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| 1.
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Zhang, Daizhou ; Iwasaka, Yasunobu
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Atmospheric particles were collected in southwestern Japan during dust storm events in spring 2000, and the samples were treated with water-dialysis. In this study, size change of dust particles before and after dialysis is discussed with
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respect to their sea salt and sulfur contents. It is confirmed that size increase of dust particles has a strong correlation with their sea salt content but is independent from their non-sea-salt sulfur content. This suggests that the growth of dust particles in size during their dispersion in the marine atmosphere is dominated by the combination with sea salt rather than by other processes such as surface uptake of sulfate.
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| 2.
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Tobo, Yutaka ; Zhang, Daizhou ; Nakata, Naonobu ; Yamada, Maromu ; Ogata, Hiroko ; Hara, Kazutaka ; Iwasaka, Yasunobu
概要:
Morphology and elemental compositions of individual dust particles were investigated with the use of Asian dust samples collected at a site along the Sea of Japan side of the archipelago. Our results indicate the preferential
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formation of chloride in Ca-containing dust particles (0.1 < Cl/Ca < 0.65) in cases when the particles contain little or no sulfate. Most of them are in an amorphous state and nearly spherical even under high vacuum. A likely explanation for the results is that highly soluble salts such as calcium chloride (CaCl2) are formed as a result of heterogeneous reactions of dust particles with chloride precursor gases (mostly, HCl) in the marine atmosphere. The chloride formation is expected to play an important role in enhancing the hygroscopicity of dust particles. Copyright 2009 by the American Geophysical Union.
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| 3.
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Iwasaka, Yasunobu ; Shi, G.-Y. ; Yamada, M. ; Kobayashi, F. ; Kakikawa, Makiko ; Maki, T. ; Naganuma, Takeshi ; Chen, B. ; Tobo, Yutaka ; Hong, C.S.
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金沢大学フロンティアサイエンス機構<br />Long-range transport of atmospheric microbiota with Asian dust (Kosa) particles is of great conce
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rn in Northeast Asia in view of the health effect of Kosa particles on human being, disturbance of ecosystems caused through invasion of new microbe, contribution of microorganisms to biogeochemical cycle on global/regional scales, and others. Information on atmospheric microbes over the desert areas has been desired for a long time. Detection of atmospheric microbiota on the desert regions, on the base of balloon-borne measurements, has been made at Dunhuang, China (40°00′ N, 94°30′ E; east end of Taklamakan desert) in the summer of 2007. The measurements showed that microbiota mixed internally with Kosa particles were frequently floating from the ground to about 2-km heights (above sea level), and possible long-range transport of atmospheric microbiota with dust particles taking local circulations is strongly suggested, causing active mixing of atmospheric dust over the Taklamakan desert from the ground to the free troposphere where westerly jet dominates (Iwasaka et al. in J Geophys Res 108:8652, 2003a, J Geophys Res 108:8644, b). The concentration of the mixed particles of Kosa and microbiota having a size larger than about 1 μm in diameter is estimated to be about 1 particle/cm3 at those heights on the basis of measurements of particle concentration with an optical particle counter and analysis of particles having fluorescence light due to dye of DAPI (4′6-diamidino-2 phenylindole) with an epifluorescence microscope. The mixing situation of microbiota and Kosa particles is the important factor controlling atmospheric lifetime of floating microbiota, since the mixing state certainly can protect microbiota from stressful environments [dryness, solar ultraviolet (UV) radiation, low temperature] in the atmosphere, and therefore, it is useful to discuss the data of the first description of microbiota in the atmosphere on the Taklamakan desert. © 2009 Springer Science+Business Media B.V.
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| 4.
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Tobo, Yutaka ; Zhang, Daizhou ; Matsuki, Atsushi ; Iwasaka, Yasunobu
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金沢大学フロンティアサイエンス機構<br />The chemical history of dust particles in the atmosphere is crucial for assessing their impact on
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both the Earth's climate and ecosystem. So far, a number of studies have shown that, in the vicinity of strong anthropogenic emission sources, Ca-rich dust particles can be converted into aqueous droplets mainly by the reaction with gaseous HNO3 to form Ca(NO 3)2. Here we show that other similar processes have the potential to be activated under typical remote marine atmospheric conditions. Based on field measurements at several sites in East Asia and thermodynamic predictions, we examined the possibility for the formation of two highly soluble calcium salts, Ca(NO3)2 and CaCl2, which can deliquesce at low relative humidity. According to the results, the conversion of insoluble CaCO3 to Ca(NO3)2 tends to be dominated over urban and industrialized areas of the Asian continent, where the concentrations of HNO3 exceed those of HCl ([HNO3/HCl] > ∼1). In this regime, CaCl2 is hardly detected from dust particles. However, the generation of CaCl2 becomes detectable around the Japan Islands, where the concentrations of HCl are much higher than those of HNO3 ([HNO3/HCl] > ∼0.3). We suggest that elevated concentrations of HCl in the remote marine boundary layer are sufficient to modify Ca-rich particles in dust storms and can play a more important role in forming a deliquescent layer on the particle surfaces as they are transported toward remote ocean regions.
