Determination of quantitative pore‐size distribution of soils with 1H NMR relaxometry
Determination of quantitative pore‐size distribution of soils with 1H NMR relaxometry
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DOI：
10.1111/ejss.12548
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发表时间：
2018-05
影响因子：
4.2
通讯作者：
M. Meyer;C. Buchmann;G. Schaumann
中科院分区：
文献类型：
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作者：
M. Meyer;C. Buchmann;G. Schaumann
用常规方法测定土壤中的孔径分布(PSD)既费时又费力。因此，最近人们进行了几次尝试，以评估和实施质子核磁共振弛豫法(1H核磁共振弛豫法)来定量测定PSD。~1H核磁共振弛豫法不仅省时省力，而且为估计孔径、更好地分辨结果和无损测量提供了更宽的范围。为了评估这些可能性，我们测试了从七个土壤样本中得出的用于估计土壤表面松弛系数的单一校准曲线可以应用于未知土壤的程度。为了验证，利用该校正曲线根据饱和水样品的核磁共振弛豫时间分布确定了另外7个土壤样品的定量PSD，并与它们的经典水分保持曲线(WRC)进行了比较。总体而言，用这种方法确定的定量PSD很好地描述了经典的WRC。砂质、粉质和壤质土壤效果最好。差异最大的是粘粒含量较大(47%)和有机质含量(10%和21%)的土壤。我们的结果表明，这些差异源于膨胀过程。
The determination of pore‐size distribution (PSD) in soil by conventional methods can be time‐ and effort‐consuming. Therefore, several attempts have been made recently to assess and implement proton nuclear magnetic resonance relaxometry (1H NMR relaxometry) to determine PSDs quantitatively. The 1H NMR relaxometry promises not only to be more time‐ and effort‐saving but also offers a broader range for the estimation of pore size, better resolved results and non‐destructive measurements. To evaluate these possibilities, we tested the extent to which a single calibration curve for the estimation of surface relaxivity of soil, derived from seven soil samples, can be applied to unknown soils. For validation, the quantitative PSDs of seven additional soil samples were determined from the distributions of NMR relaxation times of water saturated samples using this calibration curve; they were compared with their classical water retention curves (WRCs). In general, the quantitative PSDs determined by this approach described the classical WRCs quite well. The best results were obtained for sandy, silty and loam soils. The largest differences were for soils with large clay (47%) and SOM contents (10 and 21%). Our results suggest that these differences derive from swelling processes.