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Stable Carbon Isotope Studies of CH4 Dynamics Via Water and Plant Pathways in a Tropical Thai Paddy: Insights Into Diel CH4 Transportation
Journal of Geophysical Research: Biogeosciences ( IF 3.7 ) Pub Date : 2020-08-24 , DOI: 10.1029/2019jg005112
Shujiro Komiya 1 , Tomotsugu Yazaki 2 , Fumiyoshi Kondo 3 , Kentaro Katano 4, 5 , Jost V. Lavric 1 , Iain McTaggart 2 , Tiwa Pakoktom 6 , Meechai Siangliw 7 , Theerayut Toojinda 7 , Kosuke Noborio 2
Affiliation  

Separate evaluation of methane (CH4) emission dynamics (e.g., oxidation, production, and transportation) at the soil‐plant‐atmosphere and soil‐water‐atmosphere interfaces has been limited in tropical rice paddies, but it is crucial for comprehending the entire CH4 cycles. We investigated CH4 oxidation, production, and transportation through plant and water pathways during the reproductive stage in a tropical Thailand rice paddy field using natural abundance carbon stable isotope ratios (δ13CH4 and δ13CO2). Mass balance equations using δ13CH4 and δ13CO2 in soil gases indicated that CH4 oxidation in the planted soil exceeded those in the interrow soil due to oxygen supply through rice roots. In addition, at 1–11 cm depth acetate fermentation was the dominant process in the planted soil, whereas in the interrow soil the dominant process was H2/CO2 reduction. The water pathway showed a significant negative correlation between CH4 flux and released δ13CH4 over 24 hr, driven by a diel change in episodic ebullition, steady ebullition, and diffusion, all due to diel changes in soil temperature and atmospheric pressure. In contrast, the plant pathway showed a significant positive relationship between CH4 flux and emitted δ13CH4 throughout one day. A comparison of the diel change in emitted δ13CH4 between the water and plant pathways showed that the rice plants transported CH4 in soil bubbles without any large isotopic fractionation. The diel change in the plant‐mediated CH4 transportation was mainly controlled by diel changes in soil bubble expansion and CH4 diffusion through plants, which were probably regulated by diel changes in soil temperature and atmospheric pressure.

中文翻译:

热带泰国稻中通过水和植物途径的CH4动力学的稳定碳同位素研究:对Diel CH4运输的认识

在热带稻田中,对土壤-植物-大气和土壤-水-大气界面处甲烷(CH 4)排放动态(例如,氧化,生产和运输)的单独评估是有限的,但对于理解整个过程至关重要CH 4个周期。我们研究了CH 4使用天然丰度稳定的碳同位素比率(δ在生殖阶段的氧化,生产,运输和通过植物和水通路在热带泰国稻田13 CH 4和δ 13 CO 2)。使用δ质量平衡方程13 CH 4和δ 13 CO 2土壤气体中的甲烷表明,由于通过稻根提供的氧气,种植土壤中的CH 4氧化超过了行间土壤中的CH 4氧化。此外,在1–11 cm深度,醋酸盐发酵是种植土壤的主要过程,而行间土壤的主要过程是H 2 / CO 2还原。水通路表明CH之间的显著负相关4通量和释放δ 13 CH 4超过24小时,通过在沸腾发作,稳定沸腾,和扩散一个昼夜变化,所有由于在土壤温度和大气压力的变化昼夜驱动。相反,植物途径显示CH 4之间显着正相关通量和δ发射13 CH 4在整个一天。的昼夜变化中发射的δ的比较13 CH 4的水和植物途径之间显示,水稻植物输送CH 4在土壤而没有任何大的同位素分馏气泡。植物介导的CH 4运移中的狄尔变化主要受土壤气泡膨胀和植物中CH 4扩散的狄尔变化控制,这可能受土壤温度和大气压力的狄尔变化控制。
更新日期:2020-09-11
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