研究者詳細 - 長田　和雄

論文 - 長田　和雄

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Long-term measurements of black carbon concentrations at Syowa Station, Antarctic 査読有り

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

Polar Data Journal, 8 巻頁： 55 - 66 2024年8月

福岡における越境/局地大気汚染・健康影響に関する研究査読有り

髙島久洋, 原圭一郎, 西田千春, 白石浩一, 林政彦, 伊禮聡, 兼保直樹, 高良太, 小林拓, 丸本幸治, 奥田知明, 長田和雄, 乙部直人, 高見昭憲, 内尾英一, 上田佳代, 山崎明宏, 吉野彩子

エアロゾル研究 39 巻 ( 2 ) 頁： 129 - 144 2024年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Earozoru Kenkyu

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

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

Osada K., Saito S., Tsurumaru H., Itahashi S.

Atmospheric Environment 318 巻 2024年2月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Atmospheric Environment

Atmospheric NH3 is emitted from various sources, such as agriculture, automobile exhaust, industrial activities, and human bodies (dermal and respiratory). Although the contribution from automobile exhaust to NH3 concentrations in urban areas is well understood, the contribution from human body emissions has not been clarified, even in densely populated areas far from agricultural and industrial sources. Tokyo, Japan, is the one of the most populated megacities in the world. During April and May 2020, socioeconomic activities in Tokyo were severely restricted to prevent the spread of the coronavirus disease (COVID-19), resulting in significant changes in human flow and automobile traffic. The sudden decrease in emissions presented a unique opportunity to clarify the contributions of human body emissions to NH3 levels. NH3 concentrations observed in central Tokyo from 2018 to 2021 decreased significantly, by about 20%, during the lockdown in 2020. No significant differences were found in wind speed or rainfall during the same period. Air quality model simulations of NH3 concentrations in the area were performed for 2019 and 2020. The simulation results for 2019 reproduced the observed NH3 concentrations and temporal variations well. However, the simulation results were overestimated for 2020. To evaluate the differences in emissions' contributions during the lockdown, sensitivity tests of NH3 emissions’ strength were conducted for 2020. The simulation in which NH3 emissions from automobiles and human bodies were reduced by 20% and 80%, respectively, reproduced the observed results well. These results indicate that emissions from human bodies and automobile traffic contribute significantly to NH3 concentrations in central Tokyo. The contributions from human body emissions to NH3 concentrations revealed in this study should be applied to update emissions factors for human bodies; clarifying human emissions factors under various conditions will improve the accuracy of air quality simulations over densely populated megacities.

DOI： 10.1016/j.atmosenv.2023.120244

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Comparison of Aerosol Acidity Based on a Direct Measurement Method and a Chemical Thermodynamic Model 査読有り国際共著

Qinping Song, Kazuo Osada

Aerosol and Air Quality Research 23 巻 ( 11 ) 頁： 230096 - 230096 2023年9月

Long-term monitoring of condensation nuclei concentrations at Syowa Station, Antarctic 査読有り

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

Polar Data Journal 7 巻頁： 13 - 23 2023年4月

VOCパッシブサンプラーのバッテリー駆動による自動切替装置の開発査読有り

長田和雄, 小山慎一, 大塚克弘, 星純也, 橳島智恵子

大気環境学会誌 58 巻 ( 3 ) 頁： 67 - 73 2023年3月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人大気環境学会

<p>大気中の揮発性有機化合物（Volatile Organic Compounds: VOCs）は、光化学反応によりオゾンやエアロゾル粒子を生成する原因物質である。近年は人為的な排出量が削減されて都市域での大気濃度は低下しつつあるが、継続的なモニタリングが必要とされている。本研究では、バッテリー駆動で自動的にパッシブサンプラー（VOCs Solvent Desorption: VOC-SD）の曝露と保管が可能なオートサンプラー（VOC Passive Automatic Sampler: VPAS）を開発した。この装置は8本の吸着管を装着できるので、1試料あたり24時間の曝露で7日分のサンプルと1つのブランクを得ることができる。比較のため、キャニスターによる標準手法（24時間採取）との同時観測を1週間行い、トルエンやエチルベンゼン、キシレンについて解析した。吸着管への捕集量と、キャニスターによる大気濃度と曝露時間の積との間には非常に良い直線関係が見られた。取り込み速度は既往研究とほぼ同様の値が得られた。また、採取時間が24時間と比較的長くても、日ごとの濃度の違いが風向頻度の違いに関連付けられることがわかった。今後、種々のVOCに対する大気濃度レベルでの取り込み速度をVPAS用に整備すれば、遠隔地あるいは商用電力の利用できない場所におけるVOC濃度の経時変化や、面的な分布を把握する際に有用である。</p>

DOI： 10.11298/taiki.58.67

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Variations in gaseous nitric acid concentrations at Tottori, Japan: Long-range transport from the Asian continent and local production 査読有り

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

ATMOSPHERIC ENVIRONMENT 274 巻 2022年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Atmospheric Environment

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

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濃尾平野の北部から南部へ向けたバイオマス燃焼由来粒子の移流による都市部のPM<sub>2.5</sub>濃度上昇査読有り

池盛文数, 山神真紀子, 久恒邦裕, 長田和雄

エアロゾル研究 37 巻 ( 1 ) 頁： 45 - 56 2022年3月