• Title/Summary/Keyword: Aerosols

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MODIS-estimated Microphysical Properties of Clouds Developed in the Presence of Biomass Burning Aerosols (MODIS 관측자료를 이용한 러시아 산불 영향 하에 발달한 구름의 미세 물리적 특성 연구)

  • Kim, Shin-Young;Sohn, Byung-Ju
    • Korean Journal of Remote Sensing
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    • v.24 no.4
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    • pp.289-298
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    • 2008
  • An algorithm was developed to retrieve both cloud optical thickness and effective particle radius considered the aerosol effect on clouds. This study apply the algorithm of Nakajima and Nakajima (1995) that is used to retrieve cloud optical thickness and effective particle radius from visible, near infrared satellite spectral measurements. To retrieve cloud properties, Look-up table (LUT) was made under different atmospheric conditions by using a radiative transfer model. Especially the vertical distribution of aerosol is based on a tropospheric aerosol profile in radiative transfer model. In the case study, we selected the extensive forest fire occurred in Russia in May 2003. The aerosol released from this fire may be transported to Korea. Cloud properties obtained from these distinct atmospheric situations are analysed in terms of their possible changes due to the interactions of the clouds with the aerosol particle plumes. Cloud properties over the East sea at this time was retrieved using new algorithm. The algorithm is applied to measurements from the MODerate Resolution Imaging Spectrometer (MODIS) onboard the Terra spacecrafts. As a result, cloud effective particle radius was decreased and cloud optical thickness was increased during aerosol event. Specially, cloud effective particle radius is hardly greater than $20{\mu}m$ when aerosol particles were present over the East Sea. Clouds developing in the aerosol event tend to have more numerous but smaller droplets.

The Present Status and Development Plan in the Field of Climate Change Science in Korea analyzed by the IPCC-IV Reports (IPCC-IV 국가 보고서 분석에 의한 한국의 기후변화과학 분야의 현황과 발전방향)

  • Chung, Yun-Ang;Chung, Hyo-Sang;Ryu, Chan-Su
    • Journal of Integrative Natural Science
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    • v.4 no.1
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    • pp.38-43
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    • 2011
  • The recent global warming may be estimated to give lots of impacts to the human society and biosphere of influencing climate change included by the natural climate variations through the human activity which can directly and/or indirectly play a major role of total atmospheric composition overall. Therefore it currently appears evidences such as hot wave, typhoon, and biosphere disturbance, etc. over the several regions to be influenced by global warming due to increasing the concentration of greenhouse gases in the atmosphere through inducing forest destruction, fossil fuel combustion, greenhouse gases emission, etc. since industrial revolution era. Through the working group report of IPCC (Intergovernmental Panel on Climate Change) for climate change was analyzed by the individual country's current status and figure out the important issues and problems related to the future trend of climate change science with advanced countries preparedness and research, In this study, the first working group report of IPCC focuses on those aspects of the current understanding of the physical science of climate change that are judged to be most relevant to policymakers. As this report was assessed and analyzed by including the progress of climate change science, the role of climate models and evolution in the treatment of uncertainties. This consists of the changes in atmospheric constituents(both aerosols and gases) that affect the radiative energy balance in the atmosphere and determine the Earth's climate, considering the interaction between biogeochemical cycles that affect atmospheric constituents and climate change, including aerosol/cloud interactions, the extensive range of observations snow available for the atmosphere and surface, for snow, ice, and frozen ground and for the oceans, respectively and changes in sea level, the paleoclimate perspective and assessment of evidence for past climate change and the extension, the ways in which physical processes are simulated in climate models and the evaluation of models against observed climate, the development plans and methods of improving expert and building manpower urgently and R&D fund expansion in detail for climate change science in Korea will be proposed.

Annual Distribution of Atmospheric Ammonia Concentration in Saemangum Reclaimed Land Area (새만금 간척지 지역 공기 중 암모니아 농도의 연간 분포)

