123rd General Meeting of the KCS

Type Oral Presentation
Area Student Oral Presentation
Room No. Room 203
Time THU 09:45-10:00
Code ENVR.O-4
Subject Mineral precipitates and microbial community compositions in groundwater from inside waste disposal site
Authors Bak Noon Ham, Man Jae Kwon1,*
Energy Environment Policy & Technology, KU-KIST Green School, Korea University,, Korea
1Earth and Environmental Sciences, Korea University, Korea
Abstract Constructing deep underground waste storage sites can cause dramatic changes in groundwater quality as well as groundwater flow, and these changes subsequently influence subsurface microbial activities and community compositions. To understand how the underground construction influences the subsurface environments, we investigated geochemical variations, major mineral precipitates and microbial community compositions at different locations of the waste disposal sites (WS1~6) in the vicinity of coastal region in South Korea. Groundwater drained from WS1, WS2, WS3, and WS5 was Ca-Cl-type with relatively high Total Dissolved Solids (TDS), while that from WS4 and WS6 was Ca-Na-HCO3 type. Br/Cl and δD/δ18O ratios showed that the groundwaters of WS1(15%), 3(2%) and 5(5%) were affected by seawater. Various sulfate reducing bacteria were identified with relatively high sulfate due to the saltwater mixing at these locations. High abundance of Geobacter and Gallionella at WS3 indicated that they contributed to a high Fe concentration in groundwater and the formation of various iron minerals (i.e., Fe(OH)3, α-FeOOH, FeCO3, green rust). WS5 and WS6 showed extremely high pH (>10) and very high abundance of Hydrogenophaga previously discovered in alkaline groundwater (pH>10) or sediment as alkali-tolerant bacteria. Thermoanaerobacterales, halophilic and alkalithermophilic bacteria, was also predominant at WS5 and WS6. The results showed that groundwater drained from inside the waste disposal site was distinct at each location and strongly influenced by localized geochemical conditions (i.e., high alkalinity, salinity and oxidation). These groundwaters further impact mineral precipitates and microbial community structure.
E-mail snow6605@naver.com