Dust Period Research Articles

Steric 모드의 침강장-흐름 분획법을 이용한 황사의 특성분석

황사입자들은 수 나노미터에서 수 마이크론 사이의 크기를 가지는 것으로 알려져 있다. 황사가 환경 및 인체 건강에 미치는 영향은 황사 입자의 크기에 의존한다. 입자가 작을수록 멀리까지 이동하며, 인체의 호흡기관 깊숙이 침투한다. 침강장-흐름 분획법(sedimentation field-flow fractionation, SdFFF)은 채널 내 포물선형태의 흐름(parabolic flow profile)과 외부에서 가해지는 원심력의 상호작용을 이용하여 나노 및 마이크론 크기의 입자들의 분리를 제공한다. 본 연구에서는 황사입자의 크기별 분리와 특성분석을 위한 steric 모드 침강장-흐름 분획법(Sd/StFFF)의 응용 가능성을 테스트하였다. 이를 위하여 다양한 Sd/StFFF 파라미터들을(유속, stop-flow time, 원심력의 세기, 등) 최적화 하였다. Sd/StFFF 보정곡선의 <TEX>$R^2$</TEX>값은 0.9983으로 높은 직선성을 보였으며, 실험결과는 Sd/StFFF가 마이크론 입자의 크기별 분리에 우수함을 보여주었다. 광학현미경(optical microscopy, OM)을 이용하여 황사입자들의 크기와 모양을 조사하였다. 황사가 진할 때에는 약할 때보다 입자크기가 증가함을 보여주었다. 또한 비가 올 때에는 건조할 때보다 입자크기가 감소하였는데, 이는 입자 표면에 흡착되어 있는 성분들이 빗물에 의해 제거되었기 때문인 것으로 보여진다. 본 연구의 결과는 Sd/StFFF가 황사와 같이 환경입자의 크기특성분석에 유용함을 보여준다. Asian dust particles are known to have sizes ranging from a few nanometers up to about a few micrometers. The environmental and health effects depend on the size of the dust particles. The smaller, the farther they are transported, and the deeper they penetrate into the human respiratory system. Sedimentation field-flow fractionation (SdFFF) provides separation of nano to microparticles using a combination of centrifugal force and parabolic laminar flow in a channel. In this study, the steric mode of SdFFF (Sd/StFFF) was tested for size-based separation and characterization of Asian dust particles. Various SdFFF experimental parameters including flow rate, stop-flow time and field strength of the centrifugal field were optimized for the size analysis of Asian dust. The Sd/StFFF calibration curve showed a good linearity with <TEX>$R^2$</TEX> value of 0.9983, and results showed an excellent capability of Sd/StFFF for a size-based separation of micron-sized particles.The optical microscopy (OM) was also used to study the size and the shape of the dust particles. The size distributions of the samples collected during a thick dust period were shifted towards larger sizes than those of the samples collected during thin dust periods. It was also observed that size distribution of the sample collected during dry period shifts further towards larger sizes than that of the samples collected during raining period, suggesting the sizes of the dust particle decrease during raining periods as the components adsorbed on the surface of the dust particles were removed by the rain water. Results show Sd/StFFFis a useful tool for size characterization of environmental particles such as the Asian dust.

Comparison of Chemical Compositions of Size-segregated Atmospheric Aerosols between Asian Dust and Non-Asian Dust Periods at Background Area of Korea

diameter). As well in the elemental analysis of aerosols, the major soil-originated Al, Fe, Ca, and others showed prominently high concentrations in the coarse particle fraction, whereas the anthropogenic S and Pb were relatively high in the fine particle fraction. From the comparison of aerosol compositions between Asian dust and non-Asian dust periods, the concentrations of the soil-originated species such as nss-Ca 2+ , Al, Ca, Fe, Ti, Mn, Ba, Sr have increased as 2.7-4.2 times during the Asian dust periods. Meanwhile the concentrations of nssSO4 2� and NO3 � have increased as 1.4 and 2.0 times, and on the contrary NH4 + concentrations have a little bit decreased during the Asian dust periods. Especially the concentrations of both soil-originated ionic and elemental species increased noticeably in the coarse particle mode during the dust storm periods.

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.