  • Hong, Sung-Chang;Kim, Min-Wook;Kim, Jin-Ho
    • Korean Journal of Environmental Agriculture
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    • v.40 no.4
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    • pp.330-334
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    • 2021
  • BACKGROUND: More recently, it has been shown that atmospheric ammonia (NH3) plays a primary role in the formation of secondary particulate matter by reacting with the acidic species, e.g. SO2, NOx, to form PM2.5 aerosols in the atmosphere. The Jeonbuk region is an area with high concentration of particulate matter. Due to environmental changes in the Saemangeum reclaimed land with an area of 219 km2, it is necessary to evaluate the impact of the particulate matter and atmospheric ammonia in the Jeonbuk region. METHODS AND RESULTS: Atmospheric ammonia concentrations were measured from June 2020 to May 2021 using a passive sampler and CRDS analyzer. Seasonal and annual atmospheric ammonia concentration measured using passive sampler was significantly lower in Jangjado (background concentration), and the concentration ranged from 11.4 ㎍/m3 to 18.2 ㎍/m3. Atmospheric ammonia concentrations in Buan, Gimje, Gunsan, and Wanju regions did not show a significant difference, although there was a slight seasonal difference. The maximum atmospheric ammonia concentration measured using the CRDS analyzer installed in the IAMS near the Saemangeum reclaimed land was 51.5 ㎍/m3 in autumn, 48.0 ㎍/m3 in summer, 37.6 ㎍/m3 in winter, and 32.7 ㎍/m3 in spring. The minimum concentration was 4.9 ㎍/m3 in spring, 4.2 ㎍/m3 in summer, and 3.5 ㎍/m3 in autumn and winter. The annual average concentration was 14.6 ㎍/m3. CONCLUSION(S): Long term monitoring of atmospheric ammonia in agricultural areas is required to evaluate the formation of fine particulate matter and its impact on the environment. In addition, continuous technology development is needed to reduce ammonia emitted from farmland.

Characteristics of Carbonaceous and Organic Components in PM2.5 over the Yellow Sea (서해상 PM2.5 내 탄소성분 및 유기성분의 화학적 특성)

  • Yoo, Ha Young;Kim, Ki Ae;An, Hyunjin;Lee, Yeonjung;Zihui, Teng;Yoo, Hee-Jung;Kim, Jeong Eun;Ko, Hee-Jung;Sung, Min-Young;Choi, Jin-Soo;Park, Jin-Soo;Lee, Ji Yi
    • Atmosphere
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    • v.31 no.3
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    • pp.267-282
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    • 2021
  • Characteristics of carbonaceous components and organic compounds in PM2.5 over the atmosphere of the Yellow Sea were investigated. PM2.5 samples were collected onboard the meteorological research vessel, GISANG 1, over the Yellow Sea during the YES-AQ campaign in 2018 and 2019, respectively. The average concentrations of carbonaceous components in this region were 2.59 ± 1.59 ㎍ m-3 for the OC, 0.24 ± 0.10 ㎍ m-3 for the EC, 2.14 ± 1.30 ㎍ m-3 for the WSOC and 1.17 ± 0.94 ㎍ m-3 for the HULIS-C, respectively. The total concentration of 56 organic compounds (ΣOCs) accounts for 10% of OC. The main group among organic compounds were dicarboxylic acids which account for 57% of ΣOCs, followed by n-alkanoic acids accounting for 34% of ΣOCs. In n-alkanoic acid distribution, hexanoic (C6:0) and octanoic (C8:0) acids which are low molecular weight n-alkanoic acids and known as emitted from marine biogenic activities were dominant in this region. Furthermore, non-HULIS-C fraction increased when the air mass originated from the marine region rather than the continental region. When the Asian dust episode was observed, the WISOC concentrations along with the levoglucosan were increased, while the haze episodes caused the increase of WSOC, HULIC-S and DCAs. In this study, we found that the components of carbonaceous and organic aerosols in PM2.5 over the Yellow Sea were changed with the specific air pollution episodes. It indicates that the physicochemical properties of PM2.5 can be changed by the air pollution episodes in this region.

Derivation of Synergistic Aerosol Model by Using the ECMWF/MACC and OPAC (ECMWF/MACC와 OPAC자료를 이용한 시너지 에어로솔 모델 산출)

  • Lee, Kwon-Ho;Lee, Kyu-Tae;Mun, Gwan-Ho;Kim, Jung-ho;Jung, Kyoung-Jin
    • Korean Journal of Remote Sensing
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    • v.34 no.6_1
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    • pp.857-868
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    • 2018
  • The microphysics and spatio-temporal distribution of atmospheric aerosols are responsible for estimating the optical properties at a given location. Its accurate estimation is essential to plan efficient simulation for radiative transfer. For this sake, synergetic use of reanalysis data with optics database was used as a potential tool to precisely derive the aerosol model on the basis of the major representative particulates exist within a model grid. In detail, mixing of aerosol types weighted by aerosol optical depth (AOD) components has been developed. This synergetic aerosol model (SAM) is spectrally extended up to $40{\mu}m$. For the major aerosol event cases, SAM showed that the mixed aerosol particles were totally different from the typical standard aerosol models provided by the radiative transfer model. The correlation among the derived aerosol optical properties along with ground-based observation data has also been compared. The current results will help to improve the radiative transfer model simulation under the real atmospheric environment.

