Characterizing organic carbon dynamics during biostimulation of a uranium contaminated field site
| Autor: | Kenneth H. Williams, Martin A. Dangelmayr, Linda Figueroa, Philip E. Long |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
010504 meteorology & atmospheric sciences
Environmental remediation Environmental Science and Management chemistry.chemical_element Excitation-emission matrices 01 natural sciences Biostimulation Soluble microbial products Dissolved organic carbon Environmental Chemistry Organic matter Groundwater 0105 earth and related environmental sciences Earth-Surface Processes Water Science and Technology chemistry.chemical_classification Total organic carbon Carbon sink Agronomy & Agriculture 04 agricultural and veterinary sciences Uranium Geochemistry chemistry Environmental chemistry 040103 agronomy & agriculture 0401 agriculture forestry and fisheries Other Chemical Sciences Carbon Bioremediation |
| Zdroj: | Biogeochemistry, vol 143, iss 1 |
| Popis: | Uranium contamination of groundwater remains a pressing problem at many former uranium mining and milling operations, such as the Rifle, Integrated Field Research Challenge (IFRC) site. Biostimulation of the subsurface with an organic carbon source such as acetate, followed by the microbially-induced reductive precipitation of uranium has been proposed as an effective remediation strategy. While uranium bioreduction has been studied in several field experiments, the transformation and fate of injected carbon remains poorly understood. This study evaluated the impact of added organic carbon on the long-term biogeochemical attenuation of uranium in the subsurface of a former mill tailings site. Fluorescence and ultraviolet–visible absorbance analyses were used together with dissolved organic carbon (DOC) measurements to track organic carbon dynamics during and post-biostimulation of the 2011 Rifle IFRC experiment. An electron mass balance was performed on well CD01 to account for any unidentified carbon sinks. Measured DOC values increased to 1.76mM-C during biostimulation, and to 3.18mM-C post-biostimulation over background DOC values of 0.3–0.4mM-C. Elevated DOC levels persisted for 90days after acetate injections ceased. The electron mass balance revealed that assumed electron acceptors would not account for the total amount of acetate consumed. Excitation–emission matrices showed an increase in signals associated with soluble microbial products, during biostimulation, which disappeared post-biostimulation despite an increase in total DOC. Specific ultraviolet absorbance analyses, indicated that DOC present post-biostimulation is less aromatic in nature, compared to background DOC. Our results suggest that microbes convert injected acetate into a form of solid phase organic matter that may be available to sustain iron reduction post-stimulation. |
| Databáze: | OpenAIRE |
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