Diurnal and phenological variations of O₃ and CO₂ fluxes of rice canopy exposed to different O₃ concentrations

A dynamic chamber system was designed to measure simultaneously the diurnal and phenological canopy ozone (O₃) and carbon dioxide (CO₂) fluxes in the paddy field under different O₃ concentrations (0, 40, 80 and 120 nmol mol⁻¹). On the diurnal timescale, a decreasing trend of canopy O₃ flux was obser...

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Bibliographic Details
Published in:Atmospheric environment (1994) 2011-10, Vol.45 (31), p.5621-5631
Main Authors: Tong, Lei, Wang, Xiaoke, Geng, Chunmei, Wang, Wei, Lu, Fei, Song, Wenzhi, Liu, Hongjie, Yin, Baohui, Sui, Lihua, Wang, Qiong
Format: Article
Language:English
Subjects:
Applied sciences
atmospheric chemistry
Atmospheric pollution
canopy
carbon dioxide
cultivars
environmental factors
Exact sciences and technology
growing season
leaf area index
Oryza sativa
ozone
paddies
photosynthesis
photosynthetically active radiation
Pollution
prediction
rice
senescence
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Summary:A dynamic chamber system was designed to measure simultaneously the diurnal and phenological canopy ozone (O₃) and carbon dioxide (CO₂) fluxes in the paddy field under different O₃ concentrations (0, 40, 80 and 120 nmol mol⁻¹). On the diurnal timescale, a decreasing trend of canopy O₃ flux was observed from morning to evening and the O₃ flux increased with increasing O₃ concentration, while canopy CO₂ flux generally followed the track of photosynthetic active radiation, with higher values at noon except at the end of the growing season when rice was senescent. The constant CO₂ flux among different O₃ treatments in this experiment suggested that the photosynthesis of the rice canopy was not affected by short-duration (ca. 10 min) O₃ exposure of elevated concentration. The daily mean O₃ and CO₂ fluxes increased with rice growth until the dough stage and the late jointing stage, respectively, then decreased with rice aging. The peak values of O₃ flux appeared later than those of CO₂ flux because the latter was closely synchronized with the leaf area index of the rice canopy. Diurnal mean canopy O₃ flux varied from 18.7 to 43.3 nmol m⁻² s⁻¹, and nocturnal mean canopy O₃ flux varied from 2.7 to 17.8 nmol m⁻² s⁻¹ and from 7.0 to 25.4 nmol m⁻² s⁻¹ for the 40 and 80 nmol mol⁻¹ O₃ treatments, respectively. The considerable amount of nocturnal O₃ flux indicated a significant contribution of non-stomatal factors to canopy O₃ uptake. The adjusted Jarvis multiplicative models were used and well parameterized to fit the measured O₃ and CO₂ fluxes of our rice cultivar from environmental variables. Although more validation work is needed, the present results suggest that the models can be considered as a tool for canopy flux predictions in the paddy field.
ISSN:1352-2310
1873-2844
DOI:10.1016/j.atmosenv.2011.03.070