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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Simulation of enclosure-based methods for measuring gas emissions from soil to the atmosphere
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Simulation of enclosure-based methods for measuring gas emissions from soil to the atmosphere

机译：模拟基于封闭的方法测量从土壤到大气的气体排放

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Enclosure-based methods (i.e., flux chambers) have been widely used in agricultural, ecological, geophysical, and engineering studies to estimate gas exchanges at the soil-atmosphere and the water-atmosphere interfaces. In this study, the flux chambers are analyzed using diffusion theory and mass balance principle. Mathematical models are developed to simulate the general behavior of both dosed and dynamic chambers. Simulation for the closed chamber behavior shows that the flux from the enclosed soil matrix into the chamber decreases with time after chamber placement. This indicates that application of a simple linear model to calculate flux may underestimate the real flux, even though the concentration data obtained from the chamber headspace shows a relatively linear increase with respect to time. It is recommended that nonlinear models be considered whenever possible for calculating flux for closed chambers. Simulations of dynamic chambers show that (1) these chambers can reach a steady state rapidly after placement and (2) the proper measurement of flux depends on both chamber operational conditions and soil permeability to air. A dynamic chamber may underestimate the actual flux when operating on low permeable soils. On soils with high air permeability a dynamic chamber may give an underestimate of the actual flux when operating at low airflow rate but an overestimate when the airflow rate is high. Theoretically, both closed and dynamic chambers may produce accurate flux estimates if they operate under ideal conditions and appropriated models are used in flux calculations. In practice, however, a dynamic chamber should be more desirable. [References: 35]
机译：基于外壳的方法（即通量室）已广泛用于农业，生态，地球物理和工程研究中，以估计土壤-大气和水-大气界面处的气体交换。在这项研究中，使用扩散理论和质量平衡原理对通量室进行了分析。开发了数学模型来模拟剂量腔和动态腔的一般行为。对密闭室行为的仿真表明，从密闭的土壤基质到密室的通量随着密室的放置时间而降低。这表明即使从反应室顶部空间获得的浓度数据显示出相对于时间的相对线性增加，应用简单的线性模型来计算通量也可能会低估实际通量。建议在可能的情况下考虑使用非线性模型来计算封闭腔室的通量。动态腔室的仿真表明，（1）这些腔室在放置后可以迅速达到稳态;（2）通量的正确测量取决于腔室的运行条件和土壤对空气的渗透性。在低渗透性土壤上运行时，动态腔室可能会低估实际通量。在空气渗透率较高的土壤上，动力室在低风速下运行时可能会低估实际通量，而在高风速时会高估实际通量。从理论上讲，如果密闭腔室和动态腔室都在理想条件下运行并且在通量计算中使用了适当的模型，则它们都可以产生准确的通量估计值。然而，在实践中，动态腔室将是更理想的。 [参考：35]

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