The alterations in soil organic carbon transformation and bacterial community structure in mining areas induced by coal dust of different coalification degrees

Purpose In coal mining regions, soil organic carbon content is elevated by the deposition of coal dust through natural settling and transportation. However, the contribution of organic carbon content from coal dust of varying coalification degrees is inconsistent. Its active involvement in soil carbon transformation processes and its influence on soil bacterial communities remain to be elucidated. Methods This study conducted a 120-day indoor constant-temperature soil incubation experiment, with sampling carried out at 5, 15, 30, 50, 80, and 120 days of incubation. The research aimed to investigate the impact mechanisms of three coalification degrees of coal dust, lignite, bituminous coal, and anthracite, along with a corresponding control group, on soil carbon dioxide (CO 2 -C) accumulation mineralization, soil active organic carbon, and soil bacterial community structure. Results Lignite exhibited the highest promotion of soil CO 2 -C mineralization, showing a 9.74% increase compared to the control (CK). The impact of the three types of coal dust on soil readily oxidizable organic carbon (ROC) and microbial biomass carbon (MBC) content decreased to varying degrees with increasing incubation time. Furthermore, coal dust was found to enhance the prevalence of dominant bacterial taxa in the soil, with an increase in groups such as Proteobacteria, Actinobacteria, and Acidobacteria, and the extent of the increase was correlated with the coalification degree. Conclusion Coal dust with lower coalification degrees has a stronger impact on the soil compared to higher coalification degrees, and these effects tend to manifest in the short term. Therefore, further exploration of this aspect should focus on long-term effects.