scholarly journals Characterization of atmospheric bioaerosols along the transport pathway of Asian dust during the Dust-Bioaerosol 2016 Campaign

2018 ◽  
Vol 18 (10) ◽  
pp. 7131-7148 ◽  
Author(s):  
Kai Tang ◽  
Zhongwei Huang ◽  
Jianping Huang ◽  
Teruya Maki ◽  
Shuang Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Relative Abundance ◽  
Bacterial Communities ◽  
Asian Dust ◽  
Dust Aerosol ◽  
Sequencing Analysis ◽  
Transport Pathway ◽  
Surface Sand ◽  
Relative Abundances ◽  
Dust Events

Abstract. Previous studies have shown that bioaerosols are injected into the atmosphere during dust events. These bioaerosols may affect leeward ecosystems, human health, and agricultural productivity and may even induce climate change. However, bioaerosol dynamics have rarely been investigated along the transport pathway of Asian dust, especially in China where dust events affect huge areas and massive numbers of people. Given this situation, the Dust-Bioaerosol (DuBi) Campaign was carried out over northern China, and the effects of dust events on the amount and diversity of bioaerosols were investigated. The results indicate that the number of bacteria showed remarkable increases during the dust events, and the diversity of the bacterial communities also increased significantly, as determined by means of microscopic observations with 4,6-diamidino-2-phenylindole (DAPI) staining and MiSeq sequencing analysis. These results indicate that dust clouds can carry many bacteria of various types into downwind regions and may have potentially important impacts on ecological environments and climate change. The abundances of DAPI-stained bacteria in the dust samples were 1 to 2 orders of magnitude greater than those in the non-dust samples and reached 105–106 particles m−3. Moreover, the concentration ratios of DAPI-stained bacteria to yellow fluorescent particles increased from 5.1 % ± 6.3 % (non-dust samples) to 9.8 % ± 6.3 % (dust samples). A beta diversity analysis of the bacterial communities demonstrated the distinct clustering of separate prokaryotic communities in the dust and non-dust samples. Actinobacteria, Bacteroidetes, and Proteobacteria remained the dominant phyla in all samples. As for Erenhot, the relative abundances of Acidobacteria and Chloroflexi had a remarkable rise in dust events. In contrast, the relative abundances of Acidobacteria and Chloroflexi in non-dust samples of R-DzToUb were greater than those in dust samples. Alphaproteobacteria made the major contribution to the increasing relative abundance of the phylum Proteobacteria in all dust samples. The relative abundance of Firmicutes did not exceed 5 % in all the air samples, even though it is the predominant phylum in the surface sand samples from the Gobi Desert. These results illustrate that the bacterial community contained in dust aerosol samples has a different pattern compared with non-dust aerosol samples, and the relative abundances of airborne bacteria are different from those in the surface sand or soil and differ by location and transmitting vector.

scholarly journals Characterization of atmospheric bioaerosols along the transport pathway of Asian dust during the Dust-Bioaerosol 2016 Campaign

2017 ◽  
Author(s):  
Kai Tang ◽  
Zhongwei Huang ◽  
Jianping Huang ◽  
Teruya Maki ◽  
Shuang Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Bacterial Communities ◽  
Northern China ◽  
Asian Dust ◽  
Sequencing Analysis ◽  
Dapi Staining ◽  
Transport Pathway ◽  
Dust Clouds ◽  
Airborne Microbes ◽  
Dust Events

Abstract. Previous studies have shown that bioaerosols are injected into the atmosphere during dust events. These bioaerosols may affect leeward ecosystems, human health and agricultural productivity and may even induce climate change. However, bioaerosol dynamics have rarely been investigated along the transport pathway of Asian dust, especially in China, where dust events affect huge areas and massive numbers of people. Given this situation, the Dust-Bioaerosol (DuBi) Campaign was carried out over northern China, and the effects of dust events on the amount and diversity of bioaerosols were investigated. The results indicate that the number of bacteria showed remarkable increases during the dust events, and the diversity of the bacterial communities also increased significantly, as determined by means of microscopic observations with 4,6-diamidino-2-phenylindole (DAPI) staining and MiSeq sequencing analysis. These results indicate that dust clouds can carry many bacteria of various types into downwind regions and may have potentially important impacts on ecological environments and climate change. The abundances of DAPI-stained bacteria in the dust samples were one to two orders of magnitude greater than those in the non-dust samples and reached 105 ~ 106 particles m−3. Moreover, the charge capacity of yellow fluorescent particles associated with the DAPI-stained bacteria increased from 5.1 % ± 6.3 % (non-dust samples) to 9.8 % ± 6.3 % (dust samples). A beta diversity analysis of the bacterial communities demonstrated the distinct clustering of separate prokaryotic communities in the dust and non-dust samples. Actinobacteria, Bacteroidetes, Proteobacteria remained the dominant phyla in all samples. As for Erenhot, the relative amounts of Acidobacteria and Chloroflexi have a remarkable rise in dust events. Alphaproteobacteria made the major contribution of the increasing relative amounts of the phylum proteobacteria in all dust samples. In the future, the viability and activity of airborne microbes, the interactions between bioaerosols and other gaseous and solid components in the air, and the effects of bioaerosols on animals and plants, ecological environments and the climate system must be studied in depth to help us understand the behavior of bioaerosols in the air and dust clouds in greater detail.

