Spatial characterization of iron oxides in hydric mineral soils

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Soils located in landscapes with near-surface groundwater tables, as well as those found in localized depressions, frequently experience prolonged or relatively permanent periods of water logging. Water logging slows the diffusion of oxygen into the soil; this quickly leads to anaerobic conditions, as the micro-organisms continue to respire organic matter (originating primarily from vegetation). In such soils the solubility of iron may be increased manifold by chemical reduction - this process is called 'gleying'. Gleying not only changes the colour of these soils (from yellow-red to gray-blue), it may also influence structural stability, the movement of nutrients and pollutants through the soil, as well as the microbial production of greenhouse gases (such as ammonia and methane). The current research is focused on the utilization of a high-resolution CT scanner to understand the role of this element in local chemical processes. The second component of this research will evaluate the effect of the distribution of iron (as determined by CT scanning) on soil magnetic susceptibility. This will be useful for understanding field measurements of magnetic susceptibility, a technique that has been proposed as a means of delineating gleyed soils for site-specific management.