Surface Coal Mineland Reclamation Using a Dry Flue Gas Desulfurization Product and Soil: Long-Term Microbial Responses.

Abandoned surface coal mined lands are an environmental concern worldwide because of their potential strong negative impact on water and soil quality. A field study was conducted to investigate the use of a dry flue gas desulfurization (FGD) product and soil 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 the soil treatment included 20 cm of resoil material plus 157 Mg ha^-1 of agricultural limestone. A grass-legume sward was planted, and microbial abundance and diversity in the soil were analyzed in the 20^th year after treatments using pyrosequencing of bacterial 16S rRNA and eukaryotic 18S rRNA genes. The results revealed approximately 8,000 and 2000 operational taxonomic units (OTU) for bacteria and eukaryotes, respectively, in the treated soil, and 3,000 and 1000 in the untreated soil. The five most abundant bacterial phyla were Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, and Chloroflexi. There were more Acidobacteria in the untreated than treated soil. Fungi represented approximately 70% of the total eurkayotes in treated soils and more than 90% in the untreated soil. Microbial diversity in the reclaimed coal mine plots was significantly increased compared to untreated areas 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 create a more diverse microbial community that is also less dominated by Acidobacteria.