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Impact of natural organic matter on U speciation and mobility in groundwater

EMSL Project ID
48747
Award DOI
https://dx.doi.org/10.46936/genr.proj.2015.48747/60005671

Abstract

 Uranium (U) contamination of aquifers is a persistent problem at DOE legacy ore processing sites and, contrary to initial predictions, many plumes are not attenuating with natural groundwater flushing. In these sediments, U is typically enriched in organic-rich fine-grained lenses of sediment that are interspersed with the coarser aquifer material. Natural organic matter (NOM) plays an important role in retention and redox transformations of U in these sediments.
The scientific focus of the proposed work is to identify key characteristics of NOM that are likely to be important to U biogeochemistry within the U-enriched zones to constrain the mechanisms controlling U mobility in aquifers. We propose (i) to examine how NOM chemistry influences U speciation through complexation in laboratory batch reactor systems and aquifer sediments, using nano-scale secondary ion mass spectrometry (NanoSIMS) coupled with sub-micron synchrotron-based x-ray microscopy measurements. We further propose (ii) to determine functional group abundances, molecular size and composition in NOM from reactor systems and U-rich zones within aquifer sediments using high-resolution Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) in combination with a suite of solid- and liquid-state nuclear magnetic resonance (NMR) techniques.

Project Details

Project type
Exploratory Research
Start Date
2015-03-11
End Date
2015-09-30
Status
Closed
Released Data Link
https://search.emsl.pnnl.gov/?project_id_search=48747

Team

Principal Investigator

John Bargar
Institution
Environmental Molecular Sciences Laboratory

Co-Investigator(s)

Scott Fendorf
Institution
Stanford University

Team Members

Kristin Boye
Institution
Stanford Linear Accelerator Center

Sharon Bone
Institution
Stanford Linear Accelerator Center

Morris Jones
Institution
Stanford University

Marco Keiluweit
Institution
University of Massachusetts Amherst

Related Publications

Understanding controls on redox processes in floodplain sediments of the Upper Colorado River Basin

Noel V, KE Boye, RK Kukkadapu, SE Bone, JS Lezama Pacheco, E Cardarelli, N Janot, S Fendorf, KH Williams, and J Bargar. 2017. "Understanding the controls on redox processes in floodplain sediments of the Upper Colorado River Basin." Science of the Total Environment 603-604:663-675. doi:10.1016/j.scitotenv.2017.01.109
https://dx.doi.org/10.1016/j.scitotenv.2017.01.109