Exploring sub-daily to seasonal variations in methane exchange in a single-crop rice paddy in central Japan
Exploring sub-daily to seasonal variations in methane exchange in a single-crop rice paddy in central Japan
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DOI：
10.1016/j.atmosenv.2018.02.015
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发表时间：
2018-04
影响因子：
5
通讯作者：
H. Iwata;M. Mano;K. Ono;T. Tokida;Takahiro Kawazoe;Y. Kosugi;Ayaka Sakabe;Kenshi Takahashi;A. Miyata
中科院分区：
文献类型：
--
作者：
H. Iwata;M. Mano;K. Ono;T. Tokida;Takahiro Kawazoe;Y. Kosugi;Ayaka Sakabe;Kenshi Takahashi;A. Miyata
利用涡度相关技术观测了日本中部（关东地区）稻田甲烷（CH4）交换的季节变化，以阐明不同耕作阶段环境控制对CH4交换的影响。水稻抽穗前的CH4排放主要受风速和地温的影响.土壤温度的依赖性可能是由于在较高的土壤温度下，CH4的产生增加，更高的分子扩散和更高的电导率在水稻植株内。从风速依赖性也建议发生沸腾排放。抽穗后，相对湿度和水温对CH4排放有影响.排放量的日变化幅度从抽穗前后期的0.03 μ mol m− 2 s− 1增加到抽穗后的0.13 μ mol m− 2 s− 1。水稻通气组织内诱导的对流通流的植物结构的变化是由于这种变化在抽穗后的环境控制。排水后，CH4排放仅限于强降雨事件后的短时间内。水位控制排放的时间，最有可能通过影响从缺氧土壤到大气的扩散效率和CH4在表面好氧区的氧化。在陆地生态系统模式中，需要考虑主要传输途径的变化，以准确预测稻田CH4排放。
Abstract Season-long methane (CH 4) exchange was observed in a rice paddy field in central Japan (Kanto Region) using the eddy covariance technique to clarify the variations in environmental controls on CH 4 exchange in different stages of cultivation. Before heading of rice plant, the CH 4 emission depended on wind speed and soil temperature. The soil temperature dependence can be due to an increase in CH 4 production, higher molecular diffusion, and higher conductance within rice plant at higher soil temperature. An occurrence of ebullitive emission was also suggested from the wind speed dependence. After heading was completed, relative humidity and water temperature influenced CH 4 emission. The amplitude of the diurnal variation in emission increased from 0.03 μ mol m− 2 s− 1 in the late pre-heading stage to 0.13 μ mol m− 2 s− 1 in the post-heading stage. Induced convective throughflow within the rice aerenchyma after the change in plant structure was attributable to this variation in environmental controls after the heading. After drainage, CH 4 emission was confined to short periods after strong rain events. The water level controlled the timing of emission, most likely by influencing the diffusion efficiency from the anoxic soil to the atmosphere and CH 4 oxidation in the surface oxic zone. The variation in the dominant transport pathway needs to be accounted for in terrestrial ecosystem models to accurately predict CH 4 emission from rice paddies.