and oxygen. In this paper, we used 1 hour, 6 hours, 12 hours, and 24 hours average carbon monoxide concentration data collected between 2004 and 2013 in Daegu Gyeongbuk area. Parameters of the generalized extreme value distribution were estimated by maximum likelihood estimation and L-moments estimation. An evalution of goodness of fitness also was performed. Since the number of samples were small, L-moment estimation turned out to be suitable for parameter estimation. We also calculated 5 year, 10 year, 20 year, and 40 year return level.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.3
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• pp.75-80
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• 2019

The article is devoted to the interpretation of ammonia, one of the fine dust precursors, absorption behavior in water turbulent flow. The water flow was considered as a turbulent flow with Reynolds number more than $10^4$, because ammonia gas penetration depth was deeper at turbulent flow compared to laminar flow. For the interpretation, the dimensionless mass transfer governing-equation and the constant physical-properties at room temperature were used. The diffusivity of ammonia in water and the kinematic viscosity of water were $2{\times}10^{-9}m^2/s$ and $1{\times}10^{-6}m^2/s$, respectively. The concentration distribution of ammonia in water was estimated with respect to the position from the point where the water started to be exposed to ammonia. The quantitative distribution as a function of the mixing length was also acquired. The quantitative interpretation may provide the insight how much the turbulent flow was more efficient to remove ammonia rather than the laminar flow.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.90-108
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• 2015

The WRF-Chem model was applied to simulate the Asian dust event affecting the Korean Peninsula from 11 to 13 November 2010. GOCART dust emission schemes, RADM2 chemical mechanism, and MADE/SORGAM aerosol scheme were adopted within the WRF-Chem model to predict dust aerosol concentrations. The results in the model simulations were identified by comparing with the weather maps, satellite images, monitoring data of $PM_{10}$ concentration, and LIDAR images. The model results showed a good agreement with the long-range transport from the dust source area such as Northeastern China and Mongolia to the Korean Peninsula. Comparison of the time series of $PM_{10}$ concentration measured at Backnungdo showed that the correlation coefficient was 0.736, and the root mean square error was $192.73{\mu}g/m^3$. The spatial distribution of $PM_{10}$ concentration using the WRF-Chem model was similar to that of the $PM_{2.5}$ which were about a half of $PM_{10}$. Also, they were much alike in those of the UM-ADAM model simulated by the Korean Meteorological Administration. Meanwhile, the spatial distributions of $PM_{10}$ concentrations during the Asian dust events had relevance to those of both the wind speed of u component ($ms^{-1}$) and the PBL height (m). We performed a regressive analysis between $PM_{10}$ concentrations and two meteorological variables (u component and PBL) in the strong dust event in autumn (CASE 1, on 11 to 23 March 2010) and the weak dust event in spring (CASE 2, on 19 to 20 March 2011), respectively.

• Journal of Environmental Science International
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• v.26 no.1
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• pp.55-65
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• 2017

Average concentration of PM in Seoul metropolitan area satisfied the Korean air quality standard in 2010. Furthermore, concentration of PM in all boroughs across Seoul met the air environment standard in 2012. $PM_{10}$ concentration was relatively higher in center of Seoul in comparison to the rest, while $PM_{2.5}$ concentration showed exactly the contrary result. We analyzed the effect that PM emissions from vehicles would have on PM concentrations across Seoul. The results showed that average annual PM concentration recently decreased in Seoul although the number of vehicles registered annually continued its upward trend. By contrast, average fine dust concentrations in Seoul showed a decline which suggested that correlation between annual average PM concentrations and number of registered vehicles remained low. However, year-on-year vehicle registration rate recently showed a declining tendency in the same way as the trend of changes in average PM concentrations. Particularly, the upward trend in annual average PM concentrations in 2002 and 2007 was consistent with the increase in vehicle registration rate, suggesting that vehicle registration rate was closely associated with changes in PM concentrations.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.179-179
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• 2022

최근 화두가 되고 있는 환경문제 중 하나로 녹조현상을 꼽을 수 있다. 녹조란 남세균이 대량 증식함으로써 물빛이 녹색으로 변하는 현상으로, 영양염류 및 수온 등 이화학적 요소뿐만 아니라체류시간과 같은 수리학적 요인까지 모두 충족되었을 때 발생한다. 심하면 고밀도의 스컴(scum)을 형성하며 독소와 악취를 동반하기도 한다. 유해 남세균이 생성하는 마이크로시스틴(microcystin, MC)이 함유된 물을 입 또는 코로 섭취시 간을 손상시킨다는 보고가 있으며, 최근 해외에서는 MC가 미세먼지처럼 공기 중에 떠다니다 수변에서 생활하는 사람의 호흡기로 들어가 건강 피해를 줄 수 있다는 연구가 속속 나오고 있다. 본 연구는 우리나라 최초의 수질개선용 댐인 영주댐을 연구 대상으로 삼아 수질 모델링을 구축하고 영주댐 운영에 따른 댐 상·하류 조류 변화를 정량적으로 분석하였다. 조류의 강도를 추정하는데 클로로필-a 농도를 사용하였으며, 분석 도구로는 국립환경과학원이 수질예측 및 평가 시 사용하는 EFDC(Environmental Fluid Dynamics Code) 모형을 활용하였다. 대상 구간의 실제 폭, 하상고 분포 등을 고려하여 수표면 격자망을 구현하였으며, 환경부에서 제공하는 수위 및 DO, TN, T-P, 클로로필-a 등을 활용하여 EFDC 모형의 수리 및 수질 재현성 검토를 하였다. 검·보정된 EFDC 모형으로 영주댐의 방류량 변화 및 댐의 개방과 같은 수리학적 요인을 제어하여 특정 지점의 조류 변화를 분석하였다.