Development of a System for Simultaneous and Continuous Measurement of Carbon Dioxide, Methane and Nitrous Oxide Fluxes from Croplands Based on the Automated Closed Chamber Method
Development of a System for Simultaneous and Continuous Measurement of Carbon Dioxide, Methane and Nitrous Oxide Fluxes from Croplands Based on the Automated Closed Chamber Method
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DOI：
10.1111/j.1747-0765.2005.tb00064.x
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发表时间：
2005-08
影响因子：
2
通讯作者：
S. Nishimura;S. Sudo;H. Akiyama;S. Yonemura;K. Yagi;H. Tsuruta
中科院分区：
文献类型：
--
作者：
S. Nishimura;S. Sudo;H. Akiyama;S. Yonemura;K. Yagi;H. Tsuruta
基于密闭室法，开发了一种同时连续测量农田中二氧化碳（CO2）、甲烷（CH4）和一氧化二氮（N2O）三种主要温室气体通量的系统。在计算机控制下，放置在现场的室的顶盖定期关闭，保持关闭状态约 30 分钟，然后再次打开。在关闭腔室期间，通过气泵使腔室内的空气循环，并将部分循环空气注入气体分析仪。用红外气体分析仪监测CO2浓度，并在室关闭后1-3分钟内其增加/减少速率用于通量计算。 CH4和N2O的浓度用两台气相色谱仪测量4次，间隔8.5分钟。该系统在不同条件下的灰色低地土壤蒸渗仪田中进行了测试，包括水稻种植、旱地作物种植和休耕条件。在室关闭后的 30 分钟内，室中的 CH4 和 N2O 浓度均线性增加或几乎保持恒定。在室关闭后的 1-3 分钟内，室中的 CO2 浓度也呈线性增加（这表明作物和/或土壤微生物以呼吸性 CO2 排放为主）或降低（这表明作物以光合作用吸收 CO2 为主）。这些结果表明，可以根据足够时间间隔的气体浓度测量以及线性回归分析来估计所有三种气体的适当通量。该系统预计将有效阐明农田温室气体的综合动态，并估算农田的总净全球变暖潜力。此外，同时测量多种气体的通量对于分析气体通量的相互关系和机理也很有效。应将环境因素的变化（例如腔室关闭期间空气温度升高或光强度降低（通常称为“腔室效应”））考虑为通量数据误差的原因。
A system for simultaneous and continuous measurement of fluxes of three major greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), from croplands was developed based on the closed chamber method. Controlled by a computer, top-lids of the chambers placed in the field closed periodically, remained closed for about 30 min, and then opened again. During the closure of the chambers, the air in the chambers was circulated by air pumps, and part of the circulated air was injected to gas analyzers. CO2 concentration was monitored with an infra-red gas analyzer, and its increasing/decreasing rate during the 1-3-min period after the chamber closure was used for the flux calculation. Concentrations of CH4 and N2O were measured with two gas chromatographs 4 times at intervals of 8.5 min. The system was tested in lysimeter fields with Gray lowland soil under various conditions, including paddy rice cultivation, upland crop cultivation and also fallow condition. Both CH4 and N2O concentrations in the chambers increased linearly or remained almost constant during the 30-min period after the chamber closure. CO2 concentration in the chambers also increased (which indicates the predominance of respiratory CO2 emission by the crops and/or soil microorganisms) or decreased (which indicates the predominance of photosynthetic CO2 uptake by the crops) linearly during the 1-3-min period after the chamber closure. These results indicated that appropriate fluxes could be estimated for all the three gases based on the gas concentration measurements with adequate time intervals, and on the linear regression analyses. The system is expected to be effective for clarifying the comprehensive dynamics of greenhouse gases in, and for estimating the total net global warming potential of croplands. Furthermore, simultaneous measurement of the fluxes of multiple gases is also effective for analyzing the mutual relationships and mechanisms of the gas fluxes. Changes in environmental factors such as increase in air temperature or decrease in light intensity during the chamber closure (generally referred to as “chamber effect”) should be taken into account as a cause of error in the flux data.