Uranium Redistribution Due to Water Table Fluctuations in Sandy Wetland Mesocosms
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- 作者：Emily R. Gilson ; Shan Huang ; Paul G. Koster van Groos ; Kirk G. Scheckel ; Odeta Qafoku ; Aaron D. Peacock ; Daniel I. Kaplan ; Peter R. Jaff茅
- 刊名：Environmental Science & Technology
- 出版年：2015
- 出版时间：October 20, 2015
- 年：2015
- 卷：49
- 期：20
- 页码：12214-12222
- 全文大小：378K
- ISSN：1520-5851
文摘
To understand better the fate and stability of immobilized uranium (U) in wetland sediments, and how intermittent dry periods affect U stability, we dosed saturated sandy wetland mesocosms planted with Scirpus acutus with low levels of uranyl acetate for 4 months before imposing a short drying and rewetting period. Concentrations of U in mesocosm effluent increased after drying and rewetting, but the cumulative amount of U released following the dry period constituted less than 1% of the total U immobilized in the soil during the 4 months prior. This low level of remobilization suggests, and XANES analyses confirm, that microbial reduction was not the primary means of U immobilization, as the U immobilized in mesocosms was primarily U(VI) rather than U(IV). Drying followed by rewetting caused a redistribution of U downward in the soil profile and to root surfaces. Although the U on roots before drying was primarily associated with minerals, the U that relocated to the roots during drying and rewetting was bound diffusely. Results show that short periods of drought conditions in a sandy wetland, which expose reduced sediments to air, may impact U distribution without causing large releases of soil-bound U to surface waters.