Asian Dust Storm Period Research Articles

Field observation on secondary organic aerosols during Asian dust storm periods: Formation mechanism of oxalic acid and related compounds on dust surface

Chemical evolution of East Asian dust during transpacific transport has been given much attention for inorganic species such as sulfate, nitrate and ammonium. However, the role of organic species during the transport has almost entirely been ignored. To understand the formation mechanism of secondary organic aerosols (SOA) on dust surfaces, this study investigated the concentrations and compositions of dicarboxylic acids, keto-carboxylic acids, α-dicarbonyls and inorganic ions in size-segregated aerosols (9-stages) collected in Xi'an, central China during the two dust storm episodes in the springs of 2009 and 2011 and compared with those in nondust storm periods. During the events the ambient particulate dicarboxylic acids were 932–2240 ng m−3, which are comparable and even higher than those in nondust periods. Molecular compositions of the above SOA are similar to those in nondust periods with oxalic acid being the leading species. In the presence of the dust storms, all the above mentioned SOA species in Xi'an were predominantly enriched on the coarse particles (>2.1 μm), and oxalic acid well correlated with NO3− (R2 = 0.72, p < 0.001) rather than SO42−. This phenomenon differs greatly from the SOA in any other nondust period that is usually characterized by an enrichment of oxalic acid in fine mode and a strong correlation of oxalic acid with SO42−. We propose a formation pathway to explain these observations, in which nitric acid and/or nitrogen oxides react with dust to produce Ca(NO3)2 and form a liquid phase on the surface of dust aerosols via water vapor-absorption of Ca(NO3)2, followed by a partitioning of the gas-phase water-soluble organic precursors (e.g.,glyoxal and methylglyoxal) into the aqueous-phase and a subsequent oxidation into oxalic acid. To the best of our knowledge, we found for the first time the enrichment of glyoxal and methylglyoxal on dust surface. Our data suggest an important role of nitrate in the heterogeneous formation process of SOA on the surface of dust.

Source Apportionment of Submicron Particle Size Distribution and PM2.5 Composition during an Asian Dust Storm Period in Two Urban Atmospheres

Asian dust storms (ADS), coming from deserts of China and Mongolia, have serious environmental impact on particulate matter (PM) and other pollutants in Taiwan. This study selected two urban sites, Taipei and Kaohsiung, to evaluate the influence of ADS on air quality. During the ADS periods, the hourly PM10 mass concentrations were 800 µg m–3 in Taipei and the 400 µg m–3 in Kaohsiung, which was three to five times higher than PM episodes during the non-ADS periods. By using the principal component analysis (PCA) manner, the potential sources, the dust storm contained, can be successfully identified during ADS periods. The other potential sources can be identified as vehicular emission and secondary organic aerosols from local area. There have been many studies conducted on the impact of ADS on airborne coarse particle concentration, but very few on fine particle concentration. This study focused on, using PCA for analysis and discussion, the impact of ADS on submicron particle size distribution. The results showed that there was no close relationship between the ADS and Aitken mode (30–100 nm or D30–100nm) or accumulation mode (from 0.1–1 µm). However, it was found that strong correlation existed between the ADS and nucleation mode (10–30 nm or D10–30nm). In addition, it was found that nucleation mode appeared first, followed by an air plume of dust particles twelve (12) hours later. The nucleation component from the PCA could be used as predictors of arrival time for an ADS. Taking into account the effects of meteorological conditions and employing technique of backward trajectories, PCA can be utilized as a powerful tool to better identify the source of dust storms and provide accurate results.

Characteristics of atmospheric suspended soil particles in the Asian dust-storm period in Kobe city

Characteristics of atmospheric suspended soil particles in the Asian dust-storm period in Kobe city

Asian Dust Particles Induce TGF-β1via Reactive Oxygen Species in Bronchial Epithelial Cells

BackgroundAsian dust storms can be transported across eastern Asia. In vitro, Asian dust particle-induced inflammation and enhancement of the allergic reaction have been observed. However, the fibrotic effects of Asian dust particles are not clear. Production of transforming growth factor β1 (TGF-β1) and fibronectin were investigated in the bronchial epithelial cells after exposure to Asian dust particulate matter (AD-PM10).MethodsDuring Asian dust storm periods, air samples were collected. The bronchial epithelial cells were exposed to AD-PM10 with and without the antioxidant, N-acetyl-L-cysteine (NAC). Then TGF-β1 and fibronectin were detected by Western blotting. The reactive oxygen species (ROS) was detected by the measurement of dicholorodihydrofluorescin (DCF), using a FACScan, and visualized by a confocal microscopy.ResultsThe expression of TGF-β1, fibronectin and ROS was high after being exposed to AD-PM10, compared to the control. NAC attenuated both TGF-β1 and fibronectin expression in the AD-PM10-exposed the bronchial epithelial cells.ConclusionAD-PM10 may have fibrotic potential in the bronchial epithelial cells and the possible mechanism is AD-PM10-induced intracellular ROS.