2007년 봄철 대전지역에서 발생한 황사 및 대기부유물의 지구화학적 특성 및 중 금속의 오염도

본 연구에서는 2007년도 봄철 대전 지역에서 발생한 황사(황사 기간) 및 대기부유물(비황사 기간)의 미량원소의 지구화학적 특성과 정량적 오염정도를 평가하였다. 황사 내 미량원소의 함량은 황사발원지 토양의 평균 함량에 비하여 수십에서 수백 배 높은 함량을 보여주고 있으며, 비황사 시기의 대기부유물에서도 유사한 특성을 보이고 있어, 황사 시기뿐만 아니라 비황사 시기에도 중국으로부터 이동되는 오염물질의 영향을 받고 있음을 지시하고 있다. 입도별 미량원소의 함량은 <TEX>$PM_{2.5}$</TEX>에서 Cr, Cu, Pb, Zn, V, S, As, Cd, Co, Ni, Mo, Sb, Cs, Rb, Th, Sc, Y 등이, 그리고 TSP에서는 Zr, Sr, Ba, Li, Th, U 등의 함량이 가장 높은 것으로 나타났다. 황사의 S, Cd, Mo, Zn, Pb, Sb, Cu 및 Zr 함량은대기부유물과 큰 차이를 보이지 않으나, 대기오염으로 부화가 발생하지 않는 Li, Cs, Co, U, Cr, Ni, Rb, V, Th, Y, Sr, Sc 등은 황사에서 2-4.2배 높아졌다. 그러므로 이들 원소들을 황사발생의 지시원소로 사용할 수 있으며, 특히 Sr, V, Cr 및 Li 등은 황사 발생을 판단하기 위한 지시원소로 사용하기에 적합한 것으로 보인다. 한편 황사의 이동경로에 따른 미량원소의 함량을 살펴본 결과, 중국의 대도시 및 산업단지를 경유하여 국내 유입된 황사가, 북한을 경유하여 국내에 도달한 황사에 비해서, S, Cd, Zn, Pb, Cu, Mo 및 As 함량이 높게 나타나, 황사의 이동경로가 이들 미량원소 오염 여부 및 오염도를 결정하는데 중요한 역할을 하는 것으로 판단된다. 황사 및 대기부유물 내 미량원소의 부화지수(Enrichment factor)을 기준으로 오염정도를 분류한 결과, 환경재해 측면에서 가장 문제가 되는 미량원소는 S, Zn, Cu, Pb, As, Mo, Cd이며, 이들은 인간의 건강 뿐만 아니라, 오랜 기간 토양과 수계환경에 퇴적될 경우 환경오염으로 인한 주변 생태계에 해로운 영향을 미치게 될 것으로 판단된다. We evaluated the geochemical characteristics and their potential pollution of Asian Dusts in Daejeon, Korea during spring 2007. Compared with the chemical compositions of soils in source area of Asian Dust, those of aerosols in Daejeon were enriched with trace elements (ten to hundred fold), inferring that pollutants from China have affected on local environment in adjoining country such as Korea. Chemical analysis of aerosols during Asian dust showed that fine particles (<TEX>$PM_{2.5}$</TEX>) contained high contents of trace elements such as Cr, Cu, Pb, Zn, V, S, As, Cd, Co, Ni, Mo, Sb, Cs, Rb, Th, Sc and Y. In the case of TSP (Total Suspended Particle), Zr, Sr, Ba, Li, Th and U were contained much more than other trace elements. The contents of some elements (i.e. Li, Cs, Co, U, Cr, Ni, Rb, V, Th, Y, Sr and Sc) in aerosols collected in Asian Dust period, which are not likely enriched by air pollutants, were higher (2 - 4.2 fold) than those in Non Asian Dust period, indicating that these elements could be used as indicator elements for determining the occurrence of Asian Dust phenomena (especially, Sr, V, Cr & Li). In the case of Asian Dust coming through the big cities and/or industrial areas of China, the domestic aerosols had higher contents of trace elements (such as S, Cd, Zn, Pb, Cu, Mo and As) than those from Northeastern China via North Korea, indicating that the transportation courses of air mass are very important to determine the pollution degrees. Using the enrichment factors of trace elements in aerosols during Asian Dust and Non Asian Dust, we identified that some elements (i.e. S, Zn, Cu, Pb, As, Mo and Cd) were most problematic in terms of environmental hazard aspects, and these elements could affect adverse effects on human health as well as ecosystem and surface environment (soil and water) through long-lived precipitation.

