Asian Dust Events Research Articles

Characterization of Organic Aerosol Particles Observed during Asian Dust Events in Spring 2010

Between 20 March and 4 April, 2010, 24-hr PM2.5 measurements were carried out at an urban site in Gwangju, Korea, to examine the variations in the composition of its chemical constituents among dust storm (DS) events, haze pollution, and typical sampling (TS) conditions. A very heavy Asian DS (DS1) and a minor DS (DS2) occurred at the site on 20 and 23 March, 2010, respectively. The concentrations of organic matter, NO3–, SO42–, and the predicted crustal material made a contribution to the observed PM2.5 of 12.9, 9.7, 12.9, and 36.9% for DS1, 23.8, 17.1, 9.9, and 29.7% for DS2, and 24.9, 20.2, 10.3, and 17.6% for the haze event, respectively. Over the study period, the water-soluble organic carbon (WSOC)/OC and hydrophilic WSOC (WSOCHPI)/WSOC ratios ranged from 0.35 to 0.54 and from 0.15 to 0.61, respectively, with the highest ratios occurring during DS1. The concentration of WSOCHPI during DS1 was about 2–3 times higher than that during the TS period. The strong correlation between WSOC/OC and WSOCHPI/WSOC (R2 = 0.84) clearly indicates that the increase in the WSOC/OC ratio can be attributed to the increased concentration of WSOCHPI, suggesting that the aerosol sample collected during DS1 was more aged or atmospherically processed than the samples collected during the TS. In addition to the association between the WSOC/OC and WSOCHPI/WSOC ratios, strong correlations between the oxalate and SO42– concentrations (R2 = 0.74), and between the WSOCHPI and SO42– concentrations (R2 = 0.69), suggest that the WSOCHPI observed at the site was produced by atmospheric transformation processes similar to those seen with SO42– and oxalate. In contrast, the hydrophobic WSOC (WSOCHPO) concentration dominated in the other sampling periods, except for DS1, and accounted for 71.1–84.7% of WSOC. Based on the results of previous studies, the higher WSOCHPO/WSOC ratio during the TS indicates that the primary combustion emissions were important sources of the WSOCHPO fraction at this site.

Numerical simulation and evaluation of Asian dust events observed in Mongolia in spring 2011

The Asian dust forecasting model, Mongolian Asian Dust Aerosol Model (MGLADAM), has been operated by the National Agency for Meteorology and Environmental Monitoring of Mongolia since 2010, for the forecast of Asian dust storms. In order to evaluate the performance of the dust prediction model, we simulated Asian dust events for the period of spring 2011. Simulated features were compared with observations from two sites in the dust source region of the Gobi desert in Mongolia, and in the downstream region in Korea. It was found that the simulated wind speed and friction velocity showed a good correlation with observations at the Erdene site (one of the sites in the Gobi desert). The results show that the model is proficient in the simulation of dust concentrations that are within the same order of magnitude and have similar start and end times, compared with PM10 observed at two monitoring sites in the Gobi regions. Root Mean Square Error (RMSE) of the dust simulation ranges up to 200 μg m−3 because of the high concentrations in source regions, which is three times higher than that in the downstream region. However, the spatial pattern of dust concentration matches well with dust reports from synoptic observation. In the downwind regions, it was found that the model simluated all reported dust cases successfully. It was also found that the RMSE in the downwind region increased when the model integration time increased, but that in the source regions did not show consistent change. It suggests that MGLADAM has the potential to be used as an operational dust forecasting model for predicting major dust events over the dust source regions as well as predicting transported dust concentrations over the downstream region. However, it is thought that further improvement in the emission estimation is necessary, including accurate predictions in surface and boundary layer meteorology. In the downwind regions, background PM10 concentration is considerably affected by other aerosol species, suggesting that a consideration of anthropogenic pollutants will be required for accurate dust forecasting.

