Spatial characterization of iron oxides in hydric mineral soils

位于地下水位接近地表的土壤，以及在局部洼地发现的土壤，经常经历长期或相对永久的涝灾。积水减缓了氧气向土壤中的扩散；这很快导致厌氧条件，因为微生物继续呼吸有机物质（主要来自植被）。在这种土壤中，铁的溶解度可以通过化学还原而成倍地增加——这一过程被称为“蚀变”。闪灰不仅改变了这些土壤的颜色（从黄红色变为灰蓝色），还可能影响结构稳定性、养分和污染物在土壤中的流动，以及微生物产生的温室气体（如氨和甲烷）。目前的研究重点是利用高分辨率CT扫描仪来了解这种元素在局部化学过程中的作用。本研究的第二个组成部分将评估铁的分布（由CT扫描确定）对土壤磁化率的影响。这将有助于了解磁化率的实地测量，这种技术已被提议作为划定有斜面的土壤以进行特定地点管理的手段。

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.