X-ray microtomography analysis of urban soils of the Rostov region

Urban soils are exposed to transformations of physical properties which are not captured by the conventional approaches due to the presence of impurities that can distort the obtained data. Advanced visualization techniques such as X-ray computed tomography (CT) offer new opportunities of exploring heterogeneity of soil properties at horizon or aggregate scales. The studies of the structure and pore space of different types of urban soils formed on chernozems were carried out using a SkyScan 1172G tomograph. The tomographic study was carried out in the humus-accumulative horizons for six main types of urban soils. The volumetric parameters for the pore space were calculated, and pores orientation and shape parameters were calculated in 2D sections. The closed pore value was obtained as the most informative diagnostic indicator of the urban soils structural condition. A morphometric analysis of the shape and orientation of fine soil macropores with a diameter of 0.3–2.0 mm also showed significant structural differences between natural soils under woody or grassy vegetation and urban anthropogenically transformed soils. All studied soils at the aggregate scales slightly differ from each other in the value of the internal aggregate tomographic porosity. This shows that the compaction because of anthropogenic transformation occurs due to the interaggregate pore space. At the aggregate porous spaces, no changes can be traced.