non-Asian Dust Research Articles

Extreme Aerosol Events at Mesa Verde, Colorado: Implications for Air Quality Management

A significant concern for public health and visibility is airborne particulate matter, especially during extreme events. Of most relevance for health, air quality, and climate is the role of fine aerosol particles, specifically particulate matter with aerodynamic diameters less than or equal to 2.5 micrometers (PM2.5). The purpose of this study was to examine PM2.5 extreme events between 1989 and 2018 at Mesa Verde, Colorado using Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring data. Extreme events were identified as those with PM2.5 on a given day exceeding the 90th percentile value for that given month. We examine the weekly, monthly, and interannual trends in the number of extreme events at Mesa Verde, in addition to identifying the sources of the extreme events with the aid of the Navy Aerosol Analysis and Prediction (NAAPS) aerosol model. Four sources were used in the classification scheme: Asian dust, non-Asian dust, smoke, and “other”. Our results show that extreme PM2.5 events in the spring are driven mostly by the dust categories, whereas summertime events are influenced largely by smoke. The colder winter months have more influence from “other” sources that are thought to be largely anthropogenic in nature. No weekly cycle was observed for the number of events due to each source; however, interannual analysis shows that the relative amount of dust and smoke events compared to “other” events have increased in the last decade, especially smoke since 2008. The results of this work indicate that, to minimize and mitigate the effects of extreme PM2.5 events in the southwestern Colorado area, it is important to focus mainly on smoke and dust forecasting in the spring and summer months. Wintertime extreme events may be easier to regulate as they derive more from anthropogenic pollutants accumulating in shallow boundary layers in stagnant conditions.

Causes of High PM<sub>2.5</sub> Concentrations in Cheongju Owing to Non-Asian Dust Events

Causes of High PM<sub>2.5</sub> Concentrations in Cheongju Owing to Non-Asian Dust Events

Health Effects of Asian Dust: A Systematic Review and Meta-Analysis.

Background:Potential adverse health effects of Asian dust exposure have been reported, but systematic reviews and quantitative syntheses are lacking.Objective:We reviewed epidemiologic studies that assessed the risk of mortality, hospital admissions, and symptoms/dysfunction associated with exposure to Asian dust.Methods:We performed a systematic search of PubMed and Web of Science to identify studies that reported the association between Asian dust exposure and human health outcomes. We conducted separate meta-analyses using a random-effects model for mortality and hospital admissions for a specific health outcome and assessed pooled estimates for each lag when at least three studies were available for a specific lag.Results:We identified 89 studies that met our inclusion criteria for the systematic review, and 21 studies were included in the meta-analysis. The pooled estimates (percentage changes) of mortality from circulatory and respiratory causes for Asian dust days vs. non-Asian dust days were 2.33% [95% confidence interval (CI): 0.76, 3.93] increase at lag 0 and 3.99% (95% CI: 0.08, 8.06) increase at lag 3, respectively. The increased risk for hospital admissions for respiratory disease, asthma, and pneumonia peaked at lag 3 by 8.85% (95% CI: 0.80, 17.55), 14.55% (95% CI: 6.74, 22.94), and 8.51% (95% CI: 2.89, 14.44), respectively. Seven of 12 studies reported reduced peak expiratory flow, and 16 of 21 studies reported increased respiratory symptoms associated with Asian dust exposure. There were substantial variations between the studies in definitions of Asian dust, study designs, model specifications, and confounder controls.Discussion:We found evidence of increased mortality and hospital admissions for circulatory and respiratory events. However, the number of studies included in the meta-analysis was not large and further evidences are merited to strengthen our conclusions. Standardized protocols for epidemiological studies would facilitate interstudy comparisons. https://doi.org/10.1289/EHP5312

Effects of Asian dust events on atmospheric bacterial communities at different distances downwind of the source region

