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Title: Microbial Influence on Iodine Speciation at the 200 West Hanford Site - 16549

Abstract

A waste product from nuclear fission, the radioisotope iodine-129 ({sup 129}I) is of environmental concern due to its long half-life (∼16 million years), mobility, and hazardous potential to humans through bioaccumulation in the thyroid gland. The Hanford Site in Richland, Washington, contains two separate {sup 129}I contaminant plumes over 1,500 acres with concentrations of ∼3.5 pCi/L in groundwater samples, exceeding the federal drinking water standard of <1 pCi/L. Consequently, understanding the mechanisms and contributors to iodine speciation is important in order to develop appropriate remediation strategies for iodine in non-aqueous environments such as the vadose zone, the subsurface environment located directly above groundwater. A lack of current remedial techniques is due to the complexity of microbial influence and presence of dissolved organics that impact the transport and speciation of {sup 129}I. Although, iodide (I{sup -}) is thermodynamically favored in the geological support material, based on current pH and Eh ranges at the Hanford Site, groundwater sampling of monitoring wells within the 200 West Area have found the dominant species to be iodate (IO{sub 3}{sup -}) (70.6%) while organo-iodine (25.8%) and iodide (3.6%) were found in far lower quantities. Enrichments of Lower Ringgold sediment from the 200 West Hanford site allowedmore » the isolation of microbial species metabolically involved in the speciation of iodine. Through a series of batch studies and spectrophotometric assays, isolates were found to couple nitrate (NO{sub 3}) reduction with iodate (IO{sub 3}), where iodate reduction was not observed in the absence of nitrate. Additionally, isolates able to oxidize iodide were also identified. Currently, analytical techniques are being developed to further understand the kinetics and enzymatic activity for both of these redox reactions. Ongoing research involves these isolates and their influence on iodine speciation in the presence of organics such as humic acid or lignocellulose. (authors)« less

Authors:
 [1]; ;  [2]
  1. University of Michigan, Ann Arbor, MI (United States)
  2. Pacific Northwest National Laboratory, Richland, WA (United States)
Publication Date:
Research Org.:
WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
OSTI Identifier:
22838319
Report Number(s):
INIS-US-19-WM-16549
TRN: US19V1512083674
Resource Type:
Conference
Resource Relation:
Conference: WM2016: 42. Annual Waste Management Symposium, Phoenix, AZ (United States), 6-10 Mar 2016; Other Information: Country of input: France; 23 refs.; available online at: http://archive.wmsym.org/2016/index.html
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BIOLOGICAL ACCUMULATION; ENVIRONMENT; GROUND WATER; HANFORD RESERVATION; IODATES; IODIDES; IODINE 129; MICROORGANISMS; NITRATES; PLUMES; RADIATION MONITORING; RADIOACTIVE WASTES; REDOX REACTIONS; REMEDIAL ACTION; SEDIMENTS; UNDERGROUND

Citation Formats

Moser, Erin, Lee, Brady, and Lee, Hope. Microbial Influence on Iodine Speciation at the 200 West Hanford Site - 16549. United States: N. p., 2016. Web.
Moser, Erin, Lee, Brady, & Lee, Hope. Microbial Influence on Iodine Speciation at the 200 West Hanford Site - 16549. United States.
Moser, Erin, Lee, Brady, and Lee, Hope. Fri . "Microbial Influence on Iodine Speciation at the 200 West Hanford Site - 16549". United States.
@article{osti_22838319,
title = {Microbial Influence on Iodine Speciation at the 200 West Hanford Site - 16549},
author = {Moser, Erin and Lee, Brady and Lee, Hope},
abstractNote = {A waste product from nuclear fission, the radioisotope iodine-129 ({sup 129}I) is of environmental concern due to its long half-life (∼16 million years), mobility, and hazardous potential to humans through bioaccumulation in the thyroid gland. The Hanford Site in Richland, Washington, contains two separate {sup 129}I contaminant plumes over 1,500 acres with concentrations of ∼3.5 pCi/L in groundwater samples, exceeding the federal drinking water standard of <1 pCi/L. Consequently, understanding the mechanisms and contributors to iodine speciation is important in order to develop appropriate remediation strategies for iodine in non-aqueous environments such as the vadose zone, the subsurface environment located directly above groundwater. A lack of current remedial techniques is due to the complexity of microbial influence and presence of dissolved organics that impact the transport and speciation of {sup 129}I. Although, iodide (I{sup -}) is thermodynamically favored in the geological support material, based on current pH and Eh ranges at the Hanford Site, groundwater sampling of monitoring wells within the 200 West Area have found the dominant species to be iodate (IO{sub 3}{sup -}) (70.6%) while organo-iodine (25.8%) and iodide (3.6%) were found in far lower quantities. Enrichments of Lower Ringgold sediment from the 200 West Hanford site allowed the isolation of microbial species metabolically involved in the speciation of iodine. Through a series of batch studies and spectrophotometric assays, isolates were found to couple nitrate (NO{sub 3}) reduction with iodate (IO{sub 3}), where iodate reduction was not observed in the absence of nitrate. Additionally, isolates able to oxidize iodide were also identified. Currently, analytical techniques are being developed to further understand the kinetics and enzymatic activity for both of these redox reactions. Ongoing research involves these isolates and their influence on iodine speciation in the presence of organics such as humic acid or lignocellulose. (authors)},
doi = {},
url = {https://www.osti.gov/biblio/22838319}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2016},
month = {7}
}

Conference:
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