Kosa Aerosol Research Articles

Characteristics of Color and Chemical Composition of Surface Soils Collected in Source Regions of Asian Dusts and Identification of the Source of Kosa Aerosols Transported to Japan

Characteristics of Color and Chemical Composition of Surface Soils Collected in Source Regions of Asian Dusts and Identification of the Source of Kosa Aerosols Transported to Japan

Chemical Characteristics of Significant Kosa Aerosols Observed in Japan

Chemical Characteristics of Significant Kosa Aerosols Observed in Japan

Adverse effects of inhaled sand dust particles on the respiratory organs of sheep and goats exposed to severe sand storms in Mongolia.

Sand storms in Mongolia have increased in frequency and scale, resulting in increased exposure of the inhabitants of Asian countries, including Japan and Korea, to Asian sand dust (ASD), which results in adverse effects on the respiratory system. However, there is no information on the health risks of severe sand storms in domestic animals in Mongolia. The aim of the study was to investigate the effects of sand dust particles on the respiratory organs, including the lungs and tracheobronchial lymph nodes, of sheep and goats exposed to severe sand storms in Mongolia. Seven adult sheep and 4 adult goats that had been exposed to sand storms and 3 sheep with no history of exposure were included in this study. Lung tissues and tracheobronchial lymph nodes were subjected to histopathological and immunohistochemical examination. The mineralogical contents of the lungs and lymph nodes were determined using inductively coupled plasma atomic emission spectroscopy. Fibrosis and granulomatous lesions comprising macrophages containing fine sand dust particles were observed exclusively in the lungs of sheep and goats exposed to sand storms. The activity of macrophages was also demonstrated by the presence of IL-6, TNF, and lysozyme. In addition, silicon, which is the major element of ASD (kosa aerosol), was detected exclusively in the lung tissues of the exposed animals. Our findings suggest that exposure to sand dust particles may affect the respiratory systems of domestic animals during their relatively short life span.

Solubility of Iron in the Aerosol Collected during Kosa (Asian Dust) Events in Japan

The main contributor of aerosol particulate soluble iron to Japan and the Pacific Ocean has been investigated using data obtained during the research campaign entitled “A Study on Dust and Sand Storms” conducted by the Ministry of the Environment, Japan. The concentration of particulate soluble iron was not correlated to total iron concentration. Particulate iron solubility ranged from less than 1% to 6%. It was low when the air mass was dominated by kosa aerosols, and high when the air mass was dominated by pollutants. Durations for the kosa and pollution events over Jeju Island, Matsue, and the Pacific Ocean in April and May 2007 were estimated using a Chemical Weather Forecasting System (CFORS). The estimated durations of the pollution events at Jeju and Matsue were slightly shorter than those of the kosa events. The calculated duration of the pollution event over the Pacific Ocean was only three hours, much shorter than that of the kosa event. Kosa aerosols are the main contributor of soluble iron to the Pacific Ocean; however anthropogenic aerosols should not be discounted as contributors of soluble iron to an area off the coast of the Asian continent.

Analysis for Chemical Characterization of Atmospheric Aerosols Application of X-ray Microprobe System and Double Thin Film Method

The X-ray microprobe system was applied to ultra trace characterization of single Kosa aerosols and non-Kosa aerosols simultaneously collected at Yasaka, Japan and TaeAnn, Korea. We demonstrated remarkable mass increase of heavy metals as well as soil components in individual particles during the Kosa event compared with the non-Kosa period at Yasaka. Backward trajectory analysis suggested that the Kosa samples were in the mixing state of mineral components and anthropogenic heavy elements. Double thin film method was applied to investigate the seasonal change of the mixing states of single sea-salt aerosols associated with chlorine loss due to the heterogeneous reactions between sea-salt particles and acidic gases. It was revealed that the percentages of both chloride-nitrate mixed particles and sulfate-nitrate ones were larger in wintertime than those in summertime and fraction of chloride-nitrate mixed particles increased with an increase of particle size. Comparison between the size-segregated bulk analysis and the single particle analysis demonstrated that remarkable chloride depletion occurred in coarse particles sampled on May in the former analysis, while chloride depletion in coarse particles was not marked in the latter analysis. The discrepancy attributes to the difference of the sampling time between both analyses because significant change of air mass route occurred during the bulk sampling after completion of the single particle sampling.