Aeolian dust particles arising from arid and semiarid zones are known to carry microbes by air currents. The effect of wind-borne bacteria on atmospheric bacterial population at various downwind distances from the dust source regions must be clarified, but has not yet been reported. This study monitored the bacterial abundance and community composition in outdoor aerosol samples in Beijing, China, which is close to the Asian dust source regions, and compared them with the results obtained in a distant region (Osaka, Japan). The Asian dust collected in Beijing contained (4±3)×104bacterial cells/m3, approximately 4 times higher than in Osaka. On 15 April 2015, Beijing experienced severe Asian dust events with a 1000-fold increase in bacterial abundance, relative to non-Asian dust days. Dominant bacterial phyla and classes in Asian dust collected in Beijing were Actinobacteria, Bacilli and Acidobacteria, and the bacterial community composition varied more widely than in Osaka. The bacterial community compositions differed between the Beijing and Osaka dusts, even for the same Asian dust events. These results indicated that aerosol bacterial communities nearer the dust source are more affected by eolian dust than their distant counterparts.

Detection of Pathogenic Viruses in the Ambient Air in Seoul, Korea.

The possible transport of pathogenic microorganisms during Asian dust events could be an important concern for health workers; however, this is still uncertain owing to a lack of supporting evidence. The present study aimed to investigate the presence of pathogenic microorganisms in air samples collected during the Asian and non-Asian dust periods. Between March and September 2016, air samples were collected at three weather observation stations in Seoul using a high-volume air sampler. Multiplex PCR was performed using the Allplex™ respiratory and gastrointestinal panel assay kits to detect 46 microorganisms. RT-PCR was performed for klassevirus, Aichivirus, and human parechovirus (HPeV) detection. In total, 71 air samples were collected during the Asian (8 samples) and non-Asian (63 samples) dust events. During an Asian dust event, only one human rhinovirus (HRV)-positive air sample was collected on April 23. During the non-Asian dust period, HRV, HPeV, norovirus (NoV), enteroaggregative Escherichia coli (EAEC), enterotoxigenic E. coli (ETEC), and Blastocystis hominis were detected in four, two, one, one, one, and one air samples, respectively. Pathogenic viruses were mostly detected in ambient air samples during the non-Asian dust period, which suggests a possible air-borne transmission of viral pathogens; however, the role of Asian dust in epidemics caused by pathogenic viruses is unclear.

Enrichment and geochemical mobility of heavy metals in bottom sediment of the Hoedong reservoir, Korea and their source apportionment

Physicochemical characteristics of bottom sediment in the Hoedong reservoir were studied to evaluate the effectiveness of the reservoir as traps for trace metals. Roadside soil, stream sediment and background soil were also studied for comparison. Sequential extractions were carried out, and lead isotopic compositions of each extraction were determined to apportion Pb sources. Besides, particle size distribution of roadside soil, and metal concentrations and Pb isotopes of each size group were determined to characterize metal contamination. In result, Zn and Cu were enriched in sediment through roadside soil. The data on metal partitioning implied that Zn posed potential hazards for water quality. Meanwhile, the noticeable reduction of the 206Pb/207Pb isotopic ratio in the acid-soluble fraction in the size group 200 μm - 2 mm of national roadside soil indicated that this size group was highly contaminated by automotive emission with precipitation of acid-soluble secondary minerals during evaporation. Based on the Pb isotopic ratios, the dry deposition of Asian dust (AD) and non-Asian dust (NAD) affected roadside soil, while the effects of AD and NAD on bottom sediment appeared to be low given the low metal concentrations in sediment. Metal concentrations and Pb isotopic compositions indicated that sediments were a mixture of background and roadside soil. Source apportionment calculations showed that the average proportion of traffic Pb in bottom and stream sediments was respectively 34 and 31% in non-residual fractions, and 26 and 28% in residual fraction. The residual fraction of sediments appeared to be as contaminated as the non-residual fractions.

Metagenomic Analysis of Airborne Bacterial Community and Diversity in Seoul, Korea, during December 2014, Asian Dust Event.

