Details
| Original language | English |
|---|---|
| Pages (from-to) | 50-63 |
| Number of pages | 14 |
| Journal | Journal of Hydrology and Hydromechanics |
| Volume | 61 |
| Issue number | 1 |
| Publication status | Published - Mar 2013 |
Abstract
Focusing on the idea that multivalent cations affect SOM matrix and surface, we treated peat and soil samples by solutions of NaCl, CaCl2 or AlCl3. Water binding was characterized with low field 1H-NMR-relaxometry (20 MHz) and 1H wideline NMR spectroscopy (400 MHz) and compared to contact angles. From 1H wideline, we distinguished mobile water and water involved in water molecule bridges (WaMB). Large part of cation bridges (CaB) between SOM functional groups are associated with WaMB. Unexpectedly, 1H NMRrelaxometry relaxation rates suggest that cross-linking in the Al-containing peat is not stronger than that by Ca. The relation between percentage of mobile water and WaMB water in the context of wettability and 1H NMR relaxation times confirms that wettability controls the water film surrounding soil particles. Wettability is controlled by WaMB-CaB associations fixing hydrophilic functional groups in the SOM interior. This can lead to severe water repellency. Wettability decreases with increasing involvement of functional groups in CaB-WaMB associations. The results demonstrate the relevance of CaB and WaMB for the dynamics of biogeochemical and hydrological processes under field conditions, as only a few percent of organic matter can affect the physical, chemical, and biological functioning of the entire 3-phase ecosystem.
Keywords
- 1H wideline NMR spectroscopy, Cation bridges, Contact angle, Low field 1H NMR relaxometry, Soil organic matter (SOM), Water molecule bridges
ASJC Scopus subject areas
- Environmental Science(all)
- Water Science and Technology
- Engineering(all)
- Mechanical Engineering
- Chemical Engineering(all)
- Fluid Flow and Transfer Processes
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In: Journal of Hydrology and Hydromechanics, Vol. 61, No. 1, 03.2013, p. 50-63.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Combined proton NMR wideline and NMR relaxometry to study SOM-water interactions of cation-treated soils
AU - Schaumann, Gabriele E.
AU - Diehl, Dörte
AU - Bertmer, Marko
AU - Jaeger, Alexander
AU - Conte, Pellegrino
AU - Alonzo, Giuseppe
AU - Bachmann, Jörg
N1 - Copyright: Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/3
Y1 - 2013/3
N2 - Focusing on the idea that multivalent cations affect SOM matrix and surface, we treated peat and soil samples by solutions of NaCl, CaCl2 or AlCl3. Water binding was characterized with low field 1H-NMR-relaxometry (20 MHz) and 1H wideline NMR spectroscopy (400 MHz) and compared to contact angles. From 1H wideline, we distinguished mobile water and water involved in water molecule bridges (WaMB). Large part of cation bridges (CaB) between SOM functional groups are associated with WaMB. Unexpectedly, 1H NMRrelaxometry relaxation rates suggest that cross-linking in the Al-containing peat is not stronger than that by Ca. The relation between percentage of mobile water and WaMB water in the context of wettability and 1H NMR relaxation times confirms that wettability controls the water film surrounding soil particles. Wettability is controlled by WaMB-CaB associations fixing hydrophilic functional groups in the SOM interior. This can lead to severe water repellency. Wettability decreases with increasing involvement of functional groups in CaB-WaMB associations. The results demonstrate the relevance of CaB and WaMB for the dynamics of biogeochemical and hydrological processes under field conditions, as only a few percent of organic matter can affect the physical, chemical, and biological functioning of the entire 3-phase ecosystem.
AB - Focusing on the idea that multivalent cations affect SOM matrix and surface, we treated peat and soil samples by solutions of NaCl, CaCl2 or AlCl3. Water binding was characterized with low field 1H-NMR-relaxometry (20 MHz) and 1H wideline NMR spectroscopy (400 MHz) and compared to contact angles. From 1H wideline, we distinguished mobile water and water involved in water molecule bridges (WaMB). Large part of cation bridges (CaB) between SOM functional groups are associated with WaMB. Unexpectedly, 1H NMRrelaxometry relaxation rates suggest that cross-linking in the Al-containing peat is not stronger than that by Ca. The relation between percentage of mobile water and WaMB water in the context of wettability and 1H NMR relaxation times confirms that wettability controls the water film surrounding soil particles. Wettability is controlled by WaMB-CaB associations fixing hydrophilic functional groups in the SOM interior. This can lead to severe water repellency. Wettability decreases with increasing involvement of functional groups in CaB-WaMB associations. The results demonstrate the relevance of CaB and WaMB for the dynamics of biogeochemical and hydrological processes under field conditions, as only a few percent of organic matter can affect the physical, chemical, and biological functioning of the entire 3-phase ecosystem.
KW - 1H wideline NMR spectroscopy
KW - Cation bridges
KW - Contact angle
KW - Low field 1H NMR relaxometry
KW - Soil organic matter (SOM)
KW - Water molecule bridges
UR - http://www.scopus.com/inward/record.url?scp=84875469043&partnerID=8YFLogxK
U2 - 10.2478/johh-2013-0007
DO - 10.2478/johh-2013-0007
M3 - Article
AN - SCOPUS:84875469043
VL - 61
SP - 50
EP - 63
JO - Journal of Hydrology and Hydromechanics
JF - Journal of Hydrology and Hydromechanics
SN - 0042-790X
IS - 1
ER -