Purpose <p>Whereas the soil organic carbon (SOC) stock dynamics of drained peatlands have been extensively studied, the role of soil inorganic carbon (SIC) and redistribution of SOC and SIC due to the anthropogenic activities remain understudied. This study aims to assess carbon stock composition across typical land-use patterns of the drained part of the eutrophic Tarmanskoe Peatland (West Siberia, Russia).</p> Methods <p>Carbon stocks were estimated down to 1&#xa0;m depth of soil profile. The SOC turnover rate assessed based on changes of stable carbon isotope signatures (δ¹³C) and SOC content with depth. Soil microstructure was analyzed by optical microscopy.</p> Results <p>SOC stock losses due to peat extraction ranged from 488 to 943 t ha⁻¹, exceeding those observed under agricultural use by several fold. In contrast, the naturally rewetted site exhibited more than a twofold increase in SOC stocks compared to adjacent dry meadow. Also, the SOC turnover rate is the fastest in the rewetted meadow and the lowest in the dry meadow with highest SIC content. A negative correlation was found between SOC turnover rate and SIC content. Drained sites subjected to anthropogenic impacts demonstrated increased SIC stocks, with macro- and micromorphological evidences of pedogenic carbonates forming in the upper soil horizons.</p> Conclusions <p>Anthropogenic transformations of eutrophic peatlands have resulted in significant variations in the residual peat thickness and carbon stock composition, notably increasing SIC stocks. However, carbonates could potentially contribute to stabilization of residual soil organic matter. Thus, distinguishing between SOC and SIC stocks is essential when evaluating sequestration potential and designing rewetting projects.</p>