Investigation of Individual Micrometer-Size Kosa Particle with On-Site Combination of Electron Microscope and Synchrotron X-Ray Microscope

The Kosa (yellow sand) aerosol affects the global environment as well as human health because it migrates from the interior of China to other areas, absorbing various atmospheric elements. Investigation into individual Kosa aerosol particles, which are submicroscopic to several tens of micrometers in diameter, is required to resolving the issue. We installed a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX) on a synchrotron radiation (SR) beam line and introduced the SR beam into the SEM chamber for combinatorial application of SEM-EDX and SR X-ray fluorescence (SR-XRF) spectrometry to individual particles. It should be noted that detailed topographic observation by SEM and sensitive elemental analysis by SR-XRF, both crucial for individual particle measurement but which previously had to be carried out separately, were jointly performed inside the SEM chamber in this setup. Here, we show that SR-XRF results, in conjunction with SEM images, contributed toward resolving individual particle dispositions. Atmospheric sulfur primarily adheres to calcium in the aerosol particles and the particle surface roughens as a consequence of the chemical reaction between the two elements.

Characterization of Individual Silicon‐Poor Particles in Atmospheric Aerosols by SEM‐EDX and Application to Kosa Particle Identification

Silicon‐poor particles, mainly composed of mafic minerals such as olivine or pyroxene, were examined as an indicator of eolian dust particles from China, called the Kosa aerosol in Japan. A method of scanning electron microscopy–energy dispersive x‐ray microanalysis (SEM‐EDX) has been developed to discriminate Kosa‐derived, individual Si‐poor particles from Japanese igneous rock–derived ones. Prior to single‐particle analysis by the SEM‐EDX, atmospheric particle samples were ignited at 1000°C for 6 hr, and thereafter the ignited samples were washed in hydrochloric acid, in order to remove organic matter, soluble‐formed secondary particles, easily‐weathering minerals having medium SiO2 content, and so forth. Particles having a SiO2 content of 30–50% in the residue after the acid treatment were defined as Si‐poor particles in this study, and the elemental composition was determined by SEM‐EDX using a standardless ϕ (ρz) correction. Si‐poor particles are characterized by their high contents of Mg and Fe, so that a correlation plot between MgO/Fe2O3 and MgO/SiO2 was examined for individual Si‐poor particles. Atmospheric aerosol sampling was carried out at the northern foot of Mt. Fuji, central Japan, and the distribution areas under the Kosa phenomena in the correlation plot widely differed from those of background aerosol at the sampling site. Also, the correlation plot showed a clear temporal variation corresponding to transporting episodes of the Kosa aerosol. The variation of major elements like Mg and Fe in Si‐poor particles was wide compared to that of trace impurities (Na and K) in Si‐rich particles like quartz. These results indicate that Si‐poor particles are an indicator that can be used to identify the Kosa‐derived particles grain by grain and to investigate transportation of the Kosa aerosol. This paper was by special invitation as a contribution to a special issue of the journal entitled “Application of Spectroscopic Methods to Environmental Problems”. The special issue was organized by Professor Peter A. Tanner, Professor in the Department of Biology and Chemistry at City University of Hong Kong.

