Determination of the gas diffusion coefficient of a peat grassland soil
Determination of the gas diffusion coefficient of a peat grassland soil
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DOI：
10.1111/ejss.12056
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发表时间：
2013-10
影响因子：
4.2
通讯作者：
A. Boon;J. S. Robinson;P. Nightingale;L. Cárdenas;D. Chadwick;A. Verhoef
中科院分区：
文献类型：
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作者：
A. Boon;J. S. Robinson;P. Nightingale;L. Cárdenas;D. Chadwick;A. Verhoef
泥炭地栖息地是重要的碳库，也有可能成为温室气体的重要来源，特别是当受到人工排水和化肥使用等变化的影响时。旨在估计泥炭地温室气体排放的模型需要准确估计气体在土壤中传输的扩散系数(D)。目前对泥炭地土壤的具体测量是有限的。这项研究测量了泥炭土壤上覆粘土层的D值，并与广泛使用的模型的值进行了比较。为了比较，测定了砂壤土参照土的Ds值。用Currie(1960年)的方法测量了充气孔隙度(ϵ)范围为0到0.5cm3 cm−3之间的Ds值。泥炭岩心的Ds值在3.2x10−4和4.4x10−3m2小时−1之间，壤质粘土岩心的Ds值在0和4.7×10−3m2小时−1之间，砂质参考土壤的Ds值在5.4x10−4和3.4x10−3m2小时−1之间。自由空气扩散系数随土壤类型的不同而不同；然而，Campbell(1985)模型对所有土壤的测量值提供了最好的重复性。因此，这项研究表明，在研究土壤没有准确测量的D和孔隙度值的情况下，使用Campbell模型是合适的。未来研究减少测量期间泥炭收缩的方法，从而允许测量更大范围的ϵ的DS将是有益的。
Peatland habitats are important carbon stocks that also have the potential to be significant sources of greenhouse gases, particularly when subject to changes such as artificial drainage and application of fertilizer. Models aiming to estimate greenhouse gas release from peatlands require an accurate estimate of the diffusion coefficient of gas transport through soil (Ds). The availability of specific measurements for peatland soils is currently limited. This study measured Ds for a peat soil with an overlying clay horizon and compared values with those from widely available models. The Ds value of a sandy loam reference soil was measured for comparison. Using the Currie (1960) method, Ds was measured between an air‐filled porosity (ϵ) range of 0 and 0.5 cm3 cm−3. Values of Ds for the peat cores ranged between 3.2 × 10−4 and 4.4 × 10−3 m2 hour−1, for loamy clay cores between 0 and 4.7 × 10−3 m2 hour−1 and for the sandy reference soil they were between 5.4 × 10−4 and 3.4 × 10−3 m2 hour−1. The agreement of measured and modelled values of relative diffusivity (Ds/D0, with D0 the diffusion coefficient through free air) varied with soil type; however, the Campbell (1985) model provided the best replication of measured values for all soils. This research therefore suggests that the use of the Campbell model in the absence of accurately measured Ds and porosity values for a study soil would be appropriate. Future research into methods to reduce shrinkage of peat during measurement and therefore allow measurement of Ds for a greater range of ϵ would be beneficial.