Environmental NMR: Magnetic Resonance Imaging

Nestle, Nikolaus; Morris, Robert H.; Baumann, Thomas

doi:10.1002/9780470034590.emrstm1349

Cited by 4 publications

(3 citation statements)

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“…Since MR was first used for the determination of soil moisture by Andreev and Martens (1960), the technique and associated methods have undergone constant improvement, and MR has become a versatile toolkit in the field of environmental science (Nestle et al, 2007), particularly for porous media research (Koptyug, 2012). Magnetic resonance is preferred over other methods used for monitoring moisture because it is noninvasive and provides information on the environment of the water and insights into the diffusion pathways of water molecules in a probed volume (Korb, 2011; Watson and Chang, 1997).…”

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confidence: 99%

Magnetic Resonance Monitoring and Numerical Modeling of Soil Moisture during Evaporation

Merz

Balcom

Enjilela

et al. 2018

Vadose Zone Journal

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Evaporation from bare soil surfaces can be restrained to a great extent with the development of a dry layer at the soil surface where capillary hydraulic conductance ceases and water flow proceeds only by gas phase transport. Model calculations and preliminary experiments with model porous media have shown that this surface layer can be very thin. An accurate characterization of these processes is required, which is provided by noninvasive magnetic resonance (MR) methods. The evaporative drying of a silt loam and a sandy loam was monitored at high spatial resolution in laboratory experiments. The MR data were used to assess the performance of two numerical models: (i) the Richards equation, which considers isothermal liquid water flow, and (ii) a coupled soil water, heat, and vapor flow numerical model. The experimental results reveal two distinct drying regimes for both soil types where, at the onset of the second evaporation stage, a dry surface zone developed with increasing thickness over time. This layer revealed that water loss inside the soil coincided with a relatively low evaporation rate as the liquid continuity to the soil surface vanished. The modeling results clearly demonstrated the need to consider heat and vapor flow. It was shown, as a proof of principle, that MR relaxation time spectra may serve as a proxy to follow desaturation processes where spatially resolved transverse relaxation can reveal a secondary evaporation front.

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confidence: 99%

Magnetic Resonance Monitoring and Numerical Modeling of Soil Moisture during Evaporation

Merz

Balcom

Enjilela

et al. 2018

Vadose Zone Journal

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“…However, a more comprehensive overview is found in Simpson et al 9 or Simpson and Simpson 10 with more specific literature focusing on various subareas, namely, solution-state, 2 highresolution-magic angle spinning (HR-MAS) (sometimes termed gel-state NMR), 11,12 solid-state NMR, 13−15 low-field NMR, 16,17 and imaging. 18 Table 1 summarizes some of the main NMR techniques used in environmental research and provides some basic information that may be useful to nonexperts wishing to perform environmental NMR studies. Readers should note that most of these experiments are applicable to any NMR active nuclei with 1 H, 2 H, 7 Li, 13 C, 14 N 15 N, 19 F, 27 Al, 29 Si, 31 P, 111 Cd, 113 Cd, 195 Pt, 199 Hg, 207 Hg, being among the most sensitive and environmentally relevant nuclei.…”

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confidence: 99%

“…An overview of the most common forms of experiments and techniques, used in environmental applications are summarized in Tables and . However, a more comprehensive overview is found in Simpson et al or Simpson and Simpson with more specific literature focusing on various subareas, namely, solution-state, high-resolution-magic angle spinning (HR-MAS) (sometimes termed gel-state NMR), , solid-state NMR, − low-field NMR, , and imaging Table summarizes some of the main NMR techniques used in environmental research and provides some basic information that may be useful to nonexperts wishing to perform environmental NMR studies.…”

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Environmental Nuclear Magnetic Resonance Spectroscopy: An Overview and a Primer

Simpson

Soong

2017

Anal. Chem.

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NMR spectroscopy is a versatile tool for the study of structure and interactions in environmental media such as air, soil, and water as well as monitoring the metabolic responses of living organisms to an ever changing environment. Part review, part perspective, and part tutorial, this Feature is aimed at nonspecialists who are interested in learning more about the potential and impact of NMR spectroscopy in environmental research.

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