Long-term dust climatology in the western United States reconstructed from routine aerosol ground monitoring

Abstract. This study introduces an observation-based dust identification approach and applies it to reconstruct long-term dust climatology in the western United States. Long-term dust climatology is important for quantifying the effects of atmospheric aerosols on regional and global climate. Although many routine aerosol monitoring networks exist, it is often difficult to obtain dust records from these networks, because these monitors are either deployed far away from dust active regions (most likely collocated with dense population) or contaminated by anthropogenic sources and other natural sources, such as wildfires and vegetation detritus. Here we propose an approach to identify local dust events relying solely on aerosol mass and composition from general-purpose aerosol measurements. Through analyzing the chemical and physical characteristics of aerosol observations during satellite-detected dust episodes, we select five indicators to be used to identify local dust records: (1) high PM10 concentrations; (2) low PM2.5/PM10 ratio; (3) higher concentrations and percentage of crustal elements; (4) lower percentage of anthropogenic pollutants; and (5) low enrichment factors of anthropogenic elements. After establishing these identification criteria, we conduct hierarchical cluster analysis for all validated aerosol measurement data over 68 IMPROVE sites in the western United States. A total of 182 local dust events were identified over 30 of the 68 locations from 2000 to 2007. These locations are either close to the four US Deserts, namely the Great Basin Desert, the Mojave Desert, the Sonoran Desert, and the Chihuahuan Desert, or in the high wind power region (Colorado). During the eight-year study period, the total number of dust events displays an interesting four-year activity cycle (one in 2000–2003 and the other in 2004–2007). The years of 2003, 2002 and 2007 are the three most active dust periods, with 46, 31 and 24 recorded dust events, respectively, while the years of 2000, 2004 and 2005 are the calmest periods, all with single digit dust records. Among these deserts, the Chihuahuan Desert (59 cases) and the Sonoran Desert (62 cases) are by far the most active source regions. In general, the Chihuahuan Desert dominates dust activities in the first half of the eight-year period while the Sonoran Desert in the second half. The monthly frequency of dust events shows a peak from March to July and a second peak in autumn from September to November. The large quantity of dust events occurring in summertime also suggests the prevailing impact of windblown dust across the year. This seasonal variation is consistent with previous model simulations over the United States.

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.

Influence of mineral dust transport on the chemical composition and physical properties of the Eastern Mediterranean aerosol

Bulk aerosol samples were collected from three different coastal rural sites located around the Eastern Mediterranean, (i) Erdemli (ER), Turkey, (ii) Heraklion (HR), Crete, Greece, and (iii) Tel Shikmona (TS), Israel, during two distinct mineral dust periods (October, 2007 and April, 2008) in order to explore the temporal and geographical variability in the aerosol chemical composition. Samples were analyzed for trace elements (Al, Fe, Mn, Ca, Cr, Zn, Cu, V, Ni, Cd, Pb) and water-soluble ions (Cl−, NO3−, SO42−, C2O42−, Na+, NH4+, K+, Mg2+ and Ca2+). The dust events were categorized on the basis of Al concentrations >1000 ng m−3, SKIRON dust forecast model and 3-day back trajectories into three groups namely, Middle East, Mixed and Saharan desert. ER and TS were substantially affected by dust events originating from the Middle East, particularly in October, whilst HR was not influenced by dust transport from the Middle East. Higher AOT values were particularly associated with higher Al concentrations. Contrary to the highest Al concentration: 6300 ng m−3, TS showed relatively lower AI and AOT. Al concentrations at ER were similar for October and April, whilst OMI-AI and AOT values were ∼2 times higher in April. This might be attributed to the weak sensitivity of the TOMS instrument to absorbing aerosols near the ground and optical difference between Middle East and Saharan desert dusts. The lowest enhancement of anthropogenic aerosol species was observed at HR during dust events (nssSO42−/nssCa2+ ∼ 0.13). These species were particularly enhanced when mineral dust arrived at sites after passing through populated and industrialized urban areas.

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 .

