ACPD Atmospheric Chemistry and Physics Discussions ACPD Atmos. Chem. Phys. Discuss. 1680-7375 Göttingen, Germany 10.5194/acp-2017-1241 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 Maki Teruya 1 Furumoto Shogo 1 Asahi Yuya 1 Lee Kevin C. https://orcid.org/0000-0003-0210-2628 2 Watanabe Koichi 3 Aoki Kazuma https://orcid.org/0000-0002-0476-357X 4 Murakami Masataka 5 Tajir Takuya 5 Hasegawa Hiroshi 1 Mashio Asami https://orcid.org/0000-0002-9975-0316 1 Iwasaka Yasunobu 6 College of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand Department of Environmental and Civil Engineering, Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan Department of Earth Sciences, Faculty of Science, University of Toyama 3190 Gofuku, Toyama 930-8555, Japan Cloud Physics Section, Forecast Research Department, Meteorological Research Institute, Nagamine 1-1, Tsukuba, Ibaraki 305-0052, Japan Community Research Service Group, University of Shiga Prefecture, 2500 Yasakamachi, Hikoneshi, Shiga, 522-8533, Japan 12 01 2018 2018 1 27 Copyright: © 2018 Teruya Maki et al. 2018 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://acp.copernicus.org/preprints/acp-2017-1241/ The full text article is available as a PDF file from https://acp.copernicus.org/preprints/acp-2017-1241/acp-2017-1241.pdf

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.

 No. 17H01616 No. G2702