Modeling Diffusion and Reaction in Soils: II. Atmospheric Methane Diffusion and Consumption in a Forest Soil
Modeling Diffusion and Reaction in Soils: II. Atmospheric Methane Diffusion and Consumption in a Forest Soil
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模拟土壤中的扩散和反应：II。
DOI：
10.1097/00010694-199606000-00002
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
N. Iversen
中科院分区：
文献类型：
--
作者：
C. W. Kruse;P. Møldrup;N. Iversen
研究了4~6 cm深度具有最大潜在大气甲烷消耗量的针阔混交林。用高空间分辨率测量了土壤水分、气体扩散系数和大气甲烷吸收的垂直变化，在完整的土壤岩心(2-5 cm深度间隔)。气体扩散系数随土壤水势的降低而迅速增大，气体扩散系数与土壤水分体积含量成对数关系(R2≥0.98)。在一个简单的动态扩散-反应模型中利用这一关系，模拟了完整土芯中甲烷的垂直浓度分布。该模型只考虑了甲烷在土壤空气中的扩散和甲烷消耗量随深度的变化。模拟的甲烷剖面和测量的甲烷剖面之间的良好一致性表明，甲烷在土壤空气中的扩散是控制非淹水土壤甲烷消耗的主要因素。模拟的甲烷吸收速率，通过汇总每1厘米深度的甲烷氧化计算出来的，与测量的进入土壤岩心的甲烷通量很好地吻合。模型敏感性分析表明，对甲烷最大消耗量区域及其以上的有效气体扩散系数的准确估计是真实模拟甲烷浓度分布和总吸收速率的最关键参数。
A mixed hardwood forest with a maximum potential atmospheric methane consumption at 4 to 6 cm depth was investigated. Vertical variation of soil-water content, gas diffusivity and atmospheric methane uptake was measured with high spatial resolution in intact soil cores (2-5 cm depth intervals). Gas diffusivity increased rapidly with decreasing soil-water potential and a linear relationship between gas diffusivity, and the logarithm to the volumetric soil-water content was found (R 2 ≥ 0.98). Using this relationship in a simple, dynamic diffusion-reaction model, the vertical methane concentration profiles in intact soil cores were simulated. Only diffusion of methane in the soil air and variable methane consumption with depth was considered in the model. An excellent agreement between simulated and measured methane profiles indicated that a main control of methane consumption in non-waterlogged soils is methane diffusion in the soil air. Simulated methane uptake rates, calculated by summing up the methane oxidation at each 1-cm-depth interval, agreed well with measured methane fluxes into the soil cores. Model sensitivity analyses showed an accurate estimation of the effective gas diffusion coefficient at and above the zone of maximum methane consumption to be the most critical parameter for a realistic simulation of methane concentration profiles and total uptake rates.