Relationship Between Solute Diffusion Coefficient and Electrical Conductivity Under Extremely Low Soil Water Conditions
Relationship Between Solute Diffusion Coefficient and Electrical Conductivity Under Extremely Low Soil Water Conditions
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极低土壤水分条件下溶质扩散系数与电导率的关系
DOI：
10.1007/s42729-022-00792-1
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发表时间：
2022
影响因子：
3.9
通讯作者：
Sho Shiozawa
中科院分区：
文献类型：
--
作者：
Katori Miyasaka;Sho Shiozawa
溶质在土壤中的相对扩散系数（Dr）与土壤体积含水量（θ）的n次方成正比，其中θ是一个经验参数，通常在1和2之间。在低-θ时，θ与Dr的关系存在一个断点（θbr），当θ<θbr时，n的值约为4。这种变化可归因于多种机制，包括脱水引起的孔隙液态水几何分布的急剧变化。然而，由于直接Dr测量需要相当长的时间才能在低θ下提供足够的数据，很少有研究测量了Dr θ<θbr，并且在θ<θ br时Dr与θ之间的关系仍然不清楚。在这项研究中，我们研究了间接DR测量方法是否可以应用于θ<θbr的低θ区。采用一种间接测定土壤电导率的方法。利用已证实存在θ br的沙丘砂，根据EC测量值计算了从高到低θ的Dr，并与直接测量的Dr进行了比较。用EC法和瞬态法计算出的θ与Dr的关系基本一致，当θ<θbr时，Dr可由EC七计算出。结果表明，间接测量法可用于θ<θbr的低θ区。
The relative diffusion coefficient (Dr) of solutes in soils is directly proportional to the “nth” power of the volumetric soil water content (θ), wherenis an empirical parameter, which normally ranges between 1 and 2. The existence of a breakpoint (θbr) in the relationship betweenθandDrhas been demonstrated at low-θ, in which the value ofnbecomes approximately 4 whenθ<θbr. The change inncan be attributed to various mechanisms, including drastic changes in the geometrical distribution of pore liquid water caused by dehydration. However, as directDrmeasurements require considerable time to render sufficient data at low-θ, few studies have measuredDratθ<θbr, and the relationship betweenDrandθatθ<θbrremains unclear. In this study, we investigated if the indirectDrmeasurement method can be applied in the low-θregion ofθ<θbr. An indirect method for measuringDrwas employed to determine the soil electrical conductivity (ECs). Using dune sands in which the presence ofθbrwas confirmed,Drfrom high- to low-θwas calculated based on ECsmeasurements and compared with directly measuredDr. The relationships betweenθandDrcalculated based on ECsand using the transient state method were almost the same.Drcould be calculated from ECseven atθ<θbr. The results confirmed that the indirect Dr measurement method can be applied for the low-θregion ofθ<θbr.