A simulation of Asian dust events observed from 20 to 29 December 2009 in Korea by using ADAM2

The Asian dust Aerosol Model 2 (ADAM2) with the MM5 meteorological model has been employed to study long-range transport process of Asian dust and to estimate dust emission, deposition (wet and dry) and concentration over the Asian dust source region and the downwind regions for dust events observed in Korea during the period of 20–29 December 2009, which is one of the dust events chosen by the 3rd Meeting of Working Group for Joint Research on Dust Sand Storm among Mongolia, China, Japan and Korea to study intensively for the development of an early warning system in Asia. It is found that the model simulates quite well the starting and ending times of dust events and the peak dust concentrations with their occurrence times both in the source region and downwind regions. The dust emission in the dust source region is found to be associated with a developing synoptic weather system accompanied with strong surface winds over the source region that usually travels east to southeastward across the source region and then turns to move northeastward toward the north western Pacific Ocean. The dust emitted in the source region is found to be split into two parts: one is transported southeastward to the East China Sea in front of the surface high pressure system and experiencing enhanced deposition due to the sinking motion induced by the southeastward traveling the surface high pressure system whereas, the other moves northeastward toward the surface low pressure system and then lifted upward to form a upper-level high dust concentration layer that results in a favorable condition for the long-range transport of dust. It is also found that the maximum ten-day total dust emission of about 23 t km−2 occurs in the domain Northwestern China (NWC). However, the maximum ten-day total dust deposition of 21 t km−2 with the maximum mean surface concentration of 555 μg m−3 and the column integrated mean concentration of 2.9 g m−2 occurs in the domain Central-northern China (CNC). The column-integrated PM10 concentration is found to increase toward northeastward especially in the domain North northeastern China (NNEC) due to the upper-level transported high PM10 concentration. The ten-day total dust deposition, mean surface PM10 and column integrated PM10 concentrations in the downwind domains are found to decrease away from the source region from 2.44 t km−2, 112 μg m−3 and 1.68 g m−2, respectively in the domain YES to 0.06 t km−2, 2.1 μg m−3 and 0.4 g m−2, respectively in the domain Northwestern Pacific 1 (NWP1). Much of the total dust deposition is largely contributed by wet deposition in the far downwind region of the seas while that is contributed by dry deposition in the source region.

A numerical study of the effect of frozen soil on dust emission during an East Asian dust event in December 2009

There are few dust simulation studies for East Asian dust events that took place in the wintertime, when the surface conditions of the dust source region differ from those of the springtime. The soil water turns into ice when the temperature falls below freezing, and the ice might prohibit wind erosion by increasing the binding strength between soil particles. However, the contribution of frozen soil to reducing dust outbreaks remains unclear. This study investigates the effect of frozen soil on dust emission through a case study of a severe wintertime East Asian dust event that originated on 23 and 24 December 2009 in Southern Mongolia and Inner Mongolia and reached Korea on 25 and 26 December 2009 using WRF/Chem with a new dust emission scheme. Model simulations with and without the effect of frozen soil were conducted. A temperature below 0°C and relative soil saturation exceeding 40% were used for frozen soil criteria, and the frozen soil was prohibited from emitting dust. The dust concentrations derived from the simulation without the effect of frozen soil were about three times higher than the observed PM10 concentrations, while the results from the simulation with the frozen-soil effect were quite similar to those of the observation data. The simulation of the wintertime East Asian dust event with the frozen-soil effect improved the model representation. The sensitivity tests for frozen soil indicate that the criteria of frozen soil used in this study are appropriate for this case study.

The Relationship between Skin Symptoms and Allergic Reactions to Asian Dust

Asian dust events result from displacement of atmospheric pollutants from the Chinese and Mongolian deserts, causing associated health issues throughout Northeast Asia. We investigated the relationship between skin symptoms in Asian dust events and contact allergy to Asian dust and associated metals. Increases in atmospheric levels of heavy metals such as Ni, Al, and Fe occurred during the severe Asian dust event on March 21, 2010. We conducted a case–control study (n = 62) with patch testing to compare skin symptoms on an Asian dust day with metal allergic reactions. Skin symptoms were observed in 18/62 subjects. Nine subjects with skin symptoms (group A) and 11 without (group B) were patch tested for six metals and Asian dust particles. Metal and dust samples were applied to the subjects’ backs for 2 days and the reactions were scored according to the International Contact Dermatitis Research Group guidelines. Differences in the positive rates between the groups were analyzed. Skin reactions to ferric chloride (p = 0.015), aluminum chloride (p = 0.047), nickel sulfate (p = 0.008), and Asian dust particles (p = 0.047) were more common in group A than in group B. Skin symptoms during Asian dust events may be allergic reactions to Asian dust particle-bound metals.

