New Perspectives for the Application of High-Resolution Benchtop X-Ray MicroCT for Quantifying Void, Solid and Liquid Phases in Soils

Abstract

Recent technological advances of imaging techniques such as X-ray computed tomography (CT) provide powerful means for visualization of the soil interior to evaluate pore topological properties and structure and study dynamic processes in a noninvasive way. The objective of this chapter is to present new opportunities for the application of advanced benchtop X-ray MicroCT scanners in soil science and vadose zone research and to discuss advantages and limitations associated with the MicroCT technique. Instrumentation, spatial resolution, image contrast and other aspects that directly affect the ability to discriminate and quantify various soil phases are discussed. Analysis of nearly 400 published papers regar- ding the application of computed tomography in soil and porous media research indicate a surge of applications of benchtop MicroCT systems over the last few years. These instruments are becoming more affordable and popular and have great potential to significantly enhance the ability to characterize and better understand dynamic processes in soils and provide important insights for the development of advanced mathematical pore network and fluid dynamics models. New advanced benchtop MicroCT systems are very flexible in terms of sample size and image spatial resolution and provide high quality images, comparable to advanced syn- chrotron systems. Results of soil samples scanned at different spatial resolutions are presented and their air phase (porosity) and solid phase are evaluated and quantified. Examples of liquid phase quantification using sodium iodide as dopant are also presented for glass bead and undisturbed soil samples. C.M.P.