https://scholar.korea.ac.kr/handle/2021.sw.korea/341 Sun, 05 Apr 2026 15:53:17 GMT 2026-04-05T15:53:17Z https://scholar.korea.ac.kr/handle/2021.sw.korea/271385 Title: Comprehensive multimetal isotopic model for regional-scale water management in a mining city: Tracing contamination sources, pathways, and geochemical processes using Cu, Mo, S-O, and Zn isotopes Authors: Kim, Duk-Min; Batsaikhan, Bayartungalag; Yun, Seong-Taek; Im, Dae-Gyu; Seo, Hyeon-Soo Abstract: Major mining cities worldwide have been suffering from diverse contamination sources such as tailings, mine drainages, geology enriched with toxic metals, and other industrial and domestic sources. This study established a multi-isotopic comprehensive model for elucidating water contamination sources and geochemical reactions in the city of Erdenet in Mongolia. The Erdenet city was contaminated with As, Cu, Mo, Zn, and SO42-, and we used isotopes of Cu, Mo, Zn, and S-O in SO42-. Contamination sources for groundwater and surface water were differentiated as tailings dump, excavated ore, heap leaching, ash pond of a power plant, and argillic alteration zone. Groundwater in the residential area was influenced by the argillic alteration zone, as indicated by low S34SSO4 and high S65Cu values, while S66Zn fingerprints may have been masked by adsorption and mixing. Additionally, S98Mo fingerprints from two major Mo contamination sources (the ash pond and tailings dump) were evident in the stream. The tailings dump substantially impacted S65Cu, S98Mo, and S66Zn values in the stream, with isotopic fractionation occurring through oxidative dissolution and adsorption. Furthermore, to assess oxidative dissolution of sulfides and adsorption, delta 65Cu and delta 98Mo+ delta 66Zn were found to be particularly useful, respectively. This study highlights the effectiveness of multimetal isotopic ratios in tracing contamination sources and geochemical processes in regions with diverse contaminants, presenting a robust spatial model for isotopic fingerprinting. Fri, 15 Aug 2025 00:00:00 GMT https://scholar.korea.ac.kr/handle/2021.sw.korea/271385 2025-08-15T00:00:00Z https://scholar.korea.ac.kr/handle/2021.sw.korea/268120 Title: Biofilm development on fractured rock in oligotrophic nitrate-rich groundwater: An in-situ bioreactor study Authors: Park, Kanghyun; Kim, Kue-Young; Kirk, Matthew F.; Kwon, Man Jae Abstract: Biofilms drive all biogeochemical processes and represent the main mode of existence for active microbial life. Many past studies examined biofilm formation under static and eutrophic conditions, but those conditions are not representative of typical groundwater environments. In this study, we developed in situ bioreactors and methodologies to examine the influence of subsurface properties such as redox condition and lithology on the properties of naturally formed biofilms in two adjacent wells, a 30-m deep well completed in alluvium and a 120m deep well in gneiss bedrock. The bulk chemistry of groundwater from the wells was similar, with neutral pH and abundant nitrate (21.9-24.6 mg/L), but redox conditions differed with depth (alluvial: oxic, gneiss bedrock: anoxic). Microbial community analysis revealed distinct clustering of biofilm community composition with the groundwater environment. Biofilm communities were consistently assembled by deterministic processes whereas planktonic communities had a higher influence of stochastic processes. Alluvial biofilms exhibited more diverse communities mainly composed of organotrophic aerobes capable of nitrate utilization. Bedrock biofilms indicated similar community compositions with groundwater where anaerobic denitrifiers coupled with sulfur oxidizers were dominant. Visualization and biomass quantification revealed distinct morphologies and development of biofilm along rock types and groundwater environments. Biofilm on gneiss surface had more biomass and formed a thin layered structure, compared to sandstone biofilm which had a randomly distributed pattern, implying that the morphology of biofilm was governed by the properties of the rock. Attached to unattached (planktonic) microbe ratios ranged from 3.9 x 103 to 1.2 x 104: 1 in the gneiss surface and 3.4 x 102 to 4.2 x 102: 1 in the sandstone surface in bedrock groundwater environment. Taken together, this study advances our understanding of subsurface biomass abundance and demonstrates that the in-situ bioreactors are effective for cultivating and analyzing of subsurface biofilms. Based on the specific field conditions tested, we found that biofilm can form stably on fractured rock surfaces within a year, with groundwater redox conditions shaping community composition and rock types determining biofilm volume and morphology. The methodologies presented here can be extended to other subsurface environments with varying groundwater geochemistry and lithology, which will help further refine estimates of microbial life and its role in subsurface ecosystems. Sun, 01 Jun 2025 00:00:00 GMT https://scholar.korea.ac.kr/handle/2021.sw.korea/268120 2025-06-01T00:00:00Z https://scholar.korea.ac.kr/handle/2021.sw.korea/269252 Title: Cesium retention in powdered granite under saline and alkaline conditions: Role of biotite in deep geological repositories Authors: Goo, Ja-Young; Kim, Jin-Seok; Lee, Sang-Ho; Kwon, Jang-Soon; Jo, Ho Young Abstract: Natural granite barriers in deep geological repositories can serve as a final barrier against the migration of hazardous radionuclides such as 137Cs into the ecosystem. In this study, the Cs retention characteristics of natural granite barrier under evolved repository conditions (i.e., alkaline and saline conditions) were investigated with a particular focus on the role of biotite. The partial dissolution of aluminosilicate minerals and some exfoliation at the edges of biotite were observed in alkaline solutions, whereas no changes were observed in saline solutions. These alterations slightly affected the Cs retention capabilities of granite samples under alkaline conditions during the specified test period. Cs retention in granite mainly occurred via cation exchange with K ions within the interlayers of biotite. During the ion exchange process, Cs ions competed with major cations in both alkaline and saline solutions, such as Mg, K, and Na, varying Cs retention capacity. Moreover, this variation was particularly pronounced in saline solutions. These findings indicate a possible mechanism for the retention of radioactive cations in natural granite barriers under long-term evolved repository conditions. Accordingly, natural granite barriers enriched with biotite can effectively retain radioactive cations and inhibit their migration into the ecosystem. Sun, 01 Jun 2025 00:00:00 GMT https://scholar.korea.ac.kr/handle/2021.sw.korea/269252 2025-06-01T00:00:00Z https://scholar.korea.ac.kr/handle/2021.sw.korea/277510 Title: Natural Hydrogen Systems Chapter 17_Potential occurrence and reservoirs of natural hydrogen based on the geological and tectonic setting of the Korean Peninsula Authors: Kim Hyeong Soo Sun, 01 Jun 2025 00:00:00 GMT https://scholar.korea.ac.kr/handle/2021.sw.korea/277510 2025-06-01T00:00:00Z