Hydrogeochemical and microbial characteristics in aquifers contaminated with leachate from animal carcass disposal sites

초록

During the Korean foot-and-mouth disease outbreak in 2010-2011, about 3.38 million pigs and cattle were slaughtered and disposed into 4,600 burial pits around the country. In this study, the hydrogeochemical characteristics of landfill leachate and its impact on microbial communities in soils and groundwater were investigated at two hydrogeologically different burial sites; one disposal site (landfill D) is located in a flat area, and the other (landfill Y) is located on a mountain slope. The hydrogeochemical parameters (i.e., EC, HCO3 (-), Cl-, Ca2+, DOC, and NH4 (+)) in the monitoring well of landfill Y showed higher values than those in landfill D. The EC, Cl-, HCO3 (-), Ca2+, DOC, and NH4 (+) values increased until July and decreased in October 2011, because the leachate was regularly pumped and treated during the summer, and water recharged by summer precipitation was infiltrated into the landfill. Relatively anaerobic conditions were observed in monitoring wells (I107-1 and Y-1) at two disposal sites with low DO, NO3 (-), and SO4 (2-) and high Fe2+ and Mn2+ concentration. The dynamic of microbial community structure of aquifers and leachate from animal carcass disposal was analyzed using 16S rRNA gene-based pyrosequencing. Microbial communities affected by the release of landfill leachate at the two burial sites showed clear differences from each other. Bacterial communities in background water (BA-1) and in the aquifer of landfill D were similar, whereas the aquifer (Y-1) and leachate (Y-2) of landfill Y had bacterial communities that had significantly deviated from those of background water. Microbial communities in their groundwater monitoring wells showed distinct patterns due to the amount of leachate caused by hydraulic gradient in each landfill. This finding indicates that hydrogeological conditions are critically important for establishing a landfill site and controlling landfill leachate.

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