Composition Characteristics of Dissolved Organic Matter at the Vegetation-Soil Interface Under the Influence of Mining Disturbances

The contradiction between coal mining and environmental protection is becoming increasingly acute. In this study, we analyzed the distribution of carbon content and the components and structural characteristics of dissolved organic matter (DOM) at the vegetation-soil interface of mine dumps and explored the potential environmental mechanism of the recovery process. The study results indicated that the DOM content at the vegetation-soil interface was 320.82-403.81 mg/kg, decreasing in the first 1-3 years and then increasing between years 5 and 7. With increasing time from the creation of the dump, hydrophilic and microbial materials at the vegetation-soil interface turned, most of which were integrated into humic-like substances and protein-like substances. Moreover, the adsorption capacity of DOM to organic pollutants and metal ions decreased, increasing the potential risk of vegetation-soil interface pollution. However, the content of newly formed humic acid in DOM gradually enhanced, improving the fertility of the vegetation-soil interface. Vegetation types and pH were the key factors affecting the spatial distribution of carbon content and the composition characteristics of DOM at the vegetation-soil interface. Thus, studying the composition characteristics of DOM in the vegetation-soil interface can help establish a relationship with the soil quality and offer novel ideas for the management of the mining dumps.