제주지역 TSP 이온성분 농도의 장기 변화

The water-soluble components have been analyzed from the total suspended particulate (TSP) collected at Gosan site of Jeju Island for ten years (1997~2006), and the long-term variations of ionic constituent concentrations have been investigated in order to understand the pollution characteristics of atmospheric aerosols. Their mean concentrations were in the order of nss- > > > > > nss- > > . The concentrations had increased somewhat smoothly compared to those of for the past 10 years, possibly indicating the recent energy consumption pattern changes in China. The concentrations of ionic aerosol components showed mostly higher values during the Asian Dust storm periods, and the concentration ratios of nss-, , and nss- between the Asian Dust and Non-Asian Dust periods were 6.9, 2.4, and 1.3, respectively. The anthropogenic nss-, , and the soil originated nss- components showed high concentrations as the air parcels were moved from the Asia continent, on the other hand, their concentrations were relatively low as moving from the Northern Pacific into the Gosan area.

Enhancement of particulate organic carbon export flux induced by atmospheric forcing in the subtropical oligotrophic northwest Pacific Ocean

The effects of extreme atmospheric forcing on the export flux of particulate organic carbon (POC) in the warm oligotrophic nitrogen-limited northwest Pacific Ocean were examined in 2007 during the spring Asian dust storm period. Several strong northeast monsoon events (maximum sustained wind speeds approaching 16.7 m s − 1 , and gusts up to 19.0 m s − 1 ) accompanied by dust storms occurred during a 1-month period. The cold stormy events decreased surface water temperature and induced strong wind-driven vertical mixing of the water column, resulting in nutrient entrainment into the mixed layer from subsurface waters. As a result, the export flux of POC ranged from 49 to 98 (average value = 71 ± 16) mg m − 2 day − 1 , approximately 2–3 times greater than average values in other seasons. As dry and wet deposition of nitrogen attributable to Asian dust storm events does not account for the associated increases in POC stocks in this N-limited oligotrophic oceanic region, the enhancement of POC flux must have been caused by nutrient entrainment from subsurface waters because of the high winds accompanying the dust storm events.

The impact of air quality on respiratory admissions during Asian dust storm periods

The objective of this study was to assess the temporal and spatial patterns of air quality during Asian dust storm (ADS) events between 2000 and 2004, as well as their correlation with the frequency of respiratory admissions in the clinics and hospitals of metropolitan Taipei, Taiwan. The daily air pollutant concentrations and the respiratory admissions on the “index days” were compared with those on the “comparison days”. A Geographical Information System (GIS) was used to map the distributions of the air pollutant concentrations and the respiratory admissions. The results showed that short duration ADS events caused a larger Revised Air Quality Index (RAQI) than the long duration ADS events. PM10 and O3 concentrations significantly increased on the first two days of ADS events. The areas showing significant increases in respiratory admissions did not match well with the areas with the most significant air quality deterioration.

Mineralogical characteristics of airborne particles collected in Beijing during a severe Asian dust storm period in spring 2002

Asian dust storm (ADS) samples were collected on March 20, 2002 in Beijing, China. High-resolution field emission scanning electron microscopy with energy dispersive X-ray detector (FESEM-EDX) and X-ray diffraction (XRD) were used to study the morphology, chemical compositions, number-size distributions and mineralogical compositions of ADS particles. The mineral particles were major components in the ADS samples, accounting for 94% by number. The XRD analysis indicated that the dust particles were dominated by clay (40.3%), and quartz (19.5%), followed by plagioclase (8.4%), calcite (7.5%), K-feldspar (1.5%), hematite (0.9%), pyrite (0.9%), hornblende (0.4%) and gypsum (0.3%), with a certain amount of noncrystalline materials (20.3%). Clay minerals were mainly illite/smectite mixed layers (78%), followed by illite (9%), kaolinite (6%), and chlorite (7%). In addition to these main minerals, FESEM-EDX also detected some trace minerals, such as dolomite, pyrite, thenardite, as well as heavy minerals represented by rutile, ilmenite and apatite. The mineralogical compositions of the 2002-03-20 Asian dust storm and the Saharan dust plumes were similar but the clay mineralogy showed a great distinction, with the illite/smectite mixed layers being common in the Asian dust storm but illite being common in the Saharan dust plumes.

