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Long-term observations of ozone fluxes in a Japanese red pine forest.

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Title:	Long-term observations of ozone fluxes in a Japanese red pine forest.
Authors:	Wada, R.¹ (AUTHOR) wada@ntu.ac.jp, Miyama, T.² (AUTHOR), Kominami, Y.² (AUTHOR), Takanashi, S.² (AUTHOR), Katata, G.³ (AUTHOR), Ueyama, M.⁴ (AUTHOR), Tani, A.⁵ (AUTHOR), Yonemura, S.⁶ (AUTHOR), Takagi, K.⁷ (AUTHOR), Matsumi, Y.⁸ (AUTHOR), Kajino, M.⁹ (AUTHOR), Nakano, T.¹⁰ (AUTHOR), Takahashi, Y.¹¹ (AUTHOR), Watanabe, M.¹² (AUTHOR), Yamaguchi, M.¹³ (AUTHOR), Kinose, Y.¹⁴ (AUTHOR), Izuta, T.¹² (AUTHOR)
Source:	Atmospheric Environment. May2026, Vol. 372, pN.PAG-N.PAG. 1p.
Subject Terms:	Ozone, Ecological impact, Atmospheric deposition, Forest ecology, Red pine, Seasonal physiological variations, Micrometeorology
Abstract:	Quantifying seasonal variations in ozone (O 3) fluxes in forest ecosystems and identifying their causes are essential for characterizing the global sink and source strength of O 3 and conserving atmospheric and forest environments. We measured O 3 fluxes in a Japanese red pine (Pinus densiflora) forest located at the foothills of Mt. Fuji from 2016 to 2020 using the micrometeorological gradient method. Flux quality was validated by comparing CO 2 fluxes derived from the gradient and eddy-covariance methods, which showed good agreement. To our knowledge, this study represents the first multiyear observations of O 3 fluxes and stomatal O 3 uptake ratios in an Asian forest. The measured five-year daytime O 3 fluxes (10:00–15:00) in summer and winter were −9.6 ± 3.2 and −3.3 ± 1.8 nmol m−2 s−1, respectively. The O 3 flux in winter was approximately 30% of that in summer. The daytime O 3 concentration and flux (deposition) values peaked in spring and summer. The ratios of the stomatal O 3 uptake to the total forest O 3 deposition in summer and winter were 0.64 ± 0.28 and 0.32 ± 0.30, respectively. This ratio was among the highest reported in previous studies. A likely explanation is the relatively low ambient O 3 concentration at the observation site. The cumulative value of leaf area-based stomatal O 3 fluxes exceeding 1.6 and 1 nmol m−2 s−1 during summer was 0.7 and 1.9 mmol m−2, respectively. The Japanese red pine forests absorb a certain amount of O 3 , which has the potential to impact the ecosystem. Further studies are needed to quantify ecological impacts and underlying deposition processes. [Display omitted] • O 3 fluxes were observed in an Asian forest for five years. • O 3 fluxes were measured by the gradient method, with CO 2 fluxes for quality control. • The ratio of O 3 absorbed by stomata was high, reflecting the properties of the forest. • The cumulative O 3 absorbed by stomata was small, but its effect cannot be excluded. [ABSTRACT FROM AUTHOR]
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Database:	GreenFILE

Description
Abstract:	Quantifying seasonal variations in ozone (O 3) fluxes in forest ecosystems and identifying their causes are essential for characterizing the global sink and source strength of O 3 and conserving atmospheric and forest environments. We measured O 3 fluxes in a Japanese red pine (Pinus densiflora) forest located at the foothills of Mt. Fuji from 2016 to 2020 using the micrometeorological gradient method. Flux quality was validated by comparing CO 2 fluxes derived from the gradient and eddy-covariance methods, which showed good agreement. To our knowledge, this study represents the first multiyear observations of O 3 fluxes and stomatal O 3 uptake ratios in an Asian forest. The measured five-year daytime O 3 fluxes (10:00–15:00) in summer and winter were −9.6 ± 3.2 and −3.3 ± 1.8 nmol m−2 s−1, respectively. The O 3 flux in winter was approximately 30% of that in summer. The daytime O 3 concentration and flux (deposition) values peaked in spring and summer. The ratios of the stomatal O 3 uptake to the total forest O 3 deposition in summer and winter were 0.64 ± 0.28 and 0.32 ± 0.30, respectively. This ratio was among the highest reported in previous studies. A likely explanation is the relatively low ambient O 3 concentration at the observation site. The cumulative value of leaf area-based stomatal O 3 fluxes exceeding 1.6 and 1 nmol m−2 s−1 during summer was 0.7 and 1.9 mmol m−2, respectively. The Japanese red pine forests absorb a certain amount of O 3 , which has the potential to impact the ecosystem. Further studies are needed to quantify ecological impacts and underlying deposition processes. [Display omitted] • O 3 fluxes were observed in an Asian forest for five years. • O 3 fluxes were measured by the gradient method, with CO 2 fluxes for quality control. • The ratio of O 3 absorbed by stomata was high, reflecting the properties of the forest. • The cumulative O 3 absorbed by stomata was small, but its effect cannot be excluded. [ABSTRACT FROM AUTHOR]
ISSN:	13522310
DOI:	10.1016/j.atmosenv.2026.121901