Integrating physical and chemical techniques to characterise soil microsites

Many problems in environmental and soil research require techniques that quantify the soil microenvironment. It has become increasingly apparent that we need novel micro-analytical techniques to compliment well established methods that study soils at macro-spatial scales. Despite tremendous progress in this field over the last decade, quantitative methods have developed within separate disciplines and operate at different spatial scales hampering their integration. Moreover, it means that opportunities to integrate these methods may be overlooked. In this paper we develop methods that enable integration of a 3-D non-invasive technique to characterise soil structure (X-ray CT) with a 2-D spectroscopic method that characterises the spatial distribution of chemical elements on surfaces (SEM-EDX). First we developed statistical software to locate the 2-D plane in which SEM-EDX analyses were performed within the 3-D volume. Then we demonstrate that selected compounds, including particulate sources of C and CaCO3, can be quantified with SEM-EDX and subsequently visualized within the 3-D soil environment. Finally, we demonstrated that when we characterized sequential slices with SEM-EDX we could use co-kriging methods to predict the 3-D spatial distribution of chemical elements. We discuss the possibilities and problems that need to be resolved to combine these methods.