scholarly journals Variations in airborne bacterial communities at high altitudes over the Noto Peninsula (Japan) in response to Asian dust events

2017 ◽  
Author(s):  
Teruya Maki ◽  
Kazutaka Hara ◽  
Ayumu Iwata ◽  
Kevin C. Lee ◽  
Kei Kawai ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Asian Dust ◽  
Free Troposphere ◽  
High Altitudes ◽  
Air Masses ◽  
Air Samples ◽  
Westerly Winds ◽  
Continental Area ◽  
Sand Particles ◽  
Dust Events

Abstract. Aerosol particles, including airborne microorganisms, are transported through the free troposphere from the Asian continental area to the downwind area in East Asia and can influence climate changes, ecosystem dynamics, and human health. However, the variations present in airborne bacterial communities in the free troposphere over downwind areas are poorly understood, and there are few studies that provide an in-depth examination of the effects of long-range transport of aerosols (natural and anthropogenic particles) on bacterial variations. In this study, the vertical distributions of airborne bacterial communities at high altitudes were investigated and the bacterial variations were compared between dust events and non-dust events. Aerosols were collected at three altitudes from ground level to the free troposphere (upper level: 3,000 m or 2,500 m; middle level: 1,200 m or 500 m; and low level: 10 m) during Asian dust events and non-dust events over the Noto Peninsula, Japan, where westerly winds carry aerosols from the Asian continental areas. During Asian dust events, air masses at high altitudes were transported from the Asian continental area by westerly winds, and Laser Imaging Detection and Ranging (LiDAR) data indicated high concentrations of non-spherical particles, suggesting that dust-sand particles were transported from the central desert regions of Asia. The air samples collected during the dust events contained 10–100 times higher concentrations of microscopic fluorescent particles and Optical Particle Counter (OPC) measured particles than in non-dust events. The air masses of non-dust events contained lower amounts of dust-sand particles. Additionally, some air samples showed relatively high levels of black carbon, which were likely transported from the Asian continental coasts. Moreover, during the dust events, microbial particles at altitudes of > 1,200 m increased to the concentrations ranging from 1.2 × 106 particles m−3 to 6.6 × 106 particles m−3. In contrast, when dust events disappeared, the microbial particles at > 1,200 m decreased slightly to microbial-particle concentrations ranging from 6.4 × 104 particles m−3 to 8.9 × 105 particles m−3. High-throughput sequencing technology targeting 16S rRNA genes (16S rDNA) revealed that the bacterial communities collected at high altitudes (from 500 m to 3,000 m) during dust events exhibited higher diversities and were predominantly composed of natural-sand/terrestrial bacteria, such as Bacillus members. During non-dust periods, airborne bacteria at high altitudes were mainly composed of anthropogenic/terrestrial bacteria, (Actinobacteria), marine bacteria (Cyanobacteria and Alphaproteobacteria), and plant-associated bacteria (Gammaproteobacteria), which shifted in composition in correspondence with the origins of the air masses and the meteorological conditions. Heterogeneous bacterial populations, originating from terrestrial, marine, and plant-associated categories, were used as an indicator for the mixture levels of air masses originating from the Asian continental area, the Sea of Japan, and the Japanese islands, respectively. The airborne bacterial structures at high altitudes suggested remarkable changes in response to air mass sources, which contributed to the increases in community richness and to the domination of a few bacterial taxa.

scholarly journals Long-range transported bioaerosols captured in snow cover on Mount Tateyama, Japan: Impacts of Asian-dust events on airborne bacterial dynamics relating to ice-nucleation activities