기상현상에 따른 제주지역 TSP의 이온조성 변화 특성

The ionic compositions were analyzed from the TSP samples collected at Gosan site in Jeju Island between 2000 and 2008, in order to examine the characteristics of atmospheric aerosols in accordance with the meteorological conditions. For the Asian Dust influence on the ionic compositions, the concentration ratios of <TEX>$NH_4{^+}$</TEX>, nss-<TEX>${SO_4}^{2-}$</TEX>, <TEX>$NO_3{^-}$</TEX>, and <TEX>$K^+$</TEX> were about 1.2~2.3 during Asian Dust over Non-Asian Dust periods, noticeably that of nss-<TEX>$Ca^{2+}$</TEX> was 6.8. Meanwhile the concentrations of nss-<TEX>${SO_4}^{2-}$</TEX>, <TEX>$NO_3{^-}$</TEX>, and <TEX>$NH_4{^+}$</TEX> have increased as 1.8~4.4 times during the haze event periods, and 1.0~1.6 times during the fog and mist events. The ion balance has resulted that the anionic concentrations are relatively lower than the cationic concentrations, and the discrepancy appears more decidedly as a strong Asian Dust effect. The ammonium ion balance has shown that it exists as a mixture of <TEX>$NH_4HSO_4$</TEX> and <TEX>$(NH_4)_2SO_4$</TEX>. The concentration ratios of nss-<TEX>${SO_4}^{2-}/NO_3{^-}$</TEX> for Asian Dust, haze, fog-mist, and non-event periods were respectively 1.8, 5.9, 4.6, and 2.9, which were higher values compared to those in urban areas of China as well as other domestic regions. Especially, the high ratios of sulfur oxides could be presumed by the fact that the longrange transport of air pollutants from Asia continent might affect the atmospheric aerosols of Jeju Island.

Characteristics of Atmospheric Dust Deposition in Snow on Glacier No. 72, Mount Tuomuer, China

Wind-blown mineral dust derived from the crustal surface is an important atmospheric component affecting the Earth’s radiation budget. Deposition of dust particles was measured in snow on Glacier No. 72, Mount Tuomuer, in the western Tian Shan, China. The mean concentration of dust particles (measured as the number of particles) with 0.57 < d < 26 µm in the snow pack is 706 × 103 mL−1, with a mean mass concentration of 3806 µg kg−1. Dust number size distribution showed the dominant particles with d < 2 µm, while volume size distribution showed single-modal structures having volume median diameters from 3 to 25? µm. Results were compared with data from other sites in the Tian Shan and various Northern Hemisphere sites. A backward trajectory model was also employed to examine the transport process of dust particles in this region. Most of the air mass originated from southern China, e.g., the Taklimakan Deserts in springtime, during the Asian dust period. Transport of dust from southern Chinese deserts to adjacent mountains is in agreement with a growing body of evidence on the importance of dust inputs to alpine regions.

라만 라이다의 석영 채널을 이용한 고도별 황사 농도 산출

The Light Detection and Ranging (Lidar) observation provides a specific knowledge of the temporal and vertical distribution and the optical properties of the aerosols. Unlike typical Mie scattering Lidars, which can measure backscattering and depolarization, the Raman Lidar can measure the quartz signal at the ultra violet (360 nm) and the visible (546 nm) wavelengths. In this work, we developed a method for estimating mineral quartz concentration immersed in Asian dust using Raman scattering of quartz (silicon dioxide, silica). During the Asian dust period of March 15, 16, and 21 in 2010, Raman lidar measurements detected the presence of quartz, and successfully showed the vertical profile of the dust concentrations. The satellite observations such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) confirmed spatial distribution of Asian dust. This approach will be useful for characterizing the quartz dominated in the atmospheric aerosols and the investigations of mineral dust. It will be especially applicable for distinguishing the dust and non-dust aerosols in studies on the mixing state of Asian aerosols. Additionally, the presented method combined with satellite observations is enable qualitative and quantitative monitoring for Asian dust.

