Detection of soil physical properties of reclaimed land in open-pit mining area: feasibility of application of ground penetrating radar.

In order to obtain the typical soil physical properties of reclaimed land more quickly and accurately, the South Dump of the China Coal's Antaibao Open-Pit Mine in Pingshuo was focussed on in this paper, and ground penetrating radar (GPR) technology was utilized to detect the soil physical properties of reclaimed land in the mining area. The soil profile sampling and GPR detection methods were used to acquire the data. The gravel content of surface soil was analyzed by counting the number of isolated gravel signals in GPR images. The change of effective soil thickness was analyzed by establishing the fitting relationship between calibration depth and GPR image depth. The Topp's model was validated by comparing its inversion with the measured soil volumetric water content. And the Topp's model was further validated by the soil volumetric water content obtained from the Topp's model and which obtained from the wave velocity inversion. The results are as follows: (1) Based on the number of isolated gravel signals in GPR images, we could qualitatively analyze the gravel content of surface soil reclaimed in the mining area. As the number of isolated gravel signals was greater, the gravel content of the surface soil was higher. (2) Using the known relative permittivity, electromagnetic wave velocity, and soil volumetric water content, the calibration depth and the reflection depth of the target (calibrator) of the GPR images were segmented, and the correlation between them is high. The fitting relationship (R2) of each segment was higher than 0.940, and the average value of the five-segment R2 was 0.966, which indicated more accurate detection of the effective soil thickness of the reclaimed land in the mining area. (3) GPR could be used to detect the soil volumetric water content of reclaimed land in mining area, and Topp's model was used for calculation of soil volumetric water content. The average deviation rate between the values from Topp's model and the measured values was 12%, and the average absolute value of the difference was 2%. In summary, the benefits of using GPR to detect soil physical properties of reclaimed land in mining area are as follows: (1) GPR can be used to detect soil layer thickness and surface gravel content faster and more accurately. (2) Topp model can also be used to calculate the soil moisture content of non-natural deposits such as reclaimed land in mining area.

Study on the variation of arable land use and management countermeasures under rapid urbanization: the application of a gravity model in a regional perspective.

Scientifically determining the characteristics of arable land use in different regions is significant in promoting arable land protection. Most studies on the changes in arable land focus on an isolated analysis of the impact of urban development on arable land. Studies on the influence mechanism of regional spatial forces in different cities from the macro perspective are limited. A gravity model and ArcGIS spatial analysis methods were used to analyze the characteristics and driving mechanisms of arable land changes in different urban function orientations from the perspective of interregional economic interaction. We hope to provide guidance for the establishment of arable land protection in a similar city circle. The results indicated the following: (1) During the study period, the geographic range of arable land with strong dynamic changes (average annual change exceeding 1.5%) gradually widened from the core area to the surrounding area, while the annual change rate decreased. (2) There is a strong correlation between the change in arable land use and the scope of gravitational action. The dynamic changes in arable land in areas with strong gravitational relationships with the core area are strong, while in the weak gravitational areas that are less affected by the core area, the average annual rate of change is nearly below 1%. (3) In the 10-year study period, the overall changing trend of the radiation circle in the core area expanded. The gravitational value where the breaking point falls within its own administrative division is more related to the change of its arable land area, and the greater the gravitational attraction is, the more likely the correlation. In a city circle, it is essential to both protect arable land resources and promote coordinated economic development. Future research on arable land utilization in different city circles should consider overall area development. Different functional areas can be determined by calculating the gravitational value, then regional development potential and key development types can be determined, and arable land protection measures can be optimized based on these functional areas.

Responses of Melilotus officinalis Growth to the Composition of Different Topsoil Substitute Materials in the Reclamation of Open-Pit Mining Grassland Area in Inner Mongolia.

The purpose of this study was to reveal that reconstructed soil composed of different types and proportions of materials has different effects on the growth of Melilotus officinalis, and to determine the most suitable formula of reconstructed soil materials to use for soil replacement. Using topsoil, coal gangue, fly ash, and rock and soil stripping materials from Shengli Mining Area of Inner Mongolia as raw materials, stratified and mixed pot experiments were carried out in a greenhouse using different proportions of each material. The differences in the aboveground biomass, leaf width, plant height, and root length of Melilotus officinalis plants in pot experiments were then compared using analysis of variance. The results showed that using different combinations of materials in different proportions affected the growth status of Melilotus officinalis, and their effects on biomass were greater than their effects on plant height, root length, and leaf width. When topsoil, coal gangue, and rock and soil stripping materials were mixed at a ratio of 3:3:4, respectively, the biomass of Melilotus officinalis increased by nearly 30% compared with that of plants potted in pure topsoil. When the content of coal gangue was controlled to be 30%, the content of fly ash was below 10%, and the content of rock and soil stripping materials was below 40%, the reconstructed soil conditions clearly promoted the growth of Melilotus officinalis. Coal gangue, rock and soil stripping materials, and fly ash can thus be used as substitutes for topsoil. Mixing soil reconstruction materials in the optimal proportion can solve the scarcity of topsoil in the grassland mining areas in the study region and, at the same time, can effectively improve the utilization of solid waste in this mining area.