Short-term cycle of eolian dust (Kosa) recorded in Lake Kawaguchi sediments, central Japan

Abstract The fluctuation during the last 100 yr of the eolian dust (Kosa aerosol) originating from arid and semi-arid areas of China has been reconstructed by using the sediments from Lake Kawaguchi, central Japan with high temporal resolution. The quantification of Kosa contribution to the sediments was carried out by a new method using scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EDX) proposed by us. The correlation plot of (Na 2 O+K 2 O) contents against SiO 2 was used for individual Si-rich particles having SiO 2 content over 80%. The Kosa fraction of Si-rich particles in Lake Kawaguchi sediments during the last 100 yr is approximately 10–30%. The fluctuation of the Kosa fraction during the last 100 yr does not coincide with that of the total amount of Si-rich particles, because detrital components from Japanese igneous rocks control the fluctuation of the total number of Si-rich particles. The discrimination method based on single particle analysis is more effective than that of bulk analysis for the lake sediments formed by complex matrix components. We can first show a short-term (approximately 10–20 yr scale) cycle in Kosa aerosol fluctuation. Higher sedimentation rates (5–10 yr-cm) of the Lake Kawaguchi sediments and the new analytical method using SEM-EDX revealed a remarkable fluctuation pattern of Kosa aerosol, suggesting climate cycles much shorter than glacial–interglacial. Such short-term cycles may be related to sun-spots. The number of days of Kosa events during the last 30 yr, obtained by visual observation by Meteorological Agency of Japan, also supports the presence of such a short-term cycle.

Retrieval of Asian Dust Amount over Land using ADEOS-II/GLI near UV Data

We propose a retrieval method of Asian dust (Yellow sand or Kosa aerosol) columnar amount around source regions using a near ultraviolet radiometry observation from space. The method simultaneously retrieves an optical thickness and mode radius of Kosa aerosol, and then derives its columnar amount. The method was applied to ADEOS-II/GLI data in the spring of 2003 around Taklimakan desert source region, inland China. The retrieved optical thickness and mode radius were about 0.34 and 1.75 µm, respectively, at a validation site. They are comparable to the in situ observations conducted within the framework of ADEC project. The estimated columnar amount around a validation site is about 2.77 g m-2, which seems reasonable under a relatively calm situation. The method should be further validated with a regional model simulation study, and then it is useful to monitor Asian dust around source regions from space in the future.

Water Soluble Chemical Components Originated from KOSA Aerosols in Deposits Collected by Bulk Samplers

Water Soluble Chemical Components Originated from KOSA Aerosols in Deposits Collected by Bulk Samplers

Change in size distribution and chemical composition of kosa (Asian dust) aerosol during long-range transport

Abstract Kosa (Asian dust) aerosol was sampled at eight locations in China and Japan along the route of the dust event in March 2001. Mass concentrations, concentrations of the chemical components in the aerosol, and the size distribution of the aerosol were examined. The mass concentration of the aerosol was 6700 μg m−3 in the Chinese interior (in and around the Inner Mongolia Autonomous Region); 1500 μg m−3 at Beijing, China; and 230 μg m−3 at a remote island in Japan. The concentrations dropped by one order of magnitude as the dust was transported from the interior of China to Japan. As with the mass concentrations, the concentrations of crustal elements in the aerosol, e.g., Al, Fe, etc., followed this same trend and decreased by one order of magnitude or more as the dust made its way from the Chinese interior to Japan. Coefficients of determination (r2) were greater than 0.9 for all linear regressions of crustal element concentration on Al concentration in the size-separated coarse particles larger than 2.1 μm in aerodynamic diameter, for samples from both China and Japan. This indicated that the concentrations of all the crustal elements in coarse particles were constant and did not depend on particle size. However, the concentration of NO3− was higher in Japan (e.g., a remote island sampling site: 5.8 μg m−3) than in China (e.g., an inland sampling site: 1.7 μg m−3). Coefficients of determination (r2) were greater than 0.9 for linear regressions of NO3− concentrations on the [Almass/D], where Almass is the Al concentration and D is representative diameter, for size-separated particles larger than 2.1 μm in diameter both in China and Japan. This indicated that NO3− was attached to the surface of the kosa aerosol particles.