Asian dust or yellow sand events in East Asia are a major issue of environmental contamination and human health, causing increasing concern. A high amount of dust particles, especially called as particulate matter 10 (PM10), is transported by the wind from the arid and semi-arid tracks to the Korean peninsula, bringing a bacterial population that alters the terrestrial and atmospheric microbial communities. In this study, we aimed to explore the bacterial populations of Asian dust samples collected during November–December 2014. The dust samples were collected using the impinger method, and the hypervariable regions of the 16S rRNA gene were amplified using PCR followed by pyrosequencing. Analysis of the sequencing data were performed using Mothur software. The data showed that the number of operational taxonomic units and diversity index during Asian dust events were higher than those during non-Asian dust events. At the phylum level, the proportions of Proteobacteria, Actinobacteria, and Firmicutes were different between Asian dust and non-Asian dust samples. At the genus level, the proportions of the genus Bacillus (6.9%), Arthrobacter (3.6%), Blastocatella (2%), Planomicrobium (1.4%) were increased during Asian dust compared to those in non-Asian dust samples. This study showed that the significant relationship between bacterial populations of Asian dust samples and non-Asian dust samples in Korea, which could significantly affect the microbial population in the environment.

부유분진측정기(PM10) 관측 자료 실시간 품질관리 알고리즘 개발 및 평가

A real-time quality control algorithm for <TEX>$PM_{10}$</TEX> concentration measured by Continuous Ambient Particulate Monitor (FH62C14, Thermo Fisher Scientific Inc.) has been developed. The quality control algorithm for <TEX>$PM_{10}$</TEX> data consists of five main procedures. The first step is valid value check. The values should be within the acceptable range limit. Upper (<TEX>$5,000{\mu}g\;m^{-3}$</TEX>) and lower (<TEX>$0{\mu}g\;m^{-3}$</TEX>) values of instrument detectable limit have to be eliminated as being unrealistic. The second step is valid error check. Whenever unusual condition occurs, the instrument will save error code. Value having an error code is eliminated. The third step is persistence check. This step checks on a minimum required variability of data during a certain period. If the <TEX>$PM_{10}$</TEX> data do not vary over the past 60 minutes by more than the specific limit (<TEX>$0{\mu}g\;m^{-3}$</TEX>) then the current 5-minute value fails the check. The fourth step is time continuity check, which is checked to eliminate gross outlier. The last step is spike check. The spikes in the time series are checked. The outlier detection is based on the double-difference time series, using the median. Flags indicating normal and abnormal are added to the raw data after quality control procedure. The quality control algorithm is applied to <TEX>$PM_{10}$</TEX> data for Asian dust and non-Asian dust case at Seoul site and dataset for the period 2013~2014 at 26 sites in Korea.

Alterations in the airborne bacterial community during Asian dust events occurring between February and March 2015 in South Korea.

During Asian dust events, a relatively high concentration of particulate matter is transported by wind from arid and semi-arid regions, such as the Gobi and Taklamakan deserts, to nearby countries, including China, Korea, and Japan. The dust particles contain various microorganisms, which can affect human health as well as the environmental microbe population. In the current study, we investigated the characteristics of the airborne bacterial community during Asian dust events between February and March 2015 in South Korea. Bacterial diversity indexes such as operational taxonomic units, Chao1 and Inverse Simpson index were increased, along with total 16S rRNA gene copy number during Asian dust events. The bacterial community structure during Asian dust events was clearly distinguishable from that during non-Asian dust days. The genera Bacillus and Modestobacter were increased 3.9- and 2.7-fold, respectively, while Escherichia-Shigella was decreased by 89.8%. A non-metric multidimensional scaling plot with metadata analysis revealed association of particulate matter concentration, but not temperature, humidity or wind speed, with bacterial community structure, suggesting that the newly transported dust particles contain various microorganisms that influence the airborne bacterial environment.

Investigation of bacterial effects of Asian dust events through comparison with seasonal variability in outdoor airborne bacterial community.

