[635] - A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils

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Pohlmeier, A., Haber-Pohlmeier, S., Stapf, S., 2009. A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils. Vadose Zone Journal, 8 (3), 735 - 742. DOI: 10.2136/vzj2008.0030.
Title(s):Main Title: A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils
Description(s):Abstract: This study used nuclear magnetic resonance (NMR) relaxometry at different Larmor frequencies to investigate water dynamics in the pore space of natural porous media. Spin-lattice NMR relaxation times (T 1) were determined in purified fine sand and two natural soils, Kaldenkirchen sandy loam and Merzenhausen silt loam, by means of fast field cycling relaxometry. This technique investigates relaxation processes as a function of the Larmor frequency ν in the range between 0.005 and 20 MHz, yielding so-called relaxation dispersion curves (1/T 1 vs. log ν). The data were further analyzed by means of inverse Laplace transformation to calculate the T1 relaxation time distribution functions. Only the fine sand was characterized by monomodal distribution with T 1 of about 1 s at 20 MHz, whereas the natural soil samples showed multimodal distribution functions in the range between 2 and 70 ms. With decreasing Larmor frequency, all distribution functions kept their shapes but were shifted to faster relaxation times. The corresponding relaxation dispersion curves indicate predominance of two-dimensional diffusion of water in the soils, whereas in the macroporous sand, diffusion behaved like unrestricted three-dimensional diffusion. In terms of the Brownstein–Tarr model, the decrease in the T 1 relaxation times with increasing silt and clay content can be explained by an increase of the surface/volume ratios (S/V) of these porous media, i.e., by a decrease in the pore sizes. Finally, distribution functions of the pore size parameter V/S were obtained from the spin-lattice relaxation time distributions by normalizing on the specific surface area. They ranged from submicrometers in the Merzenhausen soil to micrometers and submillimeters in the Kaldenkirchen soil and fine sand, respectively.
Identifier(s):DOI: 10.2136/vzj2008.0030
Responsible Party
Creator(s):Author: Andreas Pohlmeier
Author: Sabina Haber-Pohlmeier
Author: Siegfried Stapf
Publisher:Soil Science Society of America
TR32 Topic:Soil
Subject(s):CRC/TR32 Keywords: NMR, Soil, Soil Water Content
File Details
File Name:2009_Pohlmeier_VZJ.pdf
Data Type:Text
Size(s):8 Pages
File Size:1472 kB (1.437 MB)
Date(s):Issued: 2009-08-01
Mime Type:application/pdf
Data Format:PDF
Download Permission:OnlyTR32
General Access and Use Conditions:For internal use only
Access Limitations:For internal use only
Licence:TR32DB Data policy agreement
Measurement Region:Ellebach
Measurement Location:Merzenhausen
Specific Informations - Publication
Article Type:Journal
Source:Vadose Zone Journal
Number Of Pages:8
Page Range:735 - 742
Metadata Details
Metadata Creator:Markus Küppers
Metadata Created:2013-12-02
Metadata Last Updated:2013-12-02
Funding Phase:1
Metadata Language:English
Metadata Version:V40
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