Faculty Profiles - OSADA, Kazuo

Papers - OSADA, Kazuo

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Analysis of Small-Scale Sources Based on Continuous Monitoring of Gaseous and Particulate Ammonia Concentrations Invited Reviewed Open Access

Osada Kazuo

Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi Vol. 61 ( 1 ) page： 8 - 15 2026.1

Authorship：Lead author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society for Atmospheric Environment

Ammonia in the atmosphere contributes to many ecological, environmental and climatological roles. Agriculture and livestock are recognized as the major strong sources. However, small-scale sources are also crucial for local impact on the atmospheric environment dut to the short atmospheric lifetime of ammonia. This review provides an overview of the current understanding of the effect of ammonia sources on the atmosphere, and findings from continuous measurements at Nagoya, Tokyo, and Fukuoka in Japan. It includes factors causing 1) rapid increases in ammonia concentrations after fog and dew disappearance, 2) morning increase in ammonia concentration during warm seasons when solar radiation is present, 3) simultaneous increase of NH3, NOx, CO, optical black carbon, and PM2.5 concentrations during weak winds in the winter in Tokyo, 4) 20% decrease in ammonia concentration during the first emergency declaration period of the COVID-19 pandemic in 2020, and 5) near zero concentration during the transport of acidic particles due to transboundary air pollution.

DOI： 10.11298/taiki.61.8

Open Access

CiNii Research

Determination of Ethylene Oxide and Propylene Oxide Concentrations in Air Using Derivatized Solid-Phase Collection: Evaluation of a One-Week Continuous Sampling Method and Sensitivity Improvement of Passive Samplers Reviewed Open Access

Hoshi Junya, Nudejima Chieko, Nagatsuma Hanako, Kato Mika, Saito Shinji, Osada Kazuo, Kumagai Kimiyo, Kameya Takashi

Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi Vol. 60 ( 6 ) page： 145 - 153 2025.10

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society for Atmospheric Environment

The applicability of the one-week continuous sampling method and the passive sampling method for measuring ethylene oxide and propylene oxide in ambient air was evaluated using derivatized solid-phase collection and gas chromatography-mass spectrometry. The goal was to develop a method that could more accurately calculate the annual average concentrations and conduct simplified, multi-site monitoring. A comparative test using a sampling pump showed no difference between the one-week continuous sampling method and the 24-hour sampling method (7 consecutive samples of a 24-hour collection), thus the current monitoring method for hazardous air pollutants could be applied to the one-week continuous sampling. In addition, evaluating the applicability of a commercially-available passive sampler for ambient air measurements showed that the sensitivity of the measurements was insufficient. To improve sensitivity, a new sampler with a refined design was created and evaluated, that achieved a sufficient sensitivity for ambient air measurements. The refined passive sampler’s sampling rate was calculated to be 0.00291 m3/h for ethylene oxide and 0.00248 m3/h for propylene oxide. This is more than twice the rate set by the manufacturer for the commercially-available passive sampler.

DOI： 10.11298/taiki.60.145

Open Access

CiNii Research

Antarctic haze phenomena at Syowa Station, Antarctica: seasonal features and impacts on atmospheric chemistry Reviewed Open Access

Keiichiro Hara, Kano Osato, Masanori Yabuki, Kazuo Osada, Naohiko Hirasawa, Masataka Shiobara, Takashi Yamanouchi

npj Climate and Atmospheric Science Vol. 8 ( 1 ) 2025.8

Long-Term Observation of Chemical Constituents in Atmospheric Aerosols and Gases at the Foot of Tateyama Mountain Area, Japan, from 2004 to 2017 Invited Reviewed Open Access

Kido Mizuka, Hatsushika Hiroaki, Hiyoshi Shinichiro, Osada Kazuo

Earozoru Kenkyu Vol. 40 ( 2 ) page： 75 - 83 2025.6

Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Association of Aerosol Science and Technology

Bi-weekly samples of aerosol particles, acidic gases and ammonia were collected using 4-stage filter-pack method from April 2004 to March 2017 at Tateyama Mountain area (Tateyama station, altitude: 1,180 m a.s.l.). The dominant ionic species in aerosol particles were non-sea-salt (nss) SO42− and NH4+. Long-term trends of nssSO42− and NH4+ during the period of 2005 to 2016 were −5.9 and −4.9 %/yr, respectively. NO3− concentrations were nearly unchanged. Factors contributing to seasonal variations and annual trends in these components were discussed, considering changes in emissions in Japan and China, in addition to air mass transport conditions. Observations at multiple remote sites would be useful for refining emission inventories, atmospheric chemical transport models, and further understanding of the atmospheric environment.