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| 5.
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Maki, Teruya ; Aoki, Kazuma ; Kobayashi, Fumihisa ; Kakikawa, Makiko ; Tobo, Yutaka ; Matsuki, Atsushi ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
金沢大学理工研究域物質化学系<br />Microbial particles transported by Asian desert dust (KOSA) possibly impact ecosystems and human hea
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lth in downwind environments and are commonly called "bioaerosols." The microbial communities associated with KOSA mineral particles (KOSA bioaerosol), which were collected from the snow cover on Mt. Tateyama, were investigated by means of a culture-amendment technique combined with denaturing gradient gel electrophoresis (DGGE) analysis using 16S rRNA genes. After the stratigraphy of the snow layer formed on the walls of a snow pit on Mt. Tateyama, samples were collected from 2 layers, which included KOSA particles and one which did not. The snow samples with KOSA particles indicated microbial growth in the 100 and 10-1 dilution media and in the medium with NaCl below 10%, while the snow sample without KOSA particles showed no microbial growth in the culture media. The PCR-DGGE analysis revealed that the bacterial compositions in the snow samples including KOSA mineral particles were mainly composed of the members of the phyla Actinobacteria, Firmicutus, and Proteobacteria. In particular, the 2 phylotypes appeared in the microbial cultures were similar to the members of the B. subtilis group, which has been detected in bioaerosol samples collected from the atmosphere over KOSA arrival (Suzu City) and source (Dunhuang City) regions. Presumably, halotolerant and oligotrophic bacterial communities are associated with the KOSA particles that descend to the snow cover on Mt. Tateyama. © 2011 Springer Science+Business Media B.V.
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| 6.
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Maki, Teruya ; Kakikawa, Makiko ; Kobayashi, Fumihisa ; Yamada, Maromu ; Matsuki, Atsushi ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
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Long-range transport of airborne microorganisms through the free troposphere significantly impacts biological ecosystems
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, human life, and atmospheric processes in downwind areas. However, microbial communities in the free troposphere have rarely been investigated because the direct collection of microbial cells at high altitudes requires sophisticated sampling techniques. In this study, tropospheric air sampling was performed using a balloon and an aircraft at 800 m and 3000 m, respectively, over the Noto Peninsula in Japan (37.5°N, 137.4°E) where free tropospheric winds carry aerosols from continental areas. The air samples were collected during four different sampling periods when air masses came from desert regions of Asian continent (west samples) and from Siberia of Russia North Asia (north samples). The west samples contained higher levels of aerosols, and bacteria from the west samples grew in culture media containing up to 15% NaCl. In contrast, bacteria from the north samples could not be cultured in the same media. All isolates obtained from the NaCl-amended cultures were similar to Bacillus subtilis and classified as Firmicutes. A 16S rDNA clone library prepared from the west samples was mainly composed of one phylotype of Firmicutes that corresponded to the cultured B. subtilis sequence. A clone library prepared from the north samples consisted primarily of two phyla, i.e., Actinobacteria and Proteobacteria, which are known to dominantly inhabit low-temperature environments of North Asia. Our results suggest that airborne bacterial communities at high altitudes include several species that vary by the direction and interaction of free tropospheric winds. •Aerosol samples were collected at high altitudes using an aircraft and a balloon.•During four sampling periods, the air masses came from the Gobi Desert and North Asia.•Airborne bacterial species were investigated using a 16S rDNA clone library technique.•Bacterial species at high altitudes varied by the direction of free tropospheric winds. © 2013 Elsevier Ltd.
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| 7.
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Maki, Teruya ; Kobayashi, Fumihisa ; Yamada, Maromu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
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Bioaerosol particles including bacteria, fungi, and virus are originated from marine and terrestrial environments. The a
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irborne microorganisms are transported for long distance through the free troposphere and are thought to influence the downwind ecosystems and human life. However, microbial communities in the free troposphere have not been understood in detail because the direct sampling of microbial cells at high altitude requires sophisticated sampling techniques. In this study, for the investigation of microbial species compositions in the free troposphere, air sampling using an aircraft was performed over the Noto Peninsula in Japan, where the tropospheric winds carry aerosol particles from continental areas. Two air samples were collected at 3,000 m on March 27, 2010, when air mass was carried from the Gobi Desert to Japan area. Microorganisms from one air sample grew in culture media containing up to 15 % NaCl, suggesting that halotolerant bacteria maintain their viabilities in the free troposphere. DGGE analysis revealed that the amended cultures were dominated by Bacillus subtilis, and the isolates obtained from the amended cultures were identical to B. subtilis. Furthermore, the 16S rDNA clone library (culture-independent survey) of the other air sample grew was composed of three phylotypes belonging to Firmicutes, Bacteroidetes, and Proteobacteria with the sequences of Firmicutes phylotype corresponding to that of the cultured B. subtilis sequence. Microscopic observation using FISH method indicated that B. subtilis particles occupied 80 % of total eubacterial particles on the mineral particles. The halotolerant bacteria identical to B. subtilis would dominate at high altitudes over Noto Peninsula where the prevailing westerly wind was blowing. © 2012 Springer Science+Business Media Dordrecht.
