Aquifer microbial reduction-oxidation reactions at a uranium contaminated site

Pettinger, Catherine

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https://hdl.handle.net/2142/122949 Copy

Description

Title

Aquifer microbial reduction-oxidation reactions at a uranium contaminated site

Author(s)

Pettinger, Catherine

Issue Date

2024-04-24

Keyword(s)

• uranium
• contamination

Abstract

Groundwater contamination at uranium mill sites continues to present a challenge at sites across the United States and the world. Typical remediation strategies take advantage of microbial reduction reactions to immobilize uranium; generally U(VI) is more soluble compared to U(IV). However, this strategy is limited by U(IV) abiotic reoxidation if strong reducing conditions are not maintained. This study aims to decipher microbial contribution to U speciation during and after oxic carbonate-poor injections followed by oxic carbonate-rich injections at a former uranium mill site near Riverton, WY. We performed nine redox tests on groundwater microorganisms collected at the site in August 2023 compared to sterile groundwater controls. Sites tested included within, upgradient, and downgradient of the former source zone. From these it was seen that microorganisms at various locations across the aquifer are capable of Fe, Mn, and SO4 reduction. These microbial reactions could influence U mobility through depletion of Fe- and Mn-oxides that create sorption sites for U. If U is bound to metal oxides, then activity changes of these microorganisms due to injections will change U mobility. Continued experiments are being conducted to decipher how the microbial community responds to injection conditions and how this influences uranium speciation.

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https://youtu.be/cDtzGw9vuQc

Type of Resource

• text
• still image

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