Physico-chemical characteristics and environmental significance of snow deposition on Haxilegen glacier No.51 in Tian Shan, China

Snow chemistry on the glaciers of alpine regions is a good indicator of atmospheric environmental change. We examine snow chemistry in three snowpits at different altitudes on the Haxilegen Glacier No. 51, in the Kuitun River source, Tian Shan, China, during July-September 2004 to 2007. We use correlation analysis, factor analysis and sea-salt tracing methods to examine the characteristics and sources of major ions and mineral dust particles in the snow. Results show that mineral dust particles and major ions in the snow pits vary seasonally. During the Asian dust period in springtime, the concentration of mineral dust particles and major ions deposited in snow is high, while the concentration is relatively low during the non-dust period of summer and autumn. This may be caused by dust storm activity in central Asia. The order of major ionic concentrations in the snow packs was determined to be Ca2+ > SO4 2− > NH4 + > NO3 − > Cl−> Na+ > Mg2+ > K+. Ca2+ was the dominant cation; SO4 2− was the dominant anion. We find, with the exception of NO3 −, that the variabilities of ionic concentrations are highly correlated. Results show that the glacier region was significantly affected by dust activity and anthropogenic source. The major ions, especially Na+, originate from dust sources of central Asia and from the Ocean, transported by the westerly winds.

짙은 황사와 연무가 공존한 대기의 에어러솔 특성 - 2009년 3월 15~17일 -

The variation of the physicochemical properties of atmospheric aerosols in coexistence of the heavy Asian Dust and Haze observed from <TEX>$15^{th}$</TEX> to <TEX>$17^{th}$</TEX> March 2009 in Seoul was scrutinized through the mass and ion concentration observations and synoptic weather analysis. Although the ratio of PM1.0/PM10 was constant at 0.3 (which is typical during Asian Dust period in Korea) during the measurement period, both PM10 and PM1.0 mass concentrations were 3~6 times and 2~4 times higher than that of clear days, respectively. Water-soluble ion components accounted for 30~50% of PM10 and 50~70% of PM1.0 mass concentration. One of the secondary pollutants, <TEX>$NO_3^-$</TEX> was found to be associated with <TEX>$Ca^{2+}$</TEX> and <TEX>$Na^+$</TEX> in coarse mode indicating that the aerosol derived from natural source was affected by anthropogenic pollutants. While the acidity of the aerosols increased in fine mode when the stagnation of weather patterns was the strongest (March <TEX>$16^{th}$</TEX>), the alkalinity increased in coarse mode when new air masses arrived with a southwestern wind after ending a period of stagnation (March <TEX>$17^{th}$</TEX>). In the selected case, SOR (Sulfur Oxidation Ratio, <TEX>$nSO_4^{2-}/[nSO_4^{2-}+nSO_2]$</TEX>) and NOR (Nitrogen Oxidation Ratio, <TEX>$nNO_3^-/[nNO_3^-+nNO_2]$</TEX>) values of ion components were higher than the general values during Asian Dust period. These results imply that dust aerosols could be mixed with pollutants transported from China even in heavy Asian Dust cases in Korea.

Temporal characteristics of mineral dust particles in precipitation of Urumqi River Valley in Tian Shan, China: A comparison of alpine site and rural site

Physico-chemical characteristics of mineral dust particles in the precipitation at both an alpine site and a rural site were determined in the Urumqi River Valley, Tian Shan, China. Results showed that the concentration, size distribution and chemical constitutes of dust particles in the precipitation varied seasonally at both two sites, though there existed obvious differences between them. Dust particle concentration in the precipitation increased during winter and springtime, but it decreased during summer and autumn, which had a positive correlation with strengthened wind speed and Asian dust activity, but a negative correlation with the seasonal variation of the precipitation amount, implying that aerosol dust in the precipitation of Urumqi River Valley in Tian Shan was very sensitive to the seasonal change of regional atmospheric environment in central Asia. Volume-size distribution of mineral dust particles showed larger modal size in Asian dust period of winter–spring, but relatively smaller modal size in non-dust period of summer–autumn. Moreover, the average modal size and mass concentration of dust particles at the rural site are larger than that of the alpine site. Chemical constitutes of dust indicated that the precipitation chemistry was mainly controlled by regional dust storms, local dust and anthropogenic activities in central Asia. HYSPLIT Model was also employed to examine the transport process of air mass and mineral dust particles in this region.