Guidelines for dental clinic infection prevention during COVID-19 pandemic (코로나 바이러스 대유행에 따른 치과 의료 관리 가이드라인)

  • Kim, Jin
    • Journal of Korean Academy of Dental Administration
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    • v.8 no.1
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    • pp.1-7
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    • 2020
  • Dental settings have unique characteristics that warrant specific infection control considerations, including (1) prioritizing the most critical dental services and provide care in a way that minimizes harm to patients due to delayed care, or harm to personnel from potential exposure to persons infected with the COVID-19 disease, and (2) proactively communicate to both personnel and patients the need for them to stay at home if sick. For health care, an interim infection prevention and control recommendation (COVID-19) is recommended for patients suspected of having coronavirus or those whose status has been confirmed. SARS-CoV-2, which is the virus that causes COVID-19, is thought to be spread primarily between people who are in close contact with one another (within 6 feet) through respiratory droplets that are produced when an infected person coughs, sneezes, or talks. Airborne transmission from person-to-person over long distances is unlikely. However, COVID-19 is a new disease, and there remain uncertainties about its mode of spreads and the severity of illness it causes. The virus has been shown to persist in aerosols for several hours, and on some surfaces for days under laboratory conditions. COVID-19 may also be spread by people who are asymptomatic. The practice of dentistry involves the use of rotary dental and surgical instruments, such as handpieces or ultrasonic scalers, and air-water syringes. These instruments create a visible spray that can contain particle droplets of water, saliva, blood, microorganisms, and other debris. While KF 94 masks protect the mucous membranes of the mouth and nose from droplet spatter, they do not provide complete protection against the inhalation of airborne infectious agents. If the patient is afebrile (temperature <100.4°F)* and otherwise without symptoms consistent with COVID-19, then dental care may be provided using appropriate engineering and administrative controls, work practices, and infection control considerations. It is necessary to provide supplies for respiratory hygiene and cough etiquette, including alcohol-based hand rub (ABHR) with 60%~95% alcohol, tissues, and no-touch receptacles for disposal, at healthcare facility entrances, waiting rooms, and patient check-ins. There is also the need to install physical barriers (e.g., glass or plastic windows) in reception areas to limit close contact between triage personnel and potentially infectious patients. Ideally, dental treatment should be provided in individual rooms whenever possible, with a spacing of at least 6 feet between the patient chairs. Further, the use of easy-to-clean floor-to-ceiling barriers will enhance the effectiveness of portable HEPA air filtration systems. Before and after all patient contact, contact with potentially infectious material, and before putting on and after removing personal protective equipment, including gloves, hand hygiene after removal is particularly important to remove any pathogens that may have been transferred to the bare hands during the removal process. ABHR with 60~95% alcohol is to be used, or hands should be washed with soap and water for at least 20 s.

A Study on Occupational Stress and Coping, Turnover, Knowledge and Practice of Infection Control in Dental Hygienists of COVID-19

  • Kwon, Hye-Rin;Gil, A-Young;Kim, Ji-Min;No, Ji-Seon;Park, Ga-Bin;Oh, Ji-Yune;Lee, Na-Kyung;Kim, Seol-Hee
    • Journal of dental hygiene science
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    • v.21 no.4
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    • pp.233-242
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    • 2021
  • Background: The importance of infection with COVID-19 is being emphasized in dentistry with high risks such as aerosols. The purpose of this study is to investigate the knowledge and practice of infection control, stress and coping, and turnover of dental hygienists. Methods: Questionnaire was conducted knowledge and practice of infection control, occupational stress and coping, turnover. Survey data was investigated about 149 dental hygienists from February to March 2021 Data were analyzed t-test, ANOVA, Pearson's correlation using statistical programs of PASW Statistics ver. 21.0. Results: Regarding occupational stress, relationship conflict was higher in the group with less than 2 years of experience (p<0.05). Job anxiety, organizational system, inadequate compensation, and workplace culture were highly surveyed in the 3 to 5 year of experience. The group with more than 6 years of experience had the highest perception of lack of job autonomy (p<0.05). The group with higher knowledge of infection control had lower mean inappropriate rewards and stress (p<0.05). The group with high infection control performance had a lower average in items such as job instability, organizational system, inadequate compensation, workplace culture, and stress. And problem-focused coping ability was found to be high (p<0.05). Infection control knowledge and performance were positively correlated (r=0.251, p<0.01), infection control practice and stress were negatively correlated (r=-0.264, p<0.01), and stress and emotional coping were positively correlated (r=0.367, p<0.01). Stress was positively correlated with turnover rate (r=0.549, p<0.01). Conclusion: Infection control training was required to reduce occupational stress. Occupational stress was highly correlated with turnover, a holistic and systemic organizational operation and improvement of the quality of medical care were required to reduce stress.

