The physical processes governing advective and diffusive gas movement and distribution in dry soils are, in general, well understood and quantified. In this study, we derived and applied analytical and numerical models to describe these processes under different conditions and scenarios and conducted gas flow experiments in 200‐L barrels packed with dry quartz sand in a temperature‐controlled laboratory. We used either pure N₂ (0% O₂) or atmospheric air (20.9% O₂) injection or gas extraction from (or into) buried point sources (or sinks) to examine the effects of (a) source depth, (b) source discharge rate, and (c) injection cycle period on gas concentration and pressure distribution. We further quantified the contribution of diffusion from the atmospheric soil surface for the different scenarios, made possible by injecting N₂ and tracking the complementary O₂ concentration [i.e. the difference between atmospheric (20.9%) and the measured soil O₂ concentration]. An analytical solution for steady air flow from a point source in a finite, cylindrical domain is presented. The main findings are that air injection, and air extraction, are efficient at aerating the soil volume above the buried gas source or sink. On the other hand, air injection increases the aeration's effectiveness, especially below the source. Shortening the cycle period of gas injection increases gas‐use efficiency (i.e., increases the injected gas concentration) in most of the soil domain. The measurements were in good agreement with the results computed by the models’ analytical and numerical solutions.

中文翻译：

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干砂中的强迫和天然气运动–桶实验和模型

通常，对平地和扩散性气体在干燥土壤中的运动和分布的物理过程的理解和定量都很好。在这项研究中，我们推导并应用了分析和数值模型来描述在不同条件和场景下的这些过程，并在一个温度受控的实验室中在装有干燥石英砂的200-L桶中进行了气流实验。我们使用纯N ₂（0％O ₂）或大气（20.9％O ₂）从（或进入）埋入点气源（或汇）注入或抽气，以检查（a）气源深度，（b）气源排放速率和（c）注入周期对气体浓度和压力分布的影响。我们通过注入N ₂并跟踪补充的O ₂浓度[即大气（20.9％）与测得的土壤O ₂之间的差值]，进一步量化了在不同情况下从大气土壤表面扩散的贡献。浓度]。提出了一个有限的圆柱域中来自点源的稳定气流的解析解。主要发现是，空气注入和空气抽取可有效地为埋藏的气源或下沉上方的土壤体积充气。另一方面，空气注入可提高曝气效率，尤其是在空气源下方。在大多数土壤领域中，缩短注气周期可以提高气体利用效率（即增加注入的气体浓度）。测量结果与模型的解析和数值解计算的结果非常吻合。