Atmospheric bacterial dispersion with aeolian dust has been reported to have a potential impact on public health and ecosystems. Asian dust is a major aeolian event that results in an estimated 4 million tons of Asian dust particles falling in Japan annually, 3,000–5,000 km away from their source regions. However, most studies have only investigated the effects of Asian dust during dust seasons. Therefore, in this study, outdoor bacterial abundance and community composition were determined by 16S rRNA quantitative PCR and amplicon sequencing, respectively, and compared on Asian and non-Asian dust days (2013–2015; 44 samples over four seasons). Seasonal variations in bacterial abundance of non-Asian dust days were not observed. Bacterial abundance of individual samples collected on non-Asian dust days changed dynamically relative to Asian dust days, with bacterial abundance occasionally reaching those of Asian dust days. The bacterial community composition on non-Asian dust days was rather stable seasonally, and did not differ from that on Asian dust days. These results indicate that bacteria in Asian dust does not immediately influence indigenous bacterial communities at the phylum/class level in distant downwind areas; accordingly, further studies of bacterial communities in downwind areas closer to the dust source are warranted.

Satellite-measured atmospheric aerosol content in Korea: anthropogenic signals from decadal records

Spatiotemporal characteristics and anthropogenic signals of aerosol optical thickness (AOT) distributions over Korea are investigated in this study using AOT time-series data from the Moderate Resolution Imaging Spectroradiometer (MODIS). AOT observations, a quantitative measure of the atmospheric quality, had significant geographical variations during the study period (2000–2010). Comparing metro cities or counties with similar populations, western regions showed higher AOT values than eastern regions. Particular matter with a diameter < 10 µm (PM10), including aeolian dust or yellow dust, is the primary component of atmospheric aerosols, and their transport into the region has shown a strong seasonal pattern with its peak from March to April and lows from July to September. These seasonal dust patterns, however, did not correspond well to temporal AOT records, which typically reached the maximum level in June nationwide. Rather, widespread regional fire events and humidity showed significant correlations with AOT time-series. This correlation rapidly increased as the range of fire occurrence was extended to the west as far as 115°E. The relative humidity also had a significant correlation with AOT during the month of June. In addition to urban emission of anthropogenic aerosols, regional biomass burning and secondary growth of hygroscopic aerosols are considered important contributors to the degradation of the atmospheric environment during the non-Asian Dust season over the Korean Peninsula.

Influences of Long‐Range Transported Air Pollutants on Atmospheric TSP Aerosol Compositions at Jeju Island of Korea during 2011–2013

Atmospheric total suspended particulate aerosols were collected at the Gosan site of Jeju Island during 2011–2013, and their major water‐soluble ionic and elemental species were analyzed in order to examine the chemical composition change and pollution characteristics change between Asian dust (AD) and non‐Asian dust (NAD) periods. The comparison of the aerosol compositions showed that the concentrations of soil‐originated species such as nss‐Ca2+, Al, Fe, Ti, Mn, Ba, and Sr increased by as much as 4.5–18.6 times during the AD periods. Meanwhile, the concentrations of nss‐SO4 2 − and NO3 −, typical secondary aerosol species, increased 1.2 and 2.5 times, respectively. On the contrary, NH4 + concentration decreased slightly during the AD periods, probably because of the neutralization reaction of acidic ammonium ion with basic calcium carbonate. A comparison of ion balances suggested that the carbonate contents in AD are likely much larger than those of NAD. Based on a cluster back‐trajectory analysis, it was found that the concentrations of anthropogenic and soil‐sourced components, such as nss‐SO4 2 −, NO3 −, NH4 +, and nss‐Ca2+, increased when an air mass moved into Jeju Island from the China continent, but decreased when an air mass moved from the North Pacific Ocean.

Size distribution and sources of humic-like substances in particulate matter at an urban site during winter.

