Fluxes of CH4 and CO2 over the rice paddy using relaxed eddy accumulation method

• Main Authors: Chin-Hao Chang, 張晉豪
• Other Authors: 莊秉潔
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/86595855976664473406

碩士 === 中興大學 === 環境工程學系所 === 99 === In this study, a field measurement of CH4 and CO2 fluxes was conducted by using the Relaxed Eddy Accumulation (REA) method and the eddy covariance (EC) technique over rice paddies at Wu-Fong Agricultural Research Institute during 2011/4/27 ~ 2011/5/9. The new REA system was modified from the previous system to improve the accuracy, which included the minimum of the system, sample dryer and the reduction of sampling tube length. Theβ values in the REA method calculated from the fluxes of CO2, water vapor and sensible haet from the EC system were 0.38, 0.38 and 0.39, respectively. The statistical results showed that β from sensible heat flux was better than others. Therefore, β value was assigned as 0.38 in this study. The R2 of EC and REA systems was 0.5352 and therefore, it was considered reasonable and credible for the REA system. The CO2 average emissions were 11.8 g /m2/day and 2.6 g/m2/day by EC and REA, respectively. The CH4 flux measured by REA was 12.92 mg /m2/day and the total emission was 138.6 mg/m2 during study period. The methane fluxes were higher during daytime compared with those in the nighttime, which ranged for 0.04 to 0.38 μg /m2/s.