TY  - JOUR
A1  - Komiya, Shujiro
A1  - Yazaki, Tomotsugu
A1  - Kondo, Fumiyoshi
A1  - Katano, Kentaro
A1  - Lavric, Jost V.
A1  - McTaggart, Iain
A1  - Pakoktom, Tiwa
A1  - Siangliw, Meechai
A1  - Toojinda, Theerayut
A1  - Noborio, Kosuke
T1  - Stable Carbon Isotope Studies of CH4 Dynamics Via Water and Plant Pathways in a Tropical Thai Paddy: Insights Into Diel CH4 Transportation
Y1  - 2020
VL  - 125
IS  - 9
JF  - Journal of Geophysical Research: Biogeosciences
DO  - 10.1029/2019JG005112
DO  - 10.23689/fidgeo-5027
N2  - 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.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9373
ER  -