DOI： 10.11203/jar.40.75

Open Access

Scopus

CiNii Research

Long-term measurements of black carbon concentrations at Syowa Station, Antarctic Reviewed

Keiichiro Hara, Kazuo Osada, Masanori Yabuki, Masataka Shiobara, Naohiko Hirasawa, Takashi Yamanouchi

Polar Data Journal, Vol. 8 page： 55 - 66 2024.8

Atmospheric Aerosol and Gas Measurements at the Westernmost Large City, Fukuoka, Japan—Transboundary/Local Air Pollution and Health Effects— Reviewed Open Access

Takashima Hisahiro, Hara Keiichiro, Nishita-Hara Chiharu, Shiraishi Koichi, Hayashi Masahiko, Irei Satoshi, Kaneyasu Naoki, Ko Ryota, Kobayashi Hiroshi, Marumoto Kohji, Okuda Tomoaki, Osada Kazuo, Otobe Naohito, Takami Akinori, Uchio Eichi, Ueda Kayo, Yamazaki Akihiro, Yoshino Ayako

Earozoru Kenkyu Vol. 39 ( 2 ) page： 129 - 144 2024.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Association of Aerosol Science and Technology

Long-term observations of atmospheric aerosols and gaseous species have been conducted in Fukuoka, located in westernmost Japan, to understand the atmospheric environment of the region and to elucidate their health effects. Fukuoka represents an ideal site for studying interaction between urban air pollution originating from local urban areas in Japan and transboundary air masses from the Asian continent. Fukuoka air quality is strongly affected by transboundary transport from the Asian continent. Diurnal variations of atmospheric composition in Fukuoka are also affected by local emissions, atmospheric reactions, and local circulation. The health effects of aerosols have been investigated through epidemiological and toxicological studies. This report presents comprehensive summary of research findings obtained from studies conducted in the Fukuoka region.

DOI： 10.11203/jar.39.129

NH3 emissions from the human body in central Tokyo decreased during the COVID-19 pandemic lockdown Reviewed

Kazuo Osada, Shinji Saito, Hiroshi Tsurumaru, Syuichi Itahashi

Atmospheric Environment Vol. 318 2024.2

Comparison of Aerosol Acidity Based on a Direct Measurement Method and a Chemical Thermodynamic Model Reviewed International coauthorship Open Access

Qinping Song, Kazuo Osada

Aerosol and Air Quality Research Vol. 23 ( 11 ) page： 230096 - 230096 2023.9

Long-term monitoring of condensation nuclei concentrations at Syowa Station, Antarctic Reviewed

Keiichiro HARA, Kazuo OSADA, Masanori YABUKI, Masahiko HAYASHI, Masataka SHIOBARA, Naohiko HIRASAWA, Takashi YAMANOUCHI

Polar Data Journal Vol. 7 page： 13 - 23 2023.4

Development of a Battery-powered Automatic Switching Device for VOC Passive Samplers Reviewed Open Access

Osada Kazuo, Koyama Shinichi, Ohtsuka Katsuhiro, Hoshi Junya, Nudejima Chieko

Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi Vol. 58 ( 3 ) page： 67 - 73 2023.3

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society for Atmospheric Environment

Volatile organic compounds (VOCs) are important precursors of ozone and secondary aerosol particles in the atmosphere. We developed a battery-powered VOC passive automatic sampler (VPAS) switching device that can automatically expose and store passive VOCs solvent desorption (VOC-SD) samplers. The device can hold eight samplers at any one time. The exposure time is programmable from 1 to 99 h. A strong linear relationship was observed between the mass of the VOCs collected in the VOC-SD samplers and the product of the exposure time and atmospheric concentration (as measured by the analysis of the canister samples). The uptake rates obtained from the relationship were similar to those reported in previous studies. The VPAS will be useful in air-quality research, particularly for determining VOC sources, and will enable the measurement of VOC concentrations in remote areas where commercial alternating-current power is not available.

DOI： 10.11298/taiki.58.67

Open Access

CiNii Research

Variations in gaseous nitric acid concentrations at Tottori, Japan: Long-range transport from the Asian continent and local production Reviewed Open Access

Ryota Nojiri, Kazuo Osada, Yasunori Kurosaki, Masaya Matsuoka, Yasuhiro Sadanaga

Atmospheric Environment Vol. 274 2022.4

Language：English Publishing type：Research paper (scientific journal)

To evaluate factors affecting variation in gaseous nitric acid (HNO3) concentrations, including long-range transport from the Asian continent, we conducted continuous observations of HNO3 and related species from April 2016 to October 2017 in a coastal region near Tottori, Japan. HNO3 concentrations and concentration ratios of HNO3 to total odd nitrogen species (HNO3/NOy) during sea-breeze periods exhibited similar seasonal variations, with maximum concentrations during spring–summer and minimum concentrations during autumn–winter. The sea-breeze period concentrations were higher than those during land-breeze periods in spring–summer. Similar diurnal variations for HNO3 concentrations and HNO3/NOy with maximum values occurring during the daytime and minimum values during the nighttime were observed regardless of the season. These seasonal and diurnal variations were attributed to the reaction of NO2 with OH radicals and/or the thermal decomposition of ammonium nitrate (NH4NO3) aerosols. In terms of long-range transport from the Asian continent, a thermal equilibrium of HNO3 and gaseous ammonia (NH3) with NH4NO3 can affect variation of the HNO3 concentration. A chemical thermodynamics evaluation was conducted of the equilibrium of HNO3 and gaseous ammonia with NH4NO3. The concentration of extra ammonium ions was determined by taking into consideration that required for full neutralization of non-sea-salt sulfate in formation of ammonium sulfate, and seasonal variation in the results was evaluated. The results suggested that a thermal equilibrium of HNO3 and NH3 with NH4NO3 transported from the Asian continent could contribute to concentration variations of HNO3 in seasons other than summer.

