Use of NMR relaxation times to differentiate mobile and immobile pore fractions in a wetland soil

Abstract

Abstract. A method is presented that makes use of nuclear magnetic resonance (NMR) measurements to differentiate between mobile and immobile pore fractions in an organic peat specimen. The method is based on the T• relaxation mechanism and uses a paramagnetic reagent to mark the effective (mobile) pore space in the specimen under examination. A setup has been developed that allows controlled fluid flow through an NMR specimen while it is positioned in a magnet. Results from tests using fluid-filled glass tubes illustrate the application of the method and verify its accuracy. Results from a test using a peat moss specimen demonstrate the use of the method during a flow experiment in a wetland soil.

Modelling the effect of aggregates on N<sub>2</sub>O emission from denitrification in an agricultural peat soil

“…This fraction can be determined experimentally with nuclear magnetic resonance measurements (Culligan et al, 2001), curve fitting of measured soil water content (Price and Whittington, 2010), 2-D image analysis with resin impregnation (Hoag and Price, 1997), or 3-D X-ray tomographic image analysis (Quinton et al, 2009). In these studies the maximum immobile soil fraction for peat was determined, ranging from 0.22-0.84.…”

The effect of aggregates on N<sub>2</sub>O emission from denitrification in an agricultural peat soil

“…The mobile-immobile model has three new input parameters to describe the soil structure: the maximum immobile soil fraction of the immobile zone, F im,max , shape factor β and the half width of the aggregate a. F im,max is equal to the fraction of stagnant water in a saturated soil. Literature shows that in experimental studies this fraction in peat can be determined with nuclear magnetic resonance measurements (Culligan et al, 2001), curve fitting of measured soil water content (Price and Whittington, 2010), 2-D image analysis with resin impregnation (Hoag and Price, 1997), or 3-D X-ray tomographic image analysis (Quinton et al, 2009). In these studies values for the inactive pore fraction in peat range from 0.22-0.84.…”

Nuclear Magnetic Resonance Analysis of Natural Organic Matter

“…Many of these techniques have not been exhaustively applied to the study of NOM -contaminant interactions, and there is great potential for future studies. This said, numerous excellent studies have been carried out to study NOM interactions Lindqvis, 1969, 1971 ;Lindqvis and Lindman, 1970 ;Andrasko et al, 1972 ;Chien et al, 1997 ;Jayasundera et al, 1997 ;Nanny et al, 1997 ;Carper, 1999 ;Culligan et al, 2001 ;Nanny and Maza, 2001 ;Otto et al, 2001a ;Wang et al, 2003 ;Jaeger et al, 2006 ;Smernik, 2006 ). Combined, these studies have utilized relaxation to provide qualitative and quantitative information regarding the interactions of a range of organic contaminants in the presence of humic and fulvic acid.…”