Abstract: Soil organic carbon and its active components represent soil fertility and are sensitive to changes of soil quality. This study examined soil organic carbon and its influencing factors under different reclaimed vegetations of coal waster pile. Findings from this study are of great significance to ascertain the quality and fertility of reclaimed soil and to guide the selection of vegetation types for the reclamation of coal waster pile. The concentrations of total soil organic carbon (SOC), dissolved organic carbon (DOC), watersoluble organic carbon (WSOC), microbial biomass carbon (MBC), light fraction organic carbon (LFOC), and heavy fraction organic carbon (HFOC) in 0-10 cm and 10-20 cm soil layers were measured in two land types (grassland and woodland reclaimed for nine years) of Caocun coal waste pile in Huozhou, Shanxi Province. The relationships between soil organic carbon content and soil environmental factors were analyzed. The results showed that: (1) SOC and HFOC contents in grassland were 26.1% and 70.5% higher than that in woodland, and the LFOC contents was 53.1% lower, while the DOC, WSOC and MBC were similar in both vegetation types. This result indicated that the concentrations of SOC in grassland was higher than that in woodland, and such increment was mainly embodied by HFOC content. There was no significant difference in the active components of SOC. (2) Soil TN, TP, AN, C/N, clay content, and pH affected SOC and its active components. Specifically, soil TN, AN, TP, and pH were the key factors influencing SOC and its components under both vegetation types. Therefore, improving soil N, P and reducing soil pH may promote the accumulation of soil organic carbon in reclaimed soil in coal waster pile.

Key words: PM_2.5, simulation, green space, dust detention service, Haidian District.