Variations in pore distribution of reconstructed soils induced by opencast mining and land rehabilitation based on computed tomography images

Opencast coal mining is an anthropogenic activity that changes the antecedent soil profile, and it was important to understand the distribution characteristics of soil pore and then select suitable land rehabilitation measures. To better quantify the pore distribution characterization of reconstructed soils in opencast coalmine dumps, high-resolution and non-destructive computed tomography (CT) method was used to study the effect of opencast coal-mining and land rehabilitation on the soil pore distribution by scanning soils from the Antaibao Opencast Coal-mine in China. The soils were taken from the dump platforms with different rehabilitation time and an unmined site. ImangeJ 2 was used to process the scanned images and the soil pore densities and porosities of different pore sizes were used to analyze the distribution characteristics of soil pore. Opencast mining activities decreased soil pore density and soil porosity, especially in macropores. Compared to unmined soils, the total porosity of the non-rehabilitated soils reduced by 25.0%, 20.5%, 17.7% at the depths of 0–25, 25–50, 50–75 cm, respectively. Vegetation rehabilitation should be used to develop soil pore structure and improve the proportion of different pore sizes.