DMS photochemistry during the Asian dust-storm period in the Spring of 2001: model simulations vs. field observations

This study examines the local/regional DMS oxidation chemistry on Jeju Island (33.17°N, 126.10°E) during the Asian dust-storm (ADS) period of April 2001. Three ADS events were observed during the periods of April 10–12, 13–14, and 25–26, respectively. For comparative purposes, a non-Asian-dust-storm (NADS) period was also considered in this study, which represents the entire measurement periods in April except the ADS events. The atmospheric concentrations of DMS and SO 2 were measured at a ground station on Jeju Island, Korea, as part of the ACE-Asia intensive operation. DMS (means of 34–52 pptv) and SO 2 (means of 0.96–1.14 ppbv) levels measured during the ADS period were higher than those (mean of 0.45 ppbv) during the NADS period. The enhanced DMS levels during the ADS period were likely due to the increase in DMS flux under reduced oxidant levels (OH and NO 3). SO 2 levels between the two contrasting periods were affected sensitively by some factors such as air mass origins. The diurnal variation patterns of DMS observed during the two periods were largely different from those seen in the background environment (e.g., the marine boundary layer (MBL)). In contrast to the MBL, the maximum DMS value during the ADS period was seen in the late afternoon at about sunset; this reversed pattern appears to be regulated by certain factors (e.g., enhanced NO 3 oxidation). The sea-to-air fluxes of DMS between the ADS and NADS periods were calculated based on the mass-balance photochemical-modeling approach; their results were clearly distinguished with the values of 4.4 and 2.4 μmole m −2 day −1, respectively. This study confirmed that the contribution of DMS oxidation to observed SO 2 levels on Jeju Island was not significant during our study period regardless of ADS or NADS periods.

Characteristics of particles sampled in southern Taiwan during the Asian dust storm periods in 2000 and 2001

Abstract Intensive field samplings followed by laboratory measurements were performed to characterize the particles collected at urban and rural sites in southern Taiwan during the Asian dust storm (ADS) periods in 2000 and 2001. These particles were size-resolvedly (cut sizes of eight-and ten-stages) sampled by two side-by-side micro-orifice uniform-deposited impactors (MOUDI). Results show that the concentrations of PM2.5, PM2.5–10 and PM10 increased during the ADS periods and these PM10 concentrations, >150 μg m−3, were roughly 2 to 3 times higher than the average PM10 concentrations measured in non-ADS periods. The concentrations of particle-bearing water-soluble ions including four crust-related species (Ca2+, Mg2+, Na+, and K+), three secondary aerosol-associated species (SO42−, NO3−, and NH4+), and one sea-connected species (Cl−) increased and their size distributions changed during the ADS periods in comparison with those during non-ADS periods, implying that they were partially from foreign sources. This supports the increasing health concerns for ADS. The SO42− had a major mode in fine size range (0.56–1.0 μm) while the Ca2+ obtained a major mode in coarse size (3.2–5.6 μm) at both sites.

Aerosol optical and radiative properties observed at Anmyeon and Jeju, Korea in the spring of 2000 and 2001.

The radiative properties of atmospheric aerosols are determined by their masses, chemical characteristics, and optical properties, such as aerosol optical depth (AOD), Angström parameter (alpha) and single scattering albedo (SSA). In particular, the aerosol optical properties determine the surface temperature perturbation that may give some information in understanding regional atmospheric radiative forcing. To understand the radiative forcing and regional source of an aerosol, the present study focused on the analysis of the aerosol optical properties based on two different observations in the spring season, during the special Asian dust storm period. The Korean Global Atmosphere Watch Observatory (KGAWO), at Anmyeon Island, and the ACE-Asia super-site, at Gosan, Jeju Island, have measured radiations and aerosols since 2000. The sites are located in the mid-west and south of the Korean peninsula, which are strongly affected by the Asian dust coming from China every spring. The aerosol optical properties, measured by ground-based sun and sky radiometers, over both sites were analyzed to gain an understanding of the radiation and climate properties. The probability distributions of the aerosol optical depths were rather narrow, with a modal value of approximately 0.38 at both sites during 2001 and 2002. The Angström parameter frequency distributions showed two peaks at Anmyeon GAW, but only one peak at the Jeju ACE-Asia super site. One peak, around 0.63, characterizes the situation of a day having Asian dust, the second peak, around 1.13, corresponded to the relatively dust-free cases. The correlation between the aerosol optical depth and the Angström exponents resulted in a wide range of the Angström parameter, alpha, over a wide range of optical depths at Anmyeon, whereas a narrow range of alpha, with moderate to low values for the AOD at Jeju. Under dust free conditions the single scattering albedo (SSA) decreased with wavelength, while in the presence of Asian dust, the SSA either stayed neutral, or increased slightly with wavelength at Anmyeon, and showed higher value than Jeju. The change in the surface temperature was highly correlated with increases in the aerosol optical depth at Anmyeon to a greater extent than at Jeju.

