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Gankhurel B, Fukushi K, Davaasuren D, Imai E, Kitajima T, Udaanjargal U, Gerelmaa T, Sekine Y, Takahashi Y, Hasebe N. Arsenic and uranium contamination of Orog Lake in the Valley of Gobi Lakes, Mongolia: Field evidence of conservative accumulation of U in an alkaline, closed-basin lake during evaporation. JOURNAL OF HAZARDOUS MATERIALS 2022; 436:129017. [PMID: 35525221 DOI: 10.1016/j.jhazmat.2022.129017] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/16/2022] [Accepted: 04/24/2022] [Indexed: 06/14/2023]
Abstract
The shrinkage of inland, alkaline, and saline lakes has caused the elevation of arsenic and uranium concentrations in lake water. However, the chemical reactions associated with these enrichments remain unclear. We conducted a five-year study of the water chemistry of Orog Lake (Mongolia) and the chemical and spectroscopic characteristics of the sediment to determine the geochemical behavior of arsenic and uranium during evaporation. The arsenic and uranium concentrations increased as evaporation caused the lake to shrink. The maximum concentrations of arsenic and uranium exceeded 200 µg/L and 600 µg/L, respectively, when the lake area was the smallest. Comparisons of the monitoring results with predictions of geochemical modeling suggested that some arsenic was removed from the lake water under highly desiccated conditions. Sequential extraction and X-ray absorption near-edge structure analyses showed that ferrihydrite can take up As(V). The accumulation of uranium could be reproduced by considering only evaporation. The conservative behavior of uranium can be explained by the low affinity of U(VI) for carbonate and ferrihydrite at pH > 9 and high dissolved inorganic carbon concentrations. The ubiquitous formation of extremely soluble U-bearing salts after the complete desiccation of inland lakes may thus become a serious threat to limnetic ecosystems.
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Affiliation(s)
- Baasansuren Gankhurel
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan.
| | - Keisuke Fukushi
- Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan.
| | - Davaadorj Davaasuren
- Department of Geography, School of Art & Sciences, The National University of Mongolia, Ulaanbaatar 210646, Mongolia
| | - Eigo Imai
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Takuma Kitajima
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Uyangaa Udaanjargal
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Tuvshin Gerelmaa
- Department of Geography, School of Art & Sciences, The National University of Mongolia, Ulaanbaatar 210646, Mongolia
| | - Yasuhito Sekine
- Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Yoshio Takahashi
- Department of Earth and Planetary Sciences, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan; Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, 305-0801, Japan
| | - Noriko Hasebe
- Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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