Method for determining coal carbon in the reclaimed minesoils contaminated with coal

Minesoils are anthropic soils developed on land disturbed by mining activities. Minesoils developed on the reclaimed surface-mined sites for coal are contaminated with coal particles resulting from mining and reclamation activities. Therefore, the total organic carbon (TOC) pool in these sites is a mixture of coal and plant-derived recent soil organic carbon (SOC). Accurate estimates of SOC pools and C sequestration rates in the reclaimed minesoils (RMS) is limited by the lack of a standard and cost-effective method for determination of coal C concentrations in the RMS. The chemi-thermal method, based on the oxidative resistance of coal, was developed and validated with radiocarbon analysis using selected artificial soil-coal mixtures and minesoil samples. Radiocarbon analysis of RMS samples indicated that minesoils from the top 10-cm depth developing from topsoil applied during reclamation was coal C free. The contribution of coal C and the radiocarbon age of TOC increased with increasing soil depth. The coal C fraction accounted for 0 to 92% of TOC in the RMS samples. The coal C fraction was highly correlated with delta C-13 (r(2) = 0.84), suggesting that stable isotope composition could estimate the coal C concentration in RMS samples. Analysis of coal and artificial soil and coal mixtures indicated that chemi-thermal treatment was effective in removing recent SOC with minimum effect on coal. Analysis of RMS samples indicated that both radiocarbon activity and the chemi-thermal method were effective in estimating coal C concentration in RMS of southeast Ohio. The coal C concentrations for both methods were highly correlated (r(2) = 0.95), suggesting that the chemi-thermal method was as effective as radiocarbon activity measurement in estimating coal C concentration in these soils.