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- Title
Effects of Soil Solution's Constituents on Proton NMR Relaxometry of Soil Samples.
- Authors
Jaeger, Fabian; Rudolph, Nicole; Lang, Friederike; Schaumann, Gabriele E.
- Abstract
Proton nuclear magnetic resonance (`H NMR) relaxometryas been used to analyze pore size distributions of wet porous samples. To make this method applicable to soil samples, knowledge about contribution from the soil solution to the total proton relaxation is needed. We extracted soil solutions from nine soil samples and determined transverse proton relaxation rates, the concentration of Fe, Mn, and total organic C (TOC), and the pH of the solutions. The effects of Fe, Mn, and TOC on the proton relaxation in the soil solution were compared with those of dissolved Fe2~, Fe3~, and Mn2~ an~l of glucose, D-cellobiose, potassium hydrogen phthalate, sodium alginate, and agar in model solutions. Proton relaxation rates in the soil solutions were up to 20 times larger than in pure water, which was mainly due to dissolved Fe(IIl) and Mn(I1) species. The relaxivities of Fe and Mn in soil solution were reduced to 40 and 70% compared with Fe(lII) and M~(II) in a model solution, respectively. Smaller relaxivities were primarily due to the format~on of metal-organic complexes. We conclude that the proton relaxation in soil samples is generally accelerated by the soil solution, and its contribution must be considered to estimate pore sizes from relaxation times. By using the calculated relaxivities of Fe and Mn in soil solution, the contribution of the soil solution to the total proton relaxation can be estimated from the Fe and Mn concentration in the soil solution. Abbreviations: CPMG, Carr-Purcell-Mciboom-Gill; DOM, dissolved organic matter; NICA, nonideal consistent competitive adsorption; NMR, nuclear magnetic resonance; TOG, total organic carbon.
- Subjects
SOIL solutions; NUCLEAR magnetic resonance; PROTONS; SOIL moisture; ORGANIC compounds; IRON; SOILS
- Publication
Soil Science Society of America Journal, 2008, Vol 72, Issue 6, p1694
- ISSN
0361-5995
- Publication type
Article
- DOI
10.2136/sssaj2007.0427