Asian dust and daily all-cause or cause-specific mortality in western Japan

ObjectiveDesert dust, which is included in course particles, is considered to have potential toxicity. The effect modification of desert dust on associations between anthropogenic air pollution and mortality has been...

Determination of Heavy Metal Distribution in PM10During Asian Dust and Local Pollution Events Using Laser Induced Breakdown Spectroscopy (LIBS)

Hourly concentrations of heavy metals in PM10 samples were continuously measured using Laser Induced Breakdown Spectroscopy (LIBS) to determine the metal distribution among Asian Dust (AD) events, local pollution events, and nonevents. Quantification of metals was performed by establishing a calibration line between 24 h average data determined by the ICP-MS after filter sampling and LIBS intensity data. It was found that in AD and local pollution events, significant anthropogenic heavy metals, such as Pb, Cr, Ni, and Zn, were detected compared to a nonevent, and that crustal elements (e.g., Al, Ca, Mg) were more abundant in the AD events than those in a local pollution event or nonevent. The AD events were further classified into “nonpolluted AD” and “polluted AD” events, depending on the air mass transport pathways. During “polluted AD” events where the air mass passed over industrialized zones, both crustal (Al, Ca, Mg) and anthropogenic (Cr, Ni, Zn) metal elements simultaneously increased with time, suggesting that the AD particles could not only include crustal elements but also have a significant quantity of anthropogenic heavy metals. The concentration of anthropogenic heavy metals (Cr + Pb + Zn) was the highest in the AD3 event in order of AD3 (polluted) > AD1 (polluted) > local pollution > AD2 (nonpolluted). However, the PM10-weighted value (Cr + Pb + Zn/PM10) was the highest in the local pollution event where concentrations of only anthropogenic heavy metals increased. Also, the hourly LIBS data was successfully used to discriminate metal contributions between AD events and local pollution events or among AD events by employing a chemometric method. Copyright 2012 American Association for Aerosol Research

Long-range transported Asian Dust and emergency ambulance dispatches

Asian Dust (AD) particles transported from source areas contribute to sharp increases in coarse particles in Japan. We examined the association of exposure to AD events with emergency ambulance dispatches in Nagasaki city. We also examined whether AD transported at different altitude routes from source areas influenced dispatch rates. Using lidar (light detection and ranging), we determined moderate AD days (0.066/km <dust extinction coefficient ≤0.105/km) and heavy AD days (0.105/km <dust extinction coefficient). We applied a time-stratified case-crossover analysis to estimate the association between AD days and emergency ambulance dispatches. There were 9,070 dispatches from March to May during 2003–2007. The heavy AD events at cumulative lag0–3 were associated with an increase in emergency dispatches due to all causes by 12.1% (95% confidence interval (CI), 2.3, 22.9) and an increase for those due to cardiovascular diseases by 20.8% (95% CI: 3.5, 40.9). We categorized 31 AD days based on backward trajectory analyses into AD days with lower altitude routes and those with higher altitude routes. We observed a greater increase in emergency ambulance dispatches on AD days with lower altitude routes compared with those on AD days with higher altitude routes although the difference was not significant (p for interaction 0.49). These results have shown that exposure to high AD particle levels could increase emergency ambulance dispatches due to illnesses such as cardiovascular stress, and that AD traveling through different routes may have different health effects.

