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Park SY, Zhang Y, O'Loughlin EJ, Jo HY, Kwon JS, Kwon MJ. Temperature-dependent microbial reactions by indigenous microbes in bentonite under Fe(III)- and sulfate-reducing conditions. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133318. [PMID: 38154187 DOI: 10.1016/j.jhazmat.2023.133318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 12/09/2023] [Accepted: 12/17/2023] [Indexed: 12/30/2023]
Abstract
Bentonite is a promising buffer material for constructing spent nuclear fuel (SNF) repositories. However, indigenous microbes in bentonite can be introduced to the repository and subsequent sealing of the repository develops anoxic conditions over time which may stimulate fermentation and anaerobic respiration, possibly affecting bentonite structure and SNF repository stability. Moreover, the microbial activity in the bentonite can be impacted by the heat generated from radionuclides decay. Therefore, to investigate the temperature effect on microbial activities in bentonite, we created microcosms with WRK bentonil (a commercial bentonite) using lactate as the electron donor, and sulfate and/or ferrihydrite (Fe(III)) as electron acceptors with incubation at 18 ℃ and 50 ℃. Indigenous WRK microbes reduced sulfate and Fe(III) at both temperatures but with different rates and extents. Lactate was metabolized to acetate at both temperatures, but only to propionate at 18 ℃ during early-stage microbial fermentation. More Fe(III)-reduction at 18 ℃ but more sulfate-reduction at 50 ℃ was observed. Thermophilic and/or metabolically flexible microbes were involved in both fermentation and Fe(III)/sulfate reduction. Our findings illustrate the necessity of considering the influence of temperature on microbial activities when employing bentonite as an engineered buffer material in construction of SNF repository barriers.
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Affiliation(s)
- Su-Young Park
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea
| | - Yidan Zhang
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea
| | | | - Ho Young Jo
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea
| | - Jang-Soon Kwon
- Korea Atomic Energy Research Institute, Daejeon 34057, South Korea
| | - Man Jae Kwon
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea.
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Xu H, You C, Tan B, Xu L, Liu Y, Wang M, Xu Z, Sardans J, Peñuelas J. Effects of livestock grazing on the relationships between soil microbial community and soil carbon in grassland ecosystems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 881:163416. [PMID: 37059137 DOI: 10.1016/j.scitotenv.2023.163416] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/23/2023] [Accepted: 04/06/2023] [Indexed: 06/01/2023]
Abstract
Livestock grazing of grassland ecosystems may induce shifts in microbe community traits and soil carbon (C) cycling; however, impacts of grassland management (grazing) on soil C- microbe community trait (microbial biomass, diversity, community structure, and enzyme activity) relationships are unclear. To address this, we conducted a global meta-analysis of 95 articles of livestock grazing studies that vary in grazing intensities (light, moderate, and high) and durations (<5 years, 5-10 years, and > 10 years). We found that gazing decreased soil organic carbon content (SOC; 10.1 %), and activities of the enzymes of saccharase (SA; 31.1 %), urease (UA; 7.0 %), and acid phosphatase (11.9 %) in topsoil. Meanwhile, the SOC, soil microbial biomass and enzyme activities consistently decreased as grazing intensity and duration prolonged. Furthermore, we observed strong linear relationships of microbe community traits with SOC (p < 0.05), but weak relationships with soil N or P (p > 0.05) in grasslands, which also depends on the grazing intensity and duration. In conclusion, our results indicate that traits of soil carbon content, soil microbe community, and in particular their relationships in global grasslands are overall significantly affected by livestock grazing, but the effects strongly depend on the grazing intensity and duration.
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Affiliation(s)
- Hongwei Xu
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Chengming You
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Bo Tan
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Lin Xu
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Yang Liu
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Minggang Wang
- The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, China.
| | - Zhenfeng Xu
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China.
| | - Jordi Sardans
- CSIC, Global Ecology Unit CREAF-CSIC-UAB, 08913 Bellaterra, Catalonia, Spain; CREAF, 08913 Cerdanyola del Vallès, Catalonia, Spain; Nonlinear Analysis and Applied Mathematics (NAAM)-Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80257, Jeddah 21589, Saudi Arabia
| | - Josep Peñuelas
- CREAF, 08913 Cerdanyola del Vallès, Catalonia, Spain; Nonlinear Analysis and Applied Mathematics (NAAM)-Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80257, Jeddah 21589, Saudi Arabia
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