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| 8.
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Tobo, Yutaka ; Iwasaka, Yasunobu ; Zhang, Daizhou ; Shi, Guangyu ; Kim, Yoon-Suk ; Tamura, Koichi ; Ohashi, Tetsuya
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金沢大学フロンティアサイエンス機構<br />During the Asian summer monsoon period, total ozone over the Tibetan Plateau is much lower than t
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hat over the surrounding areas when compared at the same latitudes. This phenomenon called the "ozone valley" was investigated continuously with the use of ozonesondes and Earth Probe/Total Ozone Mapping Spectrometer (EP/TOMS). These measurements reveal that although relatively low ozone mixing ratios extend from the troposphere to the lower stratosphere, those near the tropopause (between about 150 and 70 hPa) largely contribute to lower total ozone over the Tibetan Plateau. Temperatures near the tropopause appear to be correlated with the observed ozone changes. Meteorological analyses show that this phenomenon is accompanied by the upper level monsoon anticyclone, which is characterized by deep convection over South Asia. These results suggest that lower ozone mixing ratios and colder temperatures near the tropopause are primarily due to convection, which is linked to the Asian summer monsoon. Copyright 2008 by the American Geophysical Union.
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| 9.
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Maki, Teruya ; Susuki, Shinzi ; Kobayashi, Fumihisa ; Kakikawa, Makiko ; Tobo, Yutaka ; Yamada, Maromu ; Higashi, Tomomi ; Matsuki, Atsushi ; Hong, Chunsang ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
金沢大学理工研究域物質化学系<br />The microbial communities transported by Asian desert dust (KOSA) events have attracted much attenti
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on as bioaerosols because the transported microorganisms are thought to influence the downwind ecosystems in Korea and Japan. However, the atmospheric microbial community has not been investigated at high altitude in the KOSA arrival area. In this study, to estimate the viability and diversity of atmospheric halotolerant bacteria, which are expected to resist to various environmental stresses as well as high salinities, bioaerosol samples were collected at 10 and 600. m above the ground within the KOSA arrival area, Suzu City, Japan, during KOSA events. During the sampling period, the particle numbers at 600. m were higher than those at 10. m, suggesting that large particles of aerosol fall from the high altitude of 600. m to the ground surface. The microorganisms in bioaerosol samples grew in media containing up to 15% NaCl concentrations demonstrating the viability of the halotolerant bacteria in bioaerosol samples. The PCR-DGGE analysis using 16S rDNA revealed that the bacterial species in NaCl-amended cultures were similar to the bacteria detected from the genomic DNA directly extracted from the bioaerosol samples. The 16S rDNA sequences of bacterial communities in bioaerosol samples were classified into 4 phylotypes belonging to the Bacillus cereus or Bacillus subtilis group. The bioaerosol samples collected at 600. m included 2 phylotypes belonging to B. subtilis, and one phylotype among all 4 phylotypes was identical between the samples at 10 and 600. m. In the atmosphere at 600. m, the halotolerant bacterial community was expected to remain viable, and the species composition was expected to include a few species of the genus Bacillus. During this investigation period, these atmospheric bacteria may have been vertically transported to the ground surface, where the long-range KOSA particle transport from China is frequently observed. © 2010 Elsevier B.V.
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| 10.
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Yamada, Maromu ; Nakamura, Kaya ; Kameda, Takayuki ; Kobayashi, Fumihisa ; Matsuki, Atsushi ; Tsuiki, Hisanaga ; Higaki, Seigo ; Iwasaka, Yasunobu ; Hayakawa, Kazuichi
概要:
Polycyclic aromatic hydrocarbons (PAHs) are known as carcinogenic and/or mutagenic substances, and are present at high c
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oncentration in polluted environments. It has recently been reported that spore-forming bacteria (e.g., Bacillus spp.) can be transported long distances alive in the atmosphere, which raises the possibility that some of the transported bacteria could have adverse effects on human health. There is thus a need for filters that can remove gaseous PAHs from the air that people breathe and that can inhibit bacterial growth on the filters. We focused on metallophthalocyanine derivatives (M-Pc) which are known to adsorb PAHs as well as to inhibit the growth of bacteria as a potential filtering agent. In this study, we developed different types of M-Pc-supported rayon fibers by changing central metals, functional groups, concentrations of M-Pc and rayon types, and evaluated their removal effects by measuring adsorption rates of 3- and 4-ring PAHs with a HPLC and growth curves of Bacillus sp. with a spectrophotometer. The results showed that both the effects depended on functional groups and concentrations of M-Pc, and rayon types. The most effective combination was observed in Fe-Pc with sulfo group supported on cationized rayon fiber at the concentration of 2 to 3.3 wt%. Central metal species of M-Pc were influenced only on the antibacterial properties. This fiber would be applicable to filtering agents and textiles.
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