2018 ◽  
Author(s):  
Teruya Maki ◽  
Shogo Furumoto ◽  
Yuya Asahi ◽  
Kevin C. Lee ◽  
Koichi Watanabe ◽  
...  
Keyword(s):  
Snow Cover ◽  
Long Range ◽  
Bacterial Communities ◽  
Aerosol Particles ◽  
Ice Nucleation ◽  
Asian Dust ◽  
Dust Particles ◽  
Bacterial Dynamics ◽  
Dust Events ◽  
Snow Samples

Abstract. The westerly wind travelling at high altitudes over East Asia transports aerosols from the Asian deserts and urban areas to downwind areas such as Japan. These long-range transported aerosols include not only mineral particles, but also microbial particles (bioaerosols), that impact the ice-cloud formation processes as ice nuclei. However, the the detailed relations of airborne bacterial dynamics to ice nucleation in high-elevation aerosols have not been investigated. Here, we used the aerosol particles captured in the snow cover at the altitudes of 2450 m on Mt. Tateyama to investigate the sequential changes of ice-nucleation activities and bacterial communities in aerosols and elucidate the relationships between the two processes. After stratification of the snow layers formed on the walls of a snow pit on Mt. Tateyama, snow samples, including aerosol particles, were collected from 70 layers at the lower (winter accumulation) and upper (spring accumulation) parts of the snow wall. The aerosols recorded in the lower parts mainly came from Siberia (Russia), North Asia, and the Sea of Japan, while those in the upper parts showed an increase the Asian-dust particles, which originate from the desert regions and industrial coasts of Asian. The snow samples exhibited high levels of ice nucleation corresponding to the increase of Asian dust particles. Amplicon sequencing analysis using 16S rRNA genes revealed that the bacterial communities in the snow samples predominately included plant associated and marine bacteria (phyla Proteobacteria) during winter; whereas, during spring, when dust events arrived frequently, the majority were terrestrial bacteria of phyla Actinobacteria and Firmicutes. The relative abundances of Firmicutes (Bacilli) showed a significant positive relationship to the ice nucleation in snow samples. Presumably, Asian dust events change the airborne bacterial communities over Mt. Tateyama and carry terrestrial bacterial populations, which possibly induce ice-nucleation activities, thereby indirectly effecting on climate changes.

Bacillus-Dominant Airborne Bacterial Communities Identified During Asian Dust Events

2019 ◽  
Vol 78 (3) ◽  
pp. 677-687 ◽  
Author(s):  
Keunje Yoo ◽  
Il Han ◽  
Kwan Soo Ko ◽  
Tae Kwon Lee ◽  
Hyunji Yoo ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Asian Dust ◽  
Dust Events

scholarly journals Variations in airborne bacterial communities at high altitudes over the Noto Peninsula (Japan) in response to Asian dust events

2017 ◽  
Vol 17 (19) ◽  
pp. 11877-11897 ◽  
Author(s):  
Teruya Maki ◽  
Kazutaka Hara ◽  
Ayumu Iwata ◽  
Kevin C. Lee ◽  
Kei Kawai ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Asian Dust ◽  
Free Troposphere ◽  
High Altitudes ◽  
Air Masses ◽  
Air Samples ◽  
Westerly Winds ◽  
Continental Area ◽  
Sand Particles ◽  
Dust Events

