295-6 CH4, CO2 Exchanges at Plant-Atmosphere and Water-Atmosphere Interfaces in Tropical Rice Paddy Fields.

Poster Number 304

See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: Global Climate Change: II (includes student competition)

Tuesday, November 17, 2015
Minneapolis Convention Center, Exhibit Hall BC

Shujiro Komiya1, Kosuke Noborio2, Kentaro Katano3, Tiwa Pakoktom4, Meechai Siangliw5 and Theerayut Toojinda5, (1)1-1-1 Higashi-Mita, Tama-ku, Meiji University, Kawasaki, Kanagawa, JAPAN
(2)Agriculture, Meiji University, Kawasaki, Japan
(3)kawasaki, kanagawa, Japan, Formerly Meiji University, Kawasaki, Japan
(4)Department of Agronomy,, Kasetsart University, Kamphaengsaen, Thailand
(5)Rice Gene Discovery Unit, National Center for Genetic Engineering and Biotechnology, Kasetsart University, Kamphaengsaen, Thailand
Abstract:
The comprehensive studies on methane (CH4) and carbon dioxide (CO2) exchanges between interfaces in rice paddy fields will gain the better knowledge of CH4 and CO2 balance in the globe. Using stable isotopes is a useful method for understanding the mechanisms of CH4 and CO2 exchanges in the ecosystem. Although CH4 and CO2 directly exchange between plants and the atmosphere or between the water surface and the atmosphere in rice paddy fields, research on exploring those exchanges at each interface has been limited. Here, we report the results of our field experiments on the CH4 and CO2 exchanges between the interfaces using stable isotope techniques. Research was conducted from September 18 to 27, 2014 in a farming rice paddy field of Kasetart University, Kamphaeng Saen campus in Thailand. The CH4 and CO2 fluxes were measured every hour using two automated closed chambers: one for the plant-atmosphere interface covering a rice hill, and the other for the water-atmosphere interface covering the water surface between rice plants. The CH4/CO2 concentrations, δ13C-CH4 andδ13C-CO2 in the chamber headspace air were analyzed using a wavelength-scanned cavity ring-down spectroscopy CH4/CO2 analyzer (G2201-i, Picarro Inc., Santa Clara, CA, USA). Diurnal changes in CH4 emission at the plant-atmosphere interface seemed to correspond to soil temperature. The CH4 emission at the water-atmosphere interface was dominated by bubble ebullition in the daytime and by molecular diffusion in the nighttime. The CH4 ebullitions were most likely controlled by decreases in atmospheric pressure and increases in soil temperature. The δ13C-CH4 values from the rice plant increased with increasing CH4 emission rates in daytime. The δ13C-CH4 values from paddy water was lower in the daytime than in the nighttime. The CO2 dynamics in paddy fields will be discussed as well.

See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: Global Climate Change: II (includes student competition)