Yuxin Tian

(1) Background: The spontaneous combustion of coal (SCC) not only consumes huge amounts of coal resources but also causes environmental degradation. Rare earth elements (REE) can be taken as an effective indicator to evaluate the environmental effects of SCC. Coal in the Rujigou Mine has been spontaneously combusting for hundreds of years. (2) Methods: The geochemical properties of REE and major elements in the soil of the Rujigou coal mine are methodically examined to reveal the environmental effects of SCC. (3) Results: Soil REE concentration in the Rujigou mine is 216.09 mg/kg, and there is an enrichment of light rare earth elements (LREE) and a depletion of heavy rare earth elements (HREE), LREE/HREE in Rujigou mine was 5.52. The spontaneous combustion of coal could change the vertical distribution of REE, which is conducive to the enrichment of LREE. According to the Eu anomaly and δCe/δEu, the source of material in this mine may be derived from the terrigenous clastic rock controlled by weak reduction. Aluminum and titanium have similar geochemical behavior to REE, especially LREE. The concentration of sulfur is negatively correlated with REE, especially HREE. Calcium, sodium, and magnesium all had a negative correlation with LREE. (4) Conclusions: The spontaneous combustion of coal can lead to the fractionation of light and heavy rare earth elements, resulting in the enrichment of LREE and depletion of HREE.

Ground deformation poses an imminent threat to urban development. This study uses the multiscale geographically weighted regression (MGWR) model to investigate the spatial heterogeneity in factors influencing ground deformation, thereby elucidating the drivers behind regional variations in ground deformation patterns. To gain insights into the characteristics of ground deformation in Zhuhai, China, and its spatial relationship with natural and anthropogenic features, we initially utilized the small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) method to collect data on ground deformation and its distribution across the entire area. Concurrently, remote sensing imagery was used to identify the various mechanisms affecting ground deformation during the same period, including geotectonic conditions, geographic environment, and human activities. Subsequently, we used the MGWR model to quantitatively estimate the effects of these driving force factors on ground deformation in Zhuhai. Our findings reveal significant ground deformation in specific areas, including Baijiao Town (Doumen District), Hongqi Town (Jinwan District), the Gaolan Port Economic Zone, and the northern part of Hengqin Town, with peak deformation rates reaching 117 mm/y. Key drivers of ground deformation in Zhuhai include NDVI, groundwater extraction intensity, and soft soil thickness. The application of the MGWR model, with an R-sq value of 0.910, outperformed both the global regression model ordinary least squares (OLS), with an R-sq value of 0.722, and the local regression model geographically weighted regression (GWR), with an R-sq value of 0.770, in identifying driving forces. This study can provide valuable insights for government policies aimed at mitigating the disaster risks associated with urban ground deformation.