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Title: Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

Abstract

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradient wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation ofmore » Se oxyanions at ISR sites.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6]; ORCiD logo [7]; ORCiD logo [7];  [7];  [3]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Earth and Planetary Science
  2. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy and Management
  3. Univ. of California, Berkeley, CA (United States). Dept. of Earth and Planetary Science; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Geology
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  6. Uranium Resources, Inc., Centennial, CO (United States)
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1345152
Report Number(s):
LA-UR-16-24690
Journal ID: ISSN 0013-936X
Grant/Contract Number:
AC52-06NA25396; AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 50; Journal Issue: 20; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Planetary Sciences

Citation Formats

Anirban, Basu, Schilling, Kathrin, Brown, Shaun T., Johnson, Thomas M., Christensen, John N., Hartmann, Matt, Reimus, Paul William, Heikoop, Jeffrey Martin, Woldegabriel, Giday, and DePaolo, Donald J.. Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine. United States: N. p., 2016. Web. doi:10.1021/acs.est.6b01464.
Anirban, Basu, Schilling, Kathrin, Brown, Shaun T., Johnson, Thomas M., Christensen, John N., Hartmann, Matt, Reimus, Paul William, Heikoop, Jeffrey Martin, Woldegabriel, Giday, & DePaolo, Donald J.. Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine. United States. doi:10.1021/acs.est.6b01464.
Anirban, Basu, Schilling, Kathrin, Brown, Shaun T., Johnson, Thomas M., Christensen, John N., Hartmann, Matt, Reimus, Paul William, Heikoop, Jeffrey Martin, Woldegabriel, Giday, and DePaolo, Donald J.. 2016. "Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine". United States. doi:10.1021/acs.est.6b01464. https://www.osti.gov/servlets/purl/1345152.
@article{osti_1345152,
title = {Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine},
author = {Anirban, Basu and Schilling, Kathrin and Brown, Shaun T. and Johnson, Thomas M. and Christensen, John N. and Hartmann, Matt and Reimus, Paul William and Heikoop, Jeffrey Martin and Woldegabriel, Giday and DePaolo, Donald J.},
abstractNote = {One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradient wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.},
doi = {10.1021/acs.est.6b01464},
journal = {Environmental Science and Technology},
number = 20,
volume = 50,
place = {United States},
year = 2016,
month = 8
}

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