Journal Article

FZJ-2016-06119

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Drying of a Natural Soil Under Evaporative Conditions: A Comparison of Different Magnetic Resonance Methods

Merz, S. (Corresponding author)FZJ* ; Pohlmeier, A.FZJ* ; Balcom, B. J. ; Enjilela, R. ; Vereecken, H.FZJ*

2016
Springer Wien [u.a.]

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Please use a persistent id in citations: doi:10.1007/s00723-015-0736-6

Abstract: Soils are highly complex and heterogeneous porous materials, and thus measuring water distribution non-invasively with high accuracy and adequate spatial resolution still remains challenging. The first few centimeters of a soil surface control the vapor flux to the atmosphere justifying the need for high spatial resolution measurements of moisture content. The objective of this study was to compare and assess the feasibility of various high-resolution magnetic resonance (MR) methods to characterize an unsaturated porous system. We employed (1) a spin-echo, (2) three types of single-point imaging and (3) a unilateral three-magnet array to monitor T1 and T2,app relaxation time spectra and the effective moisture saturation (ΘMR) of a silt loam under progressing desaturation with focus on an emerging unsaturated surface layer, which is predicted by theory. During the first stage of drying where evaporation occurred at the soil surface, all methods showed homogeneously distributed moisture. A decreasing ΘMR and a shift in the T1 and T2,app relaxation time spectra to shorter values indicated the commencement of stage 2 evaporation coincided with an increasing unsaturated layer. At low water contents, the most suitable method to determine the extent of a desaturated surface zone with high accuracy was found to be single--point ramped imaging with T1 enhancement. As a simple and low-cost device the unilateral three-magnet array was feasible to monitor the drying process until the dry surface layer developed.

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Contributing Institute(s):

1. Agrosphäre (IBG-3)

Research Program(s):

1. 255 - Terrestrial Systems: From Observation to Prediction (POF3-255) (POF3-255)

Appears in the scientific report 2016

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; No Authors Fulltext ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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