2009-2010년 봄철 심한 황사 사례에 대한 에어러솔 크기 분포와 광학적 특성

Measurements of <TEX>$PM_{10}$</TEX> mass concentration, aerosol light scattering and absorption coefficients as well as aerosol size distribution were made to characterize the aerosol physical and optical properties at the two Korean WMO/GAW regional stations, Anmyeondo and Gosan. Episodic cases of the severe Asian dust events occurred in spring of 2009-2010 were studied. Results in this study show that the aerosol size distributions and optical properties at both stations are closely associated with the dust source regions and the transport routes. According to the comparison of the <TEX>$PM_{10}$</TEX> mass concentration at both stations, the aerosol concentrations at Anmyeondo are not always higher than those at Gosan although the distance from the dust source region to Anmyeondo is closer than that of Gosan. The result shows that the aerosol concentrations depend on the transport routes of the dust-containing airmass. The range of mass scattering efficiencies at Anmyeon and Gosan was 0.50~1.45 and <TEX>$0.62{\sim}1.51m^2g^{-1}$</TEX>, respectively. The mass scattering efficiencies are comparable to those of the previous studies by Clarke et al. (2004) and Lee (2009). It is noted that anthropogenic fine particles scatter more effectively the sunlight than coarse dust particles. Finally, we found that the aerosol size distribution and optical properties at Anmyeondo and Gosan show somewhat different properties although the samples for the same dust_episodic events are compared.

Adverse Health Effects of Asian Dust Particles and Heavy Metals in Japan

Asian dust events are now considered an environmental problem rather than a natural seasonal phenomenon. In this study, we evaluated the associations between daily adverse health effects and Asian dust events in Yonago, Japan. Participants included 54 healthy volunteers, who were distributed survey sheets on nasal, ocular, respiratory, and skin effects in February 2009. Moreover, we collected meteorological and air pollutant (nitric oxide, sulfur dioxide, suspended particulate matter) data and determined pollen and metallic element concentrations in total suspended particulates. Both soil-derived metals (Fe, Ca, Al) and contaminating metals (Pb, Cr, Mn, Ni, Zn) were significantly increased on Asian dust days. Multiple regression analyses showed that the score of the skin effect was significantly associated with the levels of suspended particulate matter and Ni. The results show that increased air pollutants on Asian dust days may have skin effects.

The relationship between satellite-derived primary production and vertical mixing and atmospheric inputs in the Yellow Sea cold water mass

This study examined the spatiotemporal distribution of primary production and its relationship with climatic and environmental factors in the south Yellow Sea Cold Water Mass (YSCWM) from January 1998 to December 2007. Primary production was estimated from satellite ocean color data. The annual primary production cycle was characterized by two peaks: a larger one in April (spring) and a smaller one in November (fall). The first empirical orthogonal function (EOF) mode of monthly primary production showed that two peaks occurred separately in spring and fall most years and two high primary production regions appeared in the middle of the YSCWM. The first EOF mode of monthly and spring primary production revealed a high primary production value in spring 2006. Correlation and multiple linear regression analyses suggested that primary production was influenced by the mixed layer depth (MLD), upward sea water velocity, aerosol index, and precipitation. The consistency between the first EOF mode of spring primary production and the aerosol index suggested that Asian dust events are important in the interannual variation of primary production in spring, especially in 2006.

Simulating dry deposition fluxes of PM10 and particulate inorganic nitrogen over the eastern China seas during a severe Asian dust event using WRF-Chem model

A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19–25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.

2009년 서울지역 황사 및 고농도 미세먼지 사례 시 미세먼지의 화학성분 특성

This study aimed to show the chemical characteristics of <TEX>$PM_{10}$</TEX> and <TEX>$PM_{2.5}$</TEX> during Asian dust (AD) events and high PM episodes observed in Seoul. Time-resolved chemical composition of <TEX>$PM_{10}$</TEX> or <TEX>$PM_{2.5}$</TEX> was monitored in 1 hour interval using ambient ion monitor, semi-continuous carbon monitor, and on-line XRF spectrometer at Seoul intensive monitoring site in 2009. Considering that AD events were classified into three different cases according to the source area and pathway, the concentrations of ammonium-sulfate and trace metal components were relatively high when the AD were occurred in Gobi and inner-mongolia and transported across the Bohai bay. In addition, the influence of alkaline dust, which carried from saline land located in the northeastern China, was observed when the AD was originated from Gobi, inner-mongolia, and Manchuria. Except AD events, the high PM episodes observed in Seoul were impacted by various anthropogenic sources such as biomass burning, motor vehicle, oil combustion and road dust.