This study investigates the size distribution and possible sources of humic-like substances (HULIS) in ambient aerosol particles collected at an urban site in Gwangju, Korea during the winter of 2015. A total of 10 sets of size-segregated aerosol samples were collected using a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI), and the samples were analyzed to determine the mass as well as the presence of ionic species (Na(+), NH4(+), K(+), Ca(2+), Mg(2+), Cl(-), NO3(-), and SO4(2-)), water-soluble organic carbon (WSOC) and HULIS. The separation and quantification of the size-resolved HULIS components from the MOUDI samples was accomplished using a Hydrophilic-Lipophilic Balanced (HLB) solid phase extraction method and a total organic carbon analyzer, respectively. The entire sampling period was divided into two periods: non-Asian dust (NAD) and Asian dust (AD) periods. The contributions of water-soluble organic mass (WSOM = 1.9 × WSOC) and HULIS (=1.9 × HULIS-C) to fine particles (PM1.8) were approximately two times higher in the NAD samples (23.2 and 8.0%) than in the AD samples (12.8 and 4.2%). However, the HULIS-C/WSOC ratio in PM1.8 showed little difference between the NAD (0.35 ± 0.07) and AD (0.35 ± 0.05) samples. The HULIS exhibited a uni-modal size distribution (@0.55 μm) during NAD and a bimodal distribution (@0.32 and 1.8 μm) during AD, which was quite similar to the mass size distributions of particulate matter, WSOC, NO3(-), SO4(2-), and NH4(+) in both the NAD and AD samples. The size distribution characteristics and the results of the correlation analyses indicate that the sources of HULIS varied according to the particle size. In the fine mode (≤1.8 μm), the HULIS composition during the NAD period was strongly associated with secondary organic aerosol (SOA) formation processes similar to those of secondary ionic species (cloud processing and/or heterogeneous reactions) and primary emissions during the biomass burning period, and during the AD period, it was only associated with SOA formation. In the coarse mode (3.1-10 μm), it was difficult to identify the HULIS sources during the NAD period, and during the AD period, the HULIS was most likely associated with soil-related particles [Ca(NO3]2 and CaSO4) and/or sea-salt particles (NaNO3 and Na2SO4).

Using the PIXE method to evaluate the characteristics of aerosols in Kumamoto City, Southwestern Japan, from March 2004 to March 2007

Recently, atmospheric particles, including Asian dust, have attracted considerable attention because of their potential effects on the environment and human health. From March to May, a huge volume of Asian dust is whipped up over China and carried to Japan by the westerly winds. In this study, we analyzed the elemental compositions of 72 aerosol samples collected biweekly in Kumamoto City from March 2004 to March 2007, to investigate the characteristics of Asian dust. The mass concentrations of the aerosol in Asian dust events were 1.5 times higher than non-Asian dust events. The concentrations of elements were determined by the Proton Induced X-ray Emission (PIXE) method. Concentrations of Si, Al, Fe, Ca, Ti, Mg and K in Asian dust events were 2.3, 2.0, 2.0, 1.6, 1.6, 1.5 and 1.4 times higher than those in non-Asian dust events, respectively. These elements are considered indicators of a soil-derived fraction. The concentrations of the soil-derived fraction were calculated, assuming that the Al concentration in the soils is 7%. The predicted mean concentration of the soil-derived fraction in Asian dust events (16.92 μg·m−3) was twice that in non-Asian dust events (8.39 μg·m−3). Moreover, in Asian dust events, the soil-derived fraction was the main component in aerosols and accounted for 43% of the total aerosol mass.

Frequency and Character of Extreme Aerosol Events in the Southwestern United States: A Case Study Analysis in Arizona.

This study uses more than a decade’s worth of data across Arizona to characterize the spatiotemporal distribution, frequency, and source of extreme aerosol events, defined as when the concentration of a species on a particular day exceeds that of the average plus two standard deviations for that given month. Depending on which of eight sites studied, between 5% and 7% of the total days exhibited an extreme aerosol event due to either extreme levels of PM10, PM2.5, and/or fine soil. Grand Canyon exhibited the most extreme event days (120, i.e., 7% of its total days). Fine soil is the pollutant type that most frequently impacted multiple sites at once at an extreme level. PM10, PM2.5, fine soil, non-Asian dust, and Elemental Carbon extreme events occurred most frequently in August. Nearly all Asian dust extreme events occurred between March and June. Extreme Elemental Carbon events have decreased as a function of time with statistical significance, while other pollutant categories did not show any significant change. Extreme events were most frequent for the various pollutant categories on either Wednesday or Thursday, but there was no statistically significant difference in the number of events on any particular day or on weekends versus weekdays.