Kosa (yellow sand) components in precipitation collected at central Japan

In east Asia, acidic gases derived from fossil fuel combustion have increased in the past decades. On the other hand, the Asian dust, also called Kosa (yellow sand) is transported following windstorms from arid lands in the Asian continent. Many researchers have been interested in the reaction between acidic aerosols and Kosa aerosols as well as the long-range transport of these emissions. To investigate the characteristics of chemical components in precipitation on a long-term basis over Japan, precipitation was sequentially collected from April 1984 to March 1997 at Kanazawa located near the coast of the Sea of Japan. Precipitation samples were collected at 1 mm intervals for the first 5 mm rainfall and all volume of rainwater after 6 mm for all precipitation events with an automatic wet only precipitation collector. According to the analyses of precipitation including Kosa aerosols during Kosa periods, the reaction in the air between Kosa and acidic components during the long-range transport was discussed.

Estimation of the concentration and chemical composition of kosa aerosols at their origin

Kosa aerosols are formed of mineral dust lifted into the atmosphere by dust storms generated over the Asian continent. An intense dust storm which lifted kosa particles into the atmosphere was generated over the Badain Jaran Desert, China from 14 to 15 April 1998. We sampled the kosa aerosol at seven locations in China and Japan along its transport route, and investigated aerosol mass concentrations and the concentrations of chemical components in the aerosol. The aerosol mass concentrations and concentrations of crustal elements in the aerosols decreased exponentially with the distance from the kosa aerosol source. The chemical composition of the kosa aerosol at source, estimated from regressions of aerosol crustal element concentrations on distance from the kosa source, closely coincided with those of simulated Asian mineral dust certified reference material (CJ-2) prepared from the desert surface soil. The estimated concentration of Al in the kosa source aerosol was 5.3×10 3 μg m −3 and the aerosol mass concentration was 9.0×10 4 μg m −3.

Thermochemical characterization of pigeon pea stalk for its efficient utilization as an energy source

The fluctuation during the last 100 yr of the eolian dust (Kosa aerosol) originating from arid and semi-arid areas of China has been reconstructed by using the sediments from Lake Kawaguchi, central Japan with high temporal resolution. The quantification of Kosa contribution to the sediments was carried out by a new method using scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EDX) proposed by us. The correlation plot of (Na2O+K2O) contents against SiO2 was used for individual Si-rich particles having SiO2 content over 80%. The Kosa fraction of Si-rich particles in Lake Kawaguchi sediments during the last 100 yr is approximately 10–30%. The fluctuation of the Kosa fraction during the last 100 yr does not coincide with that of the total amount of Si-rich particles, because detrital components from Japanese igneous rocks control the fluctuation of the total number of Si-rich particles. The discrimination method based on single particle analysis is more effective than that of bulk analysis for the lake sediments formed by complex matrix components. We can first show a short-term (approximately 10–20 yr scale) cycle in Kosa aerosol fluctuation. Higher sedimentation rates (5–10 yr-cm) of the Lake Kawaguchi sediments and the new analytical method using SEM-EDX revealed a remarkable fluctuation pattern of Kosa aerosol, suggesting climate cycles much shorter than glacial–interglacial. Such short-term cycles may be related to sun-spots. The number of days of Kosa events during the last 30 yr, obtained by visual observation by Meteorological Agency of Japan, also supports the presence of such a short-term cycle.