DOI： 10.1016/j.atmosenv.2022.118988

Web of Science

Scopus

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Enhanced PM2.5 Concentrations at Urban Areas Causing by Biomass Combustion-derived Aerosol Transported from North Areas to South Areas in the Nobi Plain Reviewed Open Access

Ikemori Fumikazu, Yamagami Makiko, Hisatsune Kunihiro, Osada Kazuo

Earozoru Kenkyu Vol. 37 ( 1 ) page： 45 - 56 2022.3

Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Association of Aerosol Science and Technology

To evaluate the impact of PM2.5 transported from north areas (suburban areas) on the air quality in south areas (urban areas), time-resolved organic tracer components were measured in December 2016 both in south areas and north areas of the Nobi Plain. During PM2.5 high value events, such as December 12–13 and 26–27 2016, the concentrations of PM2.5, dicarboxylic acids and tracers of biomass burning such as levoglucosan, were high values and these temporal variations were synchronized. Moreover, the northerly wind prevailed during the observation period and the concentration of levoglucosan firstly showed a maximum value in north areas. These results demonstrated that high concentration of PM2.5 air masses originating from biomass combustion were transported from the north areas of the Nobi Plain to the south area. The characteristics of high PM2.5 events in the scatter plots between levoglucosan and optical black carbon were also supported that those air mass were transported. In addition, terephthalic acid produced by plastic combustion also showed similar behavior with levoglucosan. Our findings indicate that biomass combustion in suburban areas could significantly affect the PM2.5 in downwind urban areas in Nobi Plain.

DOI： 10.11203/jar.37.45

Open Access

CiNii Research

researchmap

Passive permeation sampling of atmospheric HNO3 Reviewed Open Access

Kazuo Osada, Koki Yamato, Qinping Song

Atmospheric Environment Vol. 267 page： 118758 2021.9

Direct measurement of aerosol acidity using pH testing paper and hygroscopic equilibrium under high relative humidity Reviewed Open Access

Qinping Song, Kazuo Osada

Atmospheric Environment Vol. 261 ( 118605 ) page： 118605 2021.9

Characterization of aerosol number size distributions and their effect on cloud properties at Syowa Station, Antarctica Reviewed Open Access

Keiichiro Hara, Chiharu Nishita-Hara, Kazuo Osada, Masanori Yabuki, Takashi Yamanouchi

Atmospheric Chemistry and Physics Vol. 21 ( 15 ) page： 12155 - 12172 2021.8

Trends in PM2.5 Concentration in Nagoya, Japan, from 2003 to 2018 and Impacts of PM2.5 Countermeasures Reviewed International journal Open Access

Makiko Yamagami, Fumikazu Ikemori, Hironori Nakashima, Kunihiro Hisatsune, Kayo Ueda, Shinji Wakamatsu, Kazuo Osada

Atmosphere Vol. 12 ( 5 ) 2021.5

Measurement report: Short-term variation in ammonia concentrations in an urban area increased by mist evaporation and emissions from a forest canopy with bird droppings Reviewed International journal Open Access

Kazuo Osada

Atmospheric Chemistry and Physics Vol. 20 ( 20 ) page： 11941 - 11954 2020.10

Spatio-temporal variations of atmospheric NH<inf>3</inf> over East Asia by comparison of chemical transport model results, satellite retrievals and surface observations Reviewed International coauthorship International journal Open Access

Wang, Z., Uno, I., Osada, K., Itahashi, S., Yumimoto, K.,Chen, X., Yang, W., Wang, Z

Atmosphere Vol. 11 ( 9 ) 2020.9

Atmospheric sea-salt and halogen cycles in the Antarctic. Invited Reviewed International journal

Hara K, Osada K, Yabuki M, Matoba S, Hirabayashi M, Fujita S, Nakazawa F, Yamanouchi T

Environmental science. Processes & impacts 2020.8

Estimating Mass Concentration Using a Low-cost Portable Particle Counter Based on Full-year Observations: Issues to Obtain Reliable Atmospheric PM2.5 Data Reviewed International journal Open Access

Ueda Sayako, Osada Kazuo, Yamagami Makiko, Ikemori Fumikazu, Hisatsune Kunihiro

ASIAN JOURNAL OF ATMOSPHERIC ENVIRONMENT Vol. 14 ( 2 ) page： 155-169 2020.6

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Papers - OSADA, Kazuo