Abstract. Aerosol particles, including airborne microorganisms, are transported through the free troposphere from the Asian continental area to the downwind area in East Asia and can influence climate changes, ecosystem dynamics, and human health. However, the variations present in airborne bacterial communities in the free troposphere over downwind areas are poorly understood, and there are few studies that provide an in-depth examination of the effects of long-range transport of aerosols (natural and anthropogenic particles) on bacterial variations. In this study, the vertical distributions of airborne bacterial communities at high altitudes were investigated and the bacterial variations were compared between dust events and non-dust events.Aerosols were collected at three altitudes from ground level to the free troposphere (upper level: 3000 or 2500 m; middle level: 1200 or 500 m; and low level: 10 m) during Asian dust events and non-dust events over the Noto Peninsula, Japan, where westerly winds carry aerosols from the Asian continental areas. During Asian dust events, air masses at high altitudes were transported from the Asian continental area by westerly winds, and laser imaging detection and ranging (lidar) data indicated high concentrations of non-spherical particles, suggesting that dust-sand particles were transported from the central desert regions of Asia. The air samples collected during the dust events contained 10–100 times higher concentrations of microscopic fluorescent particles and optical particle counter (OPC) measured particles than in non-dust events. The air masses of non-dust events contained lower amounts of dust-sand particles. Additionally, some air samples showed relatively high levels of black carbon, which were likely transported from the Asian continental coasts. Moreover, during the dust events, microbial particles at altitudes of  >  1200 m increased to the concentrations ranging from 1. 2 × 106 to 6. 6 × 106 particles m−3. In contrast, when dust events disappeared, the microbial particles at  >  1200 m decreased slightly to microbial-particle concentrations ranging from 6. 4 × 104 to 8. 9 × 105 particles m−3.High-throughput sequencing technology targeting 16S rRNA genes (16S rDNA) revealed that the bacterial communities collected at high altitudes (from 500 to 3000 m) during dust events exhibited higher diversities and were predominantly composed of natural-sand/terrestrial bacteria, such as Bacillus members. During non-dust periods, airborne bacteria at high altitudes were mainly composed of anthropogenic/terrestrial bacteria (Actinobacteria), marine bacteria (Cyanobacteria and Alphaproteobacteria), and plant-associated bacteria (Gammaproteobacteria), which shifted in composition in correspondence with the origins of the air masses and the meteorological conditions. The airborne bacterial structures at high altitudes suggested remarkable changes in response to air mass sources, which contributed to the increases in community richness and to the domination of a few bacterial taxa.

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

2018 ◽  
Vol 72 ◽  
pp. 133-139 ◽  
Author(s):  
Jonguk Park ◽  
Pin-Fang Li ◽  
Tomoaki Ichijo ◽  
Masao Nasu ◽  
Nobuyasu Yamaguchi
Keyword(s):  
Bacterial Communities ◽  
Source Region ◽  
Asian Dust ◽  
Dust Events

scholarly journals Long-range-transported bioaerosols captured in snow cover on Mount Tateyama, Japan: impacts of Asian-dust events on airborne bacterial dynamics relating to ice-nucleation activities

2018 ◽  
Vol 18 (11) ◽  
pp. 8155-8171 ◽  
Author(s):  
Teruya Maki ◽  
Shogo Furumoto ◽  
Yuya Asahi ◽  
Kevin C. Lee ◽  
Koichi Watanabe ◽  
...  
Keyword(s):  
Snow Cover ◽  
Long Range ◽  
Bacterial Communities ◽  
Aerosol Particles ◽  
Ice Nucleation ◽  
Asian Dust ◽  
Dust Particles ◽  
Bacterial Dynamics ◽  
Dust Events ◽  
Snow Samples

Abstract. The westerly wind travelling at high altitudes over eastern Asia transports aerosols from the Asian deserts and urban areas to downwind areas such as Japan. These long-range-transported aerosols include not only mineral particles but also microbial particles (bioaerosols), that impact the ice-cloud formation processes as ice nuclei. However, the detailed relations of airborne bacterial dynamics to ice nucleation in high-elevation aerosols have not been investigated. Here, we used the aerosol particles captured in the snow cover at altitudes of 2450 m on Mt Tateyama to investigate sequential changes in the ice-nucleation activities and bacterial communities in aerosols and elucidate the relationships between the two processes. After stratification of the snow layers formed on the walls of a snow pit on Mt Tateyama, snow samples, including aerosol particles, were collected from 70 layers at the lower (winter accumulation) and upper (spring accumulation) parts of the snow wall. The aerosols recorded in the lower parts mainly came from Siberia (Russia), northern Asia and the Sea of Japan, whereas those in the upper parts showed an increase in Asian dust particles originating from the desert regions and industrial coasts of Asia. The snow samples exhibited high levels of ice nucleation corresponding to the increase in Asian dust particles. Amplicon sequencing analysis using 16S rRNA genes revealed that the bacterial communities in the snow samples predominately included plant associated and marine bacteria (phyla Proteobacteria) during winter, whereas during spring, when dust events arrived frequently, the majority were terrestrial bacteria of phyla Actinobacteria and Firmicutes. The relative abundances of Firmicutes (Bacilli) showed a significant positive relationship with the ice nucleation in snow samples. Presumably, Asian dust events change the airborne bacterial communities over Mt Tateyama and carry terrestrial bacterial populations, which possibly induce ice-nucleation activities, thereby indirectly impacting climate change.

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