Identification of Individual Si-Rich Particles Derived from Kosa Aerosol by the Alkali Elemental Composition

Abstract A method of scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EDX) has been investigated for the identification of individual Si-rich particles derived from Kosa aerosol. The elemental composition of individual Si-rich particles (α-quartz) having SiO2 content over 80% was determined by SEM-EDX using a standardless φ(ρz) correction program, and the results were normalized to 100% on the basis of oxide composition. The distribution of (Na2O+K2O)/SiO2(%) in individual Si-rich particles from real airborne particulate matters showed a sharp and clear seasonal variation. It was found that the distribution was closer to those in the China loess and desert sand in spring time compared to those of the non-Kosa aerosol, the distribution could be successfully used as an effective indicator. The distribution of (MgO+CaO)/SiO2(%) was also used for discrimination from Si-rich particles in some Japanese volcanic rocks such as Andesites. Individual Si-rich particles derived from Kosa aerosol were clearly discriminated from those derived from the Japanese igneous rocks by the proposed method. These results suggest that the alkali elemental composition of individual Si-rich particles is a useful indicator to identify the Kosa particles and to investigate transportation of the Kosa aerosol.

The Importance of Sr Isotopic Compositions as an Indicator of Acid-Soluble Minerals in Arid Soils in China

Aeolian particles originating from arid areas in China, termed Kosa, are considered to be a major source of non-sea-salt Ca, a dominant base cation, in acid precipitation in northeastern Asia. We extracted evaporite minerals (halite, gypsum, and carbonate) from the surface soil collected at eight desert and loess areas in northern China with water and acetic acid. Most 87Sr/86Sr ratios of the extracted fractions fell in a restricted range (0.7115 ± 0.0015) and differed from those of bulk soils and acid-insoluble minerals (0.712–0.717). The selective dissolution of the soil carbonates in the atmosphere is consistent with two facts: (1) their 87Sr/86Sr ratios are close to the maximum 87Sr/86Sr ratios of spring precipitation in Japan, when Kosa activity is marked; and (2) their mole ratios of Mg/Ca (0.15) and Sr/Ca (0.001) are almost identical to those of precipitation in China and Japan when Kosa activity is marked. The 87Sr/86Sr, Mg/Ca, and Sr/Ca ratios in the acid-soluble components can be used as indexes of Kosa aerosols in the precipitation of the northwestern Pacific.

Chemical characteristics of free tropospheric aerosols over the Japan Sea coast: aircraft-borne measurements

Atmospheric aerosol particulate matter was directly collected in the free troposphere over the Japan Sea coast between 1992 and 1994 using an aircraft-borne nine-stage cascade impactor (particle size range: 0.1–8 μm). The water-soluble components in the aerosol particulate matter were analyzed by ion chromatography. Particulate sulfate and ammonium were detected in most of the samples and their size distributions showed noticeable peaks below the 1 μm particle size range. Water-soluble calcium (Ca 2+) was detected in half of the samples; the size distribution showed that the maximum particle size was larger than 1 μm. Highly concentrated Ca 2+ in larger particles was possibly due to transport of Kosa aerosols from the Asian continent in the free troposphere. The concentration of fine particulate sulfate and ammonium tended to increase whenever Ca 2+ was detected, which suggests possible mixing of Kosa aerosols and non-Kosa aerosols during long-range transport of air masses containing Kosa particles.

Chemical reaction during the coagulation of ammonium sulphate and mineral particles in the atmosphere

Until now the climatic effects of mineral dust in the atmosphere has been limited to a consideration of physical processes. Here we present evidence for a chemical reaction occurring upon the coagulation of an Asian dust ( kosa) aerosol and ammonium sulphate particles in the atmosphere in which the calcium carbonate in the kosa particles reacted with the ammonium sulphate, at a rate measured in days, to yield koktaite [(NH 4) 2Ca(SO 4) 2·H 2O] as an intermediate product and, finally, gypsum (CaSO 4·2H 2O). Koktaite was present in an aerosol sample collected in Beijing, China during a kosa event, but it is absent from the soils from which the kosa aerosol originates. This reaction may have significant climatic consequences.

Indicator elements of Kosa aerosol having alkaline property

Indicator elements of Kosa aerosol having alkaline property

Water Soluble Components in Kosa Aerosols Collected in Korea

Water Soluble Components in Kosa Aerosols Collected in Korea