Characterization of fine particulate matter during summer at an urban site in Gwangju using chemical, optical, and spectroscopic methods (화학적·광학적·분광학적 방법을 이용한 광주 도심지역 여름철 초미세먼지의 특성)

  • Son, Se-Chang;Park, Tae-Eon;Park, Seungshik
    • Particle and aerosol research
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    • v.17 no.4
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    • pp.91-106
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    • 2021
  • Daily PM2.5 was collected during summer period in 2020 in Gwangju to investigate its chemical and light absorption properties. In addition, real-time light absorption coefficients were observed using a dual-spot 7-wavelength aethalometer. During the study period, SO42- was the most important contributor to PM2.5, accounting for on average 33% (10-64%) of PM2.5. The chemical form of SO42- was appeared to be combination of 70% (NH4)2SO4 and 30% NH4HSO4. Concentration-weighted trajectory (CWT) analysis indicated that SO42- particles were dominated by local pollution, rather than regional transport from China. A combination of aethalometer-based and water-extracted brown carbon (BrC) absorption indicated that light absorption of BrC due to aerosol particles was 1.6 times higher than that due to water-soluble BrC, but the opposite result was found in absorption Ångström exponent (AAE) values. Lower AAE value by aerosol BrC particles was due to the light absorption of aerosol BrC by both water-soluble and insoluble organic aerosols. The BrC light absorption was also influenced by both primary sources (e.g., traffic and biomass burning emissions) and secondary organic aerosol formation. Finally the ATR-FTIR analysis confirmed the presence of NH4+, C-H groups, SO42-, and HSO42-. The presence of HSO42- supports the result of the estimated composition ratio of inorganic sulfate ((NH4)2SO4) and bisulfate (NH4HSO4).

Characterization of fine organic aerosols from biomass burning emissions using FTIR method (분광학적 방법을 이용한 바이오매스 연소 배출 유기 입자의 화학적 특성)

  • Son, Se-Chang;Park, Tae-Eon;Park, Seungshik
    • Particle and aerosol research
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    • v.17 no.4
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    • pp.125-132
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    • 2021
  • Fresh PM2.5 smokes emitted from combustion of four biomass materials (pellet, palm fruit fiber (PFF), PKS, and sawdust) in a laboratory-controlled environment were characterized using an attenuated total reflectance-fourier transform infrared (ATR-FTIR) technique. In smoke samples emitted from combustion of pellets, PFF and PKS, which is being used as boiler fuels for greenhouses in rural areas, the organic carbon/elemental carbon (OC/EC) ratios in PM2.5 were very high (14.0-35.5), whereas in sawdust smoke samples they were significantly low (<4.0) due to the combustion method close to flaming combustion. ATR-FTIR analysis showed that OH(3400-3250 cm-1), CH3(2958-2840 cm-1), CH2(2910 cm-1 and 2850 cm-1), ketone(1726-1697 cm-1), C=C(1607-1606 cm-1 and 1515-1514 cm-1), lignin (1463-1462 cm-1 and 1430-1428 cm-1) and -NO2(1360-1370 cm-1) peaks were identified in all biomass burning (BB) smoke samples. However, additional peaks appeared depending on the type of biomass. Among the four types of biomass materials, an additional peak of the methylene group CH3(2872-2870 cm-1) appeared only in PFF and PKS smoke samples, and a peak of C=O(1685 cm-1) was also confirmed. And in the case of PKS smoke samples, a peak of aromatic C=C(1593 cm-1 and 1476 cm-1) that did not appear in other BB samples was also observed. This indicates that the molecular structure of organic compounds emitted during BB differs depending on the type of biomass materials. The results of this study are expected to provide valuable information to more specifically reveal the effect of BB on PM2.5 collected in the atmospheric environment.

Microbial Metagenome of Airborne Particulate Matter: Methodology, Characteristics, and Influencing Parameters (대기입자상물질의미생물메타게놈: 분석방법, 특성및영향인자)

  • Kang, Sookyung;Cho, Kyung-Suk
    • Microbiology and Biotechnology Letters
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    • v.50 no.2
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    • pp.165-192
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    • 2022
  • The microbial metagenome characteristics of bioaerosols and particulate matter (PM) in the outdoor atmospheric environment and the effects of climate and environmental factors on the metagenome were analyzed. The concentrations of bacteria and fungi in bioaerosols and PM were determined by sampling different regions with different environmental properties. A variety of culture-independent methods were used to analyze the microbial metagenome in aerosols and PM samples. In addition, the effects of meteorological and environmental factors on the diversity and metagenomes of bacteria and fungi were investigated. The survival, growth, and dispersal of the microorganisms in the atmosphere were markedly affected by local weather conditions and the air pollutant concentration. The concentration of airborne microorganisms increased as the temperature increased, but their concentration decreased in summer, due to the effects of high temperatures and strong ultraviolet rays. Humidity and microbial concentration were positively correlated, but when the humidity was too high, the dispersion of airborne microorganisms was inhibited. These comprehensive data on the microbial metagenome in bioaerosols and PM may be used to understand the roles and functions of microorganisms in the atmosphere, and to develop strategies and abatement techniques to address the environmental and public health problems caused by these microorganisms.