Simulation of regional dust and its effect on photochemistry in the Mexico City area during MILAGRO experiment

Abstract Dust particles have important effects on solar radiation, climate, and photochemistry in the troposphere. Dust events were observed from March 16 to 20, 2006 in the Mexico City (MC) area during the MILAGRO (Megacity Initiative: Local and Global Research Observations) field experiment. In order to study the effects of dust aerosols on total aerosol mass concentrations and photochemistry, a regional chemical/dynamical model (Weather Research and Forecasting Chemical model version 3 – WRF/Chem-v3) was used in this study, and a dust module was implemented in the model. Analysis of model and observational data suggests that the large area of coastal dry lands to the northeast of MC is an important source of dust particles for the entire MC area. The simulations of both PM 2.5 (total particle mass with radius less than 2.5 μm) and PM 10 (total particle mass with radius less than 10 μm) concentrations are more consistent with observations than the results of the model without the dust module. During this dust period (March 16–20, 2006), the simulated dust aerosol mass accounts for about 70% of the total PM 10 aerosol mass concentrations, with a strong diurnal variation. The results also suggest that dust aerosols have important effects on actinic fluxes and therefore photochemistry, especially on hydroxyl radical (OH) and ozone (O 3 ) concentrations, in the MC area and the surrounding region. The dust particles decrease the photochemical production of OH, with a maximum reduction of 60% in the dust source region (northeast of the MC area). Near the city area, the reduction of OH concentrations is about 5–20%. The strongest effects on O 3 concentrations are near MC, where the maximum reduction of O 3 is about 10 ppbv. In the dust source region, O 3 concentrations are reduced by about 3–5 ppbv.

The effects of transported Asian dust on the composition and concentration of ambient fungi in Taiwan

This study was conducted to evaluate the effects of transported Asian dust and other environmental parameters on the levels and compositions of ambient fungi in the atmosphere of northern Taiwan. We monitored Asian dust events in Taipei County, Taiwan from January 2003 to June 2004. We used duplicate Burkard portable air samplers to collect ambient fungi before, during, and after dust events. Six transported Asian dust events were monitored during the study period. Elevated concentrations of Aspergillus (A. niger, specifically), Coelomycetes, Rhinocladiella, Sporothrix and Verticillium were noted (p < 0.05) during Asian dust periods. Botryosporium and Trichothecium were only recovered during dust event days. Multiple regression analysis showed that fungal levels were positively associated with temperature, wind speed, rainfall, non-methane hydrocarbons and particulates with aerodynamic diameters ≤10 μm (PM(10)), and negatively correlated with relative humidity and ozone. Our results demonstrated that Asian dust events affected ambient fungal concentrations and compositions in northern Taiwan. Ambient fungi also had complex dynamics with air pollutants and meteorological factors. Future studies should explore the health impacts of ambient fungi during Asian dust events, adjusting for the synergistic/antagonistic effects of weather and air pollutants.

Silica Exposure Assessment in a Mortality Study of Vermont Granite Workers

A study of past silica and respirable dust exposures in the Vermont granite industry was conducted to develop a job exposure matrix (JEM) that used 5204 industrial hygiene measurements made from 1924–2004. The construction of the JEM involved data entry from several original sources into an Excel database that was reviewed later to ensure accuracy. Exposure measurements by job or location were grouped in two broad categories of quarry or shed and then into 22 job classes. Missing exposure data by time period were computed, taking into account improvements in dust control and periods of significant reduction in dustiness. Percent free silica (α-quartz) in respirable dust was estimated to be 11.0% based on previous published studies in Vermont and on data in the current database. About 60% of all measurement data (primarily from years prior to 1972) were obtained using the impinger and expressed in millions of particles per cubic foot (mppcf), which were converted to equivalent respirable free silica concentrations using the conversion of 10 mppcf = 0.1 mg/m3 of respirable silica. For impinger data, respirable dust was calculated by multiplying respirable silica by a factor of 9.091 to reflect that the respirable silica was 11.0% respirable dust. This JEM has been used in a recent epidemiologic study to assess mortality in Vermont granite workers and to examine the relationships among mortality from silicosis, lung cancer, and other nonmalignant respiratory diseases.

