Surface coal mine land reclamation using a dry flue gas desulfurization product: Long-term biological response

Abandoned surface coal mined lands are a worldwide environmental concern due to their low productivity and potential negative impact on water and soil quality. A field study was conducted to investigate the use of a dry flue gas desulfurization (FGD) product, i.e. a fluidized bed combustion (FBC) product, for reclamation of an abandoned surface coal mined land in Ohio, USA. The FGD product was applied to the mine site at a rate of 280 Mg ha−1 alone or with 112 Mg ha−1 yard waste compost, and these treatments were compared to a conventional reclamation treatment that included 20 cm of resoil material plus 45 Mg ha−1 of agricultural limestone. A grass-legume sward was planted, and plant biomass yields and elements in plant tissues were determined as long as 16 years after treatments. Bacterial populations and diversity and microbial biomass C in the reclaimed surface coal mined land were analyzed in the 16th year after treatments. Compared with the conventional soil treatment, plant biomass on plots treated with FGD product was lower in the first and third years, not different in the 14th year, and higher in the 16th year after application. Magnesium, S, Mo and B concentrations in plant tissues were increased by the treatments with FGD product in the first three years but not in the 14th year after application, and the heavy metals measured were not significantly increased. Bacterial populations and diversity and microbial biomass C in the reclaimed coal mine plots were significantly increased compared to adjacent untreated area and were generally similar among reclamation treatments. These results suggest that use of FGD product, used alone or in combination with compost, for reclamation of acidic surface coal mined lands can provide effective, long-term remediation.