Manually operated closed-chamber methods have been used extensively to measure CH₄ emissions from rice paddies, but the long chamber deployment time (e.g., 30 min), together with the labor required for gas sampling and subsequent analysis by gas chromatography severely limit their usefulness for multiple, high-throughput measurements. The objective of this study was to develop a modified closed-chamber method suitable for high-throughput measurements. The design of the modified system is based on a conventional method, but uses a portable spectroscopic gas analyzer and a newly developed dehumidification system. Results of a series of test operations showed that the use of a portable gas analyzer substantially reduced the time needed for each chamber deployment to as little as 4–5 min. A simple dehumidification system employing a selective water vapor-permeable tube was introduced to effectively dehumidify the sample gas so that the risk of water condensation was removed without attenuating the CH₄ concentration signal. The chamber must be equipped with a fan to ensure that the chamber air is well mixed and to attain representative CH₄ concentration values. The new method is suitable for high-throughput CH₄ emission measurements and can also be used for studying bubbling CH₄ emissions.

中文翻译：

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改进的密闭室方法提高稻田甲烷排放量的测量通量

手动操作的密闭腔室方法已广泛用于测量稻田中的CH ₄排放，但是密闭腔室的部署时间较长（例如，30分钟），再加上气体采样和随后通过气相色谱分析所需的工作量，严重限制了它们在多次高通量测量中的用处。这项研究的目的是开发一种适用于高通量测量的改进的封闭腔室方法。修改后的系统的设计基于常规方法，但是使用了便携式光谱气体分析仪和新开发的除湿系统。一系列测试操作的结果表明，使用便携式气体分析仪可将每个腔室部署所需的时间大大减少至4–5分钟。引入了一个采用选择性水蒸气可透过管的简单除湿系统，以有效地对样气除湿，从而消除了水凝结的风险，而不会降低CH的浓度。₄浓度信号。腔室必须配备风扇，以确保腔室空气充分混合并达到代表性的CH ₄浓度值。该新方法适用于高通量CH ₄排放测量，也可用于研究冒泡的CH ₄排放。