Quantitative mapping of solute accumulation in a soil‐root system by magnetic resonance imaging. Issue 8 (4th August 2017)

• Record Type: Journal Article
• Authors: Haber‐Pohlmeier, S.; Vanderborght, J.; Pohlmeier, A.
• Is Part Of: Water resources research. Volume 53:Issue 8(2017)
• Page Start: 7469
• Page End: 7480
• Publication Date: 2017-08-04
• Subjects: magnetic resonance imaging -- tracer quantification -- GdDTPA2 -- soil water -- white lupin -- roots; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2017WR020832
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Differential uptake of water and solutes by plant roots generates heterogeneous concentration distributions in soils. Noninvasive observations of root system architecture and concentration patterns therefore provide information about root water and solute uptake. We present the application of magnetic resonance imaging (MRI) to image and monitor root architecture and the distribution of a tracer, GdDTPA 2− (Gadolinium‐diethylenetriaminepentacetate) noninvasively during an infiltration experiment in a soil column planted with white lupin. We show that inversion recovery preparation within the MRI imaging sequence can quantitatively map concentrations of a tracer in a complex root‐soil system. Instead of a simple T 1 weighting, the procedure is extended by a wide range of inversion times to precisely map T 1 and subsequently to cover a much broader concentration range of the solute. The derived concentrations patterns were consistent with mass balances and showed that the GdDTPA 2− tracer represents a solute that is excluded by roots. Monitoring and imaging the accumulation of the tracer in the root zone therefore offers the potential to determine where and by which roots water is taken up. Key Points: Longitudinal relaxation time maps allow the quantification of a contrast agent in natural porous media over a wide concentration range GdDTPA is a convenient tracer for monitoring flow and for quantification of accumulation processes in a lupin root soil system Active and less‐active roots can be discriminated