황사 발생 기간 낙하먼지에 포함된 미생물의 분포 및 특성

황사는 중국과 몽골의 사막지역과 중국 황하 중 상류의 황토지대에서 바람에 의해 대기 중에 부유한 미세먼지가 상층 바람을 타고 멀리까지 날아가는 기상 현상을 말한다. 황사 먼지는 bioaerosol을 포함하며 미생물의 운반체로 작용할 수 있다. 따라서 본 연구에서는 황사 발생 기간과 황사가 없는 기간 동안 각각 포집한 낙하먼지에서 미생물의 농도와 종 조성을 비교하고자 하였다. 2008년 2월부터 4월까지 울산 지역의 한 지점에서 직경 200 mm의 강수량계를 사용하여 낙하먼지를 포집하였으며, 조사 기간 동안 울산 지역에서 황사 현상은 3월 2일과 3일에 걸쳐 한번 발생하였다. 낙하먼지에 포함된 세균의 농도는, 황사 기간 동안 포집한 시료에서 황사가 없는 기간의 시료에 비해 크게 높았다. 하지만, 낙하먼지의 진균 농도는 비 황사 기간에 비해 황사 기간 동안 유의성 있게 증가하지 않았으며, 조사 기간 동안 세균에 비해 상대적으로 일정한 수준을 유지하였다. 낙하먼지 시료로부터 분리한 45개 세균의 16S rRNA 유전자 염기 서열을 분석하였으며, 이들 세균은 Bacillus 속의 B. amyloliquefaciens, B. aryabhattai, B. atrophaeus, B. licheniformis, B. megaterium, B. methylotrophicus, B. pumilus, B. sonorensis, B. subtlis, B. vallismortis와 Staphylococcus 속의 S. epidermidis, S. succinus로 확인되었다. 진균의 경우 Mucor 속, Alternaria 속, Cladosporium 속, Aspergillus 속 등을 황사 기간 및 비 황사 기간의 시료에서 모두 확인할 수 있었다. Bacillus 속과 같은 내생포자를 형성하는 세균이 진균(포자)에 비해 황사 먼지에의 부착 및 이동과 더 연관이 있는 것으로 보인다. 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.

황사의 비구형성이 에어러솔 광학적 두께 산출에 미치는 영향 연구

In this study, we investigate the effects of elliptical shape of Asian dust particles on the estimation of aerosol optical depth by implementing T-matrix method into WRF/Chem Dust Model. The phase function calculated by assuming elliptical particle shape near <TEX>$110{\sim}160^{\circ}$</TEX> of scattering angle showed about 20 times larger than that calculated by assuming spherical particle shape. Significant difference of extinction efficiency was found with an increase of size parameter and aspect ratio. From the simulations of two Asian dust events occurred on 1 April 2007 and 16 March 2010, we found that the difference of extinction efficiency between elliptical and spherical particle shape was about 5~8%. The aerosol optical depth calculated by assuming elliptical particle shape with 1.6, 1.4 and 1.2 of aspect ratio was about <TEX>$4.0{\pm}0.5%$</TEX>, <TEX>$2.0{\pm}0.2%$</TEX>, and <TEX>$1.0{\pm}0.1%$</TEX> larger than those estimated by assuming spherical particle shape.

Factors affecting the level and pattern of polycyclic aromatic hydrocarbons (PAHs) at Gosan, Korea during a dust period

Polycyclic aromatic hydrocarbons (PAHs) in both gas and total suspended particles were measured at Gosan, Jeju Island in Korea, a remote background site, for 15 days (March 29–April 12, 2002). During the sampling period, a severe three-day Asian dust (AD) event originating from Mongolia and northern China was observed throughout the Korean Peninsula and Jeju Island. In addition, pollution (PO) and normal (NO) periods were also identified based on the levels of anthropogenic pollutants. Despite a large difference of PM10 concentrations between the AD and PO periods, the levels of particulate PAHs in both periods were comparable (2.7±1.0 and 2.4±0.5ngm−3, respectively) since they were determined by the concentration of anthropogenic PM2.5 transported from industrial areas of China. In the AD period, the level of gaseous PAHs, which were mostly from local sources, was the lowest due to strong winds; the gas/particle partitioning was close to equilibrium as the effect of long-range transport was manifested. The results of backward air trajectories, correlation analysis, and diagnostic ratios show that long-range transport of particulate PAHs produced by coal/biomass burning in China could strongly affect the levels and patterns of PAHs at Gosan, Korea.