Lead isotopes combined with a sequential extraction procedure for source apportionment in the dry deposition of Asian dust and non-Asian dust

Lead isotopic compositions were determined in leachates that were generated using sequential extractions of dry deposition samples of Asian dust (AD) and non-Asian dust (NAD) and Chinese desert soils, and used to apportion Pb sources. Results showed significant differences in 206Pb/207Pb and 206Pb/204Pb isotopic compositions in non-residual fractions between the dry deposition samples and the Chinese desert soils while 206Pb/207Pb and 206Pb/204Pb isotopic compositions in residual fraction of the dry deposition of AD and NAD were similar to the mean 206Pb/207Pb and 206Pb/204Pb in residual fraction of the Alashan Plateau soil. These results indicate that the geogenic materials of the dry deposition of AD and NAD were largely influenced by the Alashan Plateau soil, while the secondary sources of the dry deposition were different from those of the Chinese desert soils. In particular, the lead isotopic compositions in non-residual fractions of the dry deposition were homogenous, which implies that the non-residual four fractions (F1 to F4) shared the primary anthropogenic origin. 206Pb/207Pb values and the predominant wind directions in the study area suggested that airborne particulates of heavily industrialized Chinese cities were one of the main Pb sources. Source apportionment calculations showed that the average proportion of anthropogenic Pb in the dry deposition of AD and NAD was 87% and 95% respectively in total Pb extraction, 92% and 97% in non-residual fractions, 15% and 49% in residual fraction. Approximately 81% and 80% of the anthropogenic Pb was contributed by coal combustion in China in the dry deposition of AD and NAD respectively while the remainder was derived from industrial Pb contamination. The research result proposes that sequential extractions with Pb isotope analysis are a useful tool for the discrimination of anthropogenic and geogenic origins in highly contaminated AD and NAD.

Seasonal variation in trace element concentrations and Pb isotopic composition of airborne particulates during Asian dust and non-Asian dust periods in Daejeon, Korea

Trace element contamination (As, Cd, Cr, Co, Cu, Mo, Ni, Pb, S, Zn, and Zr) in both Asian dust (AD) and non-Asian dust (NAD) periods taken from Daejeon, Korea, in 2008 was examined, and the pollution sources were evaluated based on the Pb stable isotope. Additionally, temporal variation in the trace element concentrations of total suspended particulate matter, PM10 and PM2.5, was evaluated in 14 samples for AD and 46 samples for NAD collected from March 2007 to November 2008. Patterns showed that the monthly mean concentrations of trace elements in winter were 2–13 times higher than those in other seasons. In contrast, the monthly mean concentrations of sulfur were the highest in the summer monsoon season. Distinct temporal patterns were observed in the monthly mean concentrations of trace elements, due mainly to high coal combustion in China. These results were supported by the 206Pb/207Pb ratios of AD and NAD, which were identical or similar to those of the airborne particles in certain heavily industrialized Chinese cities and coal and coal combustion dust of China. The Pb isotopic composition in the particulate matter of NAD showed lower 206Pb/207Pb, 207Pb/204Pb, and 206Pb/204Pb ratios in the autumn, winter, and spring seasons, showing the influence of Pb from the heavily industrial cities of China, and higher values in the summer, indicating the dilution and/or mixing effect of the marine air mass from the south.

