Abstract:
Coal mining leads to land subsidence in mining areas with high underground water levels, resulting in changes in soil structure and degradation of soil fertility. Filling reclamation is commonly used to restore subsided land. To compare the effectiveness of different filling reclamation materials on the restoration of soil organic carbon in mining areas, this study focuses on Yellow River sand reclamation (RSR), guest soil reclamation (GSR), lake mud reclamation (LMR), and coal gangue reclamation (CGR) sites in high underground water level mining areas of Jining City, Shandong Province. Soil samples from 0−20, 20−40, 40−60 cm depths were collected from both the reclaimed land and surrounding normal farmland. The vertical distribution characteristics and sensitivity of SOC and its components-dissolved organic carbon (DOC), microbial biomass carbon (MBC), readily oxidizable organic carbon (ROC), humic acid carbon (HAC), light fraction carbon (LFC), and particulate organic carbon (POC)-in different reclamation filling soils were studied. The results indicated that: The components of soil organic carbon in soils reclaimed with different filling materials exhibit significant surface aggregation. LFC is most sensitive to LMR and CGR, HAC is most sensitive to GSR, and ROC is most sensitive to RSR. GSR positively affect the POC and DOC contents of reclaimed soil, LMR positively affect the MBC, LFC, and POC contents of reclaimed soil, and CGR positively affect the MBC content of reclaimed soil. The various components of soil organic carbon in soils reclaimed with different filling materials show highly significant positive correlations with each other (
p < 0.01). They also exhibit significant or highly significant positive correlations with soil Availabe Nitrogen (AN), Available Phosphorus (AP), and Available Potassium (AK) contents and significant or highly significant negative correlations with soil Bulk Density (
BD). A comprehensive comparison indicates that in high groundwater level mining areas, the restoration effects of four backfill materials on soil organic carbon and its components follow the order: LMR > GSR > RSR > CGR.