Relationship between water-soluble ions in PM2.5 and their precursor gases in Seoul megacity

In this study, fine-particle (PM2.5) ionic composition in the city of Seoul was investigated using short-term measurement data (1 h interval) collected during the year 2010. The partitioning of semi-volatile inorganic species and phase state of aerosols were studied using ISORROPIA II thermodynamic equilibrium model. The analysis of ionic composition identified the relative dominance of NO3−, SO42−, and NH4+ in the fine particles. The presence of strong correlation between these components indicates similarity of their formation pathways. Seasonal patterns of these ionic components and their gas-phase precursors were somewhat different from each other. The observed SO42−/SO2 mass ratio indicated a significant role of the gas-phase oxidation of SO2 (to H2SO4) in the SO42− formation. Moreover, both SO42− and NO3− were almost completely neutralized by NH4+ to form (NH4)2SO4 and NH4NO3. The formation of NO3− aerosol would be ammonia-sensitive (i.e., deficit ammonia), as evidenced by smaller total ammonia concentration than the sum of total sulfate and nitrate concentrations. The uptake of SO2 on dust particles during Asian dust event is also likely to exert controls on SO42− concentrations.

Analysis of Impact Factors on the Variation of PM10 Concentration in Seoul, Korea

To identify the primary factor affected the decreased PM 10 concentration in Seoul which is the capital city of Korea, wind speed and emissions in 2003 and 2004 were analyzed. The level of air pollution is intense in Seoul and continually increased since the late 1990s. However the concentration of PM 10 has been greatly declined recently. In particular, the concentration of PM 10 decreased 14% in 2003 and 2004 excluding the Asian dust periods. It is suggested that the major factors for the decrease are differences in wind speed between the two years and the period of constant breeze. In 2003, intense Asian dust events happened frequently and it increased the concentration of total PM 10 . The intense dust events were influence by the speed and duration of the wind. It is considered that the meteorological condition was the primary drive for the change of the concentration of PM 10 . The decreased emissions seem to be the additional factor for the change in the concentration of PM 10 .

겨울철 황사 모의시 황사배출량 산정식과 입력자료의 평가: 2007년 12월 29일 황사사례 연구

A case study was conducted for a severe wintertime dust event that occurred on December 29, 2007 in Korea. Three different dust emission schemes, namely, those of Marticorena and Bergametti (1995), Lu and Shao (1999), and Shao (2004) (hereinafter, referred to MB, LS, and S04 schemes, respectively) were implemented in Weather Research Forecast with Chemistry (WRF/Chem) to assess their performance in simulating wintertime Asian dust events. WRF/Chem simulation reproduces dust emission over Mongolia on December 27 and 28, 2007 and the onset timing of the dust event in Korea well. There is, however, a huge difference among the estimated dust emission amounts for the three schemes; the dust concentration derived by MB scheme is 6 times larger than that from LS scheme. The three schemes overestimate dust concentrations when comparing to observed surface-level mass concentrations in Ganghwa, Seoul, and Yeongwol. This discrepancy is thought to be mainly due to the overestimated model winds and the surface condition such as snow cover fraction, which did not adequately represent the real conditions. Considering frozen soil effect on dust emission, the model results are comparable with observation data: it is important to consider frozen soil in simulating wintertime dust events.

Effects of Asian Dust and Spherical Particles Exposure on Human Health and Allergic Symptom, Fukuoka, Japan

Asian dust arise in arid areas of China and spread over large areas diminishing the particle size on East China, Korea and Japan. People Asia region have been exposed to the particles which contained various chemical species and suffered from the potentially hazardous effect on respiratory symptoms. Moreover spherical particles including SO42- and NO3- are transported too. We have investigated into effects of Asian dust and spherical particles on human health especially allergic symptom.