벼재배 논에서 온실가스 측정을 위해 사용되는 closed 챔버법은 시·공간적으로 변동 폭이 큰 메탄 플럭스를 측정하는 데는 한계가 있다. 이러한 문제점을 해결하고자 메탄플럭스 측정에 있어 에디공분산을 기반으로 하는 open-path 방법과 closed 챔버법을 비교분석하였다.
벼 재배 기간 중 메탄 플럭스 변동은 두 방법 모두 비슷한 경향을 보였고 closed 챔버를 이용한 메탄 측정 시간대의 값은 open-path 측정에 의한 값과 고도로 유의한 상관을 보였다. 다만 총배출량에 있어서 두 측정 방법 간에 나타난 약 31%의 차이가 발생했는데 이는 closed 챔버법에 따른 과다측정과 open-path에 의한 과소측정으로 생각해 볼 수 있다. 정확한 원인 분석을 위해서 향후에도 추가적인 연구가 필요할 것으로 판단된다.
The closed chamber method, which is one of the most commonly used method for measuring greenhouse gases produced in rice paddy fields, has limitations in measuring dynamic CH4 flux with spatio-temporal constrains. In order to deal with the limitation of the closed chamber method, some studies based on open-path of eddy covariance method have been actively conducted recently. The aim of this study was to compare the CH4 fluxes measured by open-path and closed chamber method in the paddy rice fields. The open-path, one of the gas (CO2, CH4 etc.) analysis methods, is technology where a laser beam is emitted from the source passes through the open cell, reflecting multiple times from the two mirrors, and then detecting. The CH4 emission patterns by these two methods during rice cultivation season were similar, but the total CH4 emission measured by open-path method were 31% less than of the amount measured by closed chamber. The reason for the difference in CH4 emission was due to overestimation by closed chamber and underestimation by open-path. The closed chamber method can overestimate CH4 emissions due to environmental changes caused by high temperature and light interruption by acrylic partition in chamber. On the other hand, the open-path method for eddy covariance can underestimate its emission because it assumes density fluctuations and horizontal homogeneous terrain negligible However, comparing CH4 fluxes at the same sampling time (AM 10:30-11:00, 30-min fluxes) showed good agreements (r2=0.9064). The open-path measurement technique is expected to be a good way to compensate for the disadvantage of the closed chamber method because it can monitor dynamic CH4 fluctuation even if data loss is taken into account.