Ground-based off-line aerosol measurements at Praia, Cape Verde, during the Saharan Mineral Dust Experiment: microphysical properties and mineralogy

A large field experiment of the Saharan Mineral Dust Experiment (SAMUM) was performed in Praia, Cape Verde, in January and February 2008. This work reports on the aerosol mass concentrations, size distributions and mineralogical composition of the aerosol arriving at Praia. Three dust periods were recorded during the measurements, divided by transitional periods and embedded in maritime-influenced situations. The total suspended particle mass/PM10/PM2.5 were 250/180/74μg/m3 on average for the first dust period (17–21 January) and 250/230/83μg/m3 for the second (24–26 January). The third period (28 January to 2 February) was the most intensive with 410/340/130 μg/m3. Four modes were identified in the size distribution. The first mode (50–70 nm) and partly the second (700–1100 nm) can be regarded as of marine origin, but some dust contributes to the latter. The third mode (2–4 μm) is dominated by advected dust, while the intermittently occurring fourth mode (15–70 μm) may have a local contribution. The dust consisted of kaolinite (dust/maritime period: 35%wt./25%wt.),K-feldspar (20%wt./25%wt.), illite (14%wt./10%wt.), quartz (11%wt./8%wt.), smectites (6%wt./4%wt.), plagioclase (6%wt./1%wt.), gypsum (4%wt./7%wt.), halite (2%wt./17%wt.) and calcite (2%wt./3%wt.).

The Impact of Yellow Dusts From China on Air Quality in Northern Taiwan From 1994 to 2008

PP-29-035 Background/Aims: Air quality in Taiwan has been improved in recent years, causing significant changes in the yellow dusts from north-west China affecting Taiwan. The objective of this study is to recognize the effect of yellow dust on Taiwan originating from China on a daily basis. Methods: Between 1994 and 2008, the data are derived from hourly particulate matter (PM10) and CO value taken from the monitoring stations located in the city center, northern and eastern coast, and national park. We determine that a day is affected by dust when PM10 concentration increases from both northern and eastern coast, and the National Park monitoring stations simultaneously, and at the same time, the daily average concentration of PM10 from the city center monitoring station records values >125 μg/m3. We also distinguish the Asian dust events by measuring decreasing CO levels during the dust period, and increasing CO levels during periods of locally accumulating pollution. Results: It is estimated that 53 dust events were influenced by yellow dust from China during 1994 to 2008, with the most occurrences during 2000 to 2007 showing an increasing trend, especially during 2000 where occurrences went up to 9. The most frequent times occurred in the months of March and April, totaling at 46%. On average, the concentration of PM10 in dust impact day is 4 times higher than its non-dust impact day. In addition, CO is not accumulated in dust impact day. Conclusion: Taiwan is largely affected by the dust storms from China, even though it is away from the originate area of dust. Increasing PM concentrations in the ambient air causes human health hazards such as respiratory tract and cardiovascular disease. We should enforce our authority to concern this issue and do better in forecast.

An Orchestrated Attempt to Determine the Chemical Properties of Asian Dust Particles by PIXE and XRF Techniques

An orchestrated attempt was made to analyze samples of bulk and individual particulate matters (PM) collected at the Gosan ground-based station on the west coast of Jeju, Korea. A two-stage filter pack sampler was operated to collect particles in both large (＞1.2 ㎛) and small size fractions (＜1.2 ㎛) between the Asian dust (hereafter called “AD”) storm event and non-Asian dust period. Elemental components in bulk and individual particles were determined by PIXE and synchrotron XRF analysis systems, respectively. To assess the transport pathways of air parcels and to determine the spatial distribution of PM, the backward trajectories of the Meteorological Data Explorer (Center for Global Environmental Research, 2010) and the NOAA’s HYSPLIT dispersiontrajectory models were applied. In line with general expectations, Si and other crustal elements in large size particles showed considerably higher mass loading on AD days in comparison with non-AD days. Computation of the crustal enrichment factors [(Z/Si)particle/(Z/Si)desert sand] of elements in large size particles (＞1.2 ㎛) allowed us to estimate the source profile and chemical aging of AD particles as well as to classify the soil-origin elements. On the basis of a single particle analysis, individual AD particles are classified into three distinct groups (neutralized mineral particles, S-rich mineral particles, and imperfectly neutralized particles).