Assessment of mobility and bio-availability of heavy metals in dry depositions of Asian dust and implications for environmental risk

We assess the potential mobility and bio-availability of selected metals (As, Cd, Co, Cr, Cu, Ni, Mo, Pb, S, Zn, and Zr) in the dry depositions of Asian and non-Asian dust from the city of Daejeon, Korea. For this study, we applied Pb isotopes, total extraction and chemical sequential extraction methods to the dry depositions. In addition, microscopic analysis was performed using X-ray diffraction (XRD) and focused ion beam (FIB)-scanning electron microscopy (SEM-EDS). FIB–SEM cross-section observations and Pb isotope data showed a black carbon is an important carrier of associated heavy metals originating from China. A five-step sequential extraction performed on the dry depositions showed that S and Cd are the most abundant elements in the water-soluble and cation-exchangeable fraction. In addition, Zn and Pb appeared predominantly in the carbonate and reducible fractions. On the other hand, Cu, Mo and, to a lesser degree, As were significantly associated with the organic fraction, while Co, Ni, Cr and Zr were bound to the residual fraction. These results showed that S, Cd, Zn and Pb, which were highly concentrated in potentially mobile fractions, have potential environmental risk because potential changes in redox state and pH may remobilize these metals. In addition, the estimated remobilization concentrations of these metals were significant. Thus, this study shows that frequent and careful monitoring of S, Cd, Z, Pb and, to a lesser degree, Cu, Mo and As is very important for assessing environmental risk in Korea.

부산지역 PM10과 PM2.5중의 금속 농도와 이온농도 특성

Abstract This study analyzes the chemical composition of metallic elements and water-soluble ions in PM 10 and PM 2.5. PM 10 and PM 2.5 concentrations in Busan during 2010-2012 were 97.2±67.5 and 67.5±32.8 ㎍ / ㎥ , respectively, and the mean PM 2.5 /PM 10 concentration ratio was 0.73. The contribution rate of water-soluble ions to PM 10 ranged from 29.0% to 58.6%(a mean of 38.6%) and that to PM 2.5 ranged from 33.9% to 58.4%(a mean of 43.1%). The contribution rate of sea salt to PM 10 was 13.9% for 2011 and 9.7% for 2012, while that to PM 2.5 was 17.4% for 2011 and 10.1% for 2012. PM 10 concentration during Asian dust events was 334.3 ㎍ / ㎥ and 113.3 ㎍ / ㎥ during non-Asian dust events, and the PM 10 concentration ratio of Asian Dust/Non Asian dust was 2.95. On the other hand, the PM 2.5 concentration in Asian dust was 157.4 ㎍ / ㎥ and 83.2 ㎍ / ㎥ in Non Asian dust, and the PM 2.5 concentration ratio of Asian Dust/Non Asian dust was 1.89, which was lower than that of PM 10 . Key words :PM

2008년 대전지역에서 발생한 황사의 중금속 오염도

ABSTRACT The aims of this study were to determine concentrations of selected metals in Asian and non-Asian dust collected inDaejeon, Korea between February 2008 and December 2008 and to estimate the pollution level. The geochemical analysesof Asian dust (AD) and Non Asian dust (NAD) show that the mean concentrations of As, Cd, Cu, Pb, Zn, Zr, Sb, Mo andS reached levels up to 16, 209, 31, 43, 81, 28, 31, 122 and 302 times higher, respectively, than those in uncontaminatedChinese desert soils. These results indicate that both AD and NAD serve as an atmospheric repository for trace and heavy-metal accumulation. The the enrichment factor (EF) and pollution index (PI) show that AD and NAD were severelycontaminated by S, Mo, Zr, Cd, Pb, Zn, Sb, Cu, and As. All indices for these metals showed either strong or notably highlevel of pollution relative to Chinese desert soil, principally due to the severe atmospheric pollution derived fromanthropogenic activities in heavily industrial Chinese cities. Therefore, Mo, Cd, Zr, As, Cu, Sb, Pb, and Zn are the onesmost strongly affected by anthropogenic inputs such as airborne pollutants. Key works : Asian dust, Trace element, Enrichment factor, Pollution index, Pollution level