Mass Concentration and Size-Resolved Chemical Composition of Atmospheric Aerosols Sampled at the Pescadores Islands during Asian Dust Storm Periods in the Years of 2001 and 2002

This study investigated the mass concentration and size distribution of atmospheric aerosols collected at the Pescadores Islands during Asian dust storm periods in the years of 2001 and 2002. As part of an island-wide Asian dust sampling network covering Taiwan and its surrounding islands, an atmospheric aerosol sampling site was established at Xiaumen, Pescadores Islands since March 2001. Xiaumen was at the northwest tip of the Pescadores Islands located at the center of Taiwan Strait and approximately 110 kilometers from the West Coast of the Taiwan Main Island. The sampling protocol was conducted to collect sea level atmospheric aerosols for further physical and chemical analysis. This study revealed that five Asian dust storms invaded the Pescadores Islands during the sampling campaign. The mass concentration of atmospheric aerosols, particularly PM(subscript 2.5-1O), were 2-3 times higher than background levels (i.e., non-Asian dust storm periods). Comparison of hourly PM10 concentration between Xiaumen and ambient air quality monitoring stations in Taiwan indicated that Asian dust storms usually invaded from either the northeast or the northwest and could last for approximately 2 - 4 days. Moreover, Asian dusts could be preliminarily validated in situ by observing the change of their apparent colors from dark gray to light brown. Comparison of hourly PM10 concentration measured at the Pescadores Islands and Taiwan Main Island during the Asian dust storm periods showed that the Asian dust storm invaded Taiwan from either the northwest or the northeast. Increasing both concentration and coarse particle mode in the size distribution of atmospheric aerosols validated the invasion of Asian dust storms. Significant increase of SO4(superscript 2-), Cl(superscript -), Na(superscript +), NH4(superscript +), Mg(superscript 2+) and Ca^(superscript 2+) concentration on coarse particle mode was also observed for Asian dusts. This suggested that not just natural soil dusts but also anthropogenic pollutants and oceanic spray could accompany the Asian dust storms and arrive at the Pescadores Islands.

Quantification on the source/receptor relationship of primary pollutants and secondary aerosols by a Gaussian plume trajectory model: Part III—Asian dust-storm periods

Characteristics of pollutants at heights in the top of the Planetary Boundary Layer (PBL) are collected and used in a local-scale model. A subsidence mechanism is developed to quantify the concentration fraction from the top PBL to simulate PM concentration during Asian dust-storm (ADS) periods. The results show that using the data measured at a mountain station, which is very vulnerable to ADS, as the top boundary conditions for the air quality model can capture all the PM2.5 episodes due to local sources and ADS events, at a low-altitude urban station. The correlation coefficient (r2) of daily PM2.5−10 concentration has increased from 0.17 to 0.62 by incorporating the subsidence mechanism, and that of PM2.5 increases as well. The model results of nitrate, sulfate and ammonium aerosol in fine radii can be compared with observations. According to our analysis, five out of eight PM2.5 or PM10 episode days occurred on ADS days in the past 4 years (1999–2002). During ADS episodes in 2000, 12% of PM2.5 and 53% of PM2.5−10 were from ADS dust. In addition, two dry deposition algorithms are evaluated; the algorithm of Seinfeld and Pandis (Atmospheric Chemistry and Physics from Air Pollution to Climate Change, Wiley, New York, 1998, 1057pp.) is suggested in this case study.

Characteristics of single particles sampled in Japan during the Asian dust–storm period

To investigate the characteristics of Asian dust storm particles as single particles in Japan, we measured morphology, composition and concentration of single particles using Scanning Electron Microscope (SEM) coupled with an energy dispersive X-ray microanalyzer (EDX), particle induced X-ray emission (PIXE) and micro-PIXE. Particles were sampled in Kyoto, Japan from the middle of April to the end of July 1999. Mass concentration in Asian dust–storm events was roughly 3–5 times higher than that of the highest concentration measured in non-Asian dust storm seasons. Single particles were generally sharp-edged and irregular in shape and contained mostly crustal elements such as Si, Fe, Ca and Al. Particles which have more than 40% Si content comprised nearly 50% of coarse single particles in Asian dust storm events. Main concentration range of Al in single Asian dust storm particles was 10–20%, and those of Ca and Fe were below 10%. Even though S and Cl in soils of the desert and loess areas in northwest of China were not detected, significant concentration of S and Cl in coarse fraction in Asian dust storm event were detected in single particles. Especially, the maximum concentration of S in Asian dust storm event was about 5 times higher than that in non-Asian dust storm days. Every single particle in coarse fraction existed as the mixing state of soil components and S. Good agreement between the results of SEM–EDX analysis and that of micro-PIXE analysis was obtained in this study.