Research highlights


Hexavalent uranium storage mechanisms in wet-dry cycled sediments at contaminated DOE sites in the Western U.S

Noël, V.; Boye, K.; Kukkadapu, R. K.; Li, Q.; Bargar, J. R. Uranium storage mechanisms in wet-dry redox cycled sediments. Water Research. Water Research 152 (2019), 251-263;

New process observed for uranium accumulation and release at contaminated DOE sites. Read more >



A Simplified Way to Predict the Function of Microbial Communities

K. Boye, A.H. Hermann, M.V. Schaefer, M.M. Tfaily, and S. Fendorf, “Discerning microbially mediated processes during redox transitions in flooded soils using carbon and energy balances.” Frontiers in Environmental Science (2018) [DOI: 10.3389/fenvs.2018.00015]

This pioneering study offers an easier approach to study how microbes work and could help scientists advance models of the cycling of elements and nutrients in frequently flooded soils. Read more >


Sorption to Organic Matter Controls Uranium Mobility

Bone SE, Dynes JJ, Cliff J, & Bargar JR “Uranium(IV) adsorption by natural organic matter in sediments.” Proceedings of the National Academy of Sciences of the United States of America 114(4), 711-716. [10.1073/pnas.1611918114]

A new multi-technique study using X-ray absorption spectroscopy at SSRL, nanoscale secondary Ion mass spectroscopy at EMSL, and scanning transmission X-ray microscopy at the CLS has revealed crisp new details about the mechanisms of uranium binding in sediments.  Surfaces of natural organic matter bind uranium more strongly than minerals under field-relevant conditions. Read more >

Thermodynamic preservation of carbon in anoxic environments

Boye, K., Noël, V., Tfaily, M.M., Bone, S.E., Williams, K.H., Bargar, J.R., Fendorf, S. (2017) Thermodynamically controlled preservation of organic carbon in floodplains. Nature Geoscience [10.1038/ngeo2940]

A new study combining X-ray absorption spectroscopy (XAS) at SSRL with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) at EMSL provides new insights on why carbon persists in waterlogged soil and subsurface sediments . Energetic constraints prevent microbial respiration of certain organic carbon compounds, leaving a pool of water-soluble carbon that is susceptible to oxidation or export and subsequent decomposition in downstream, aerated environments. Read more >

Combined Fe and S speciation tracks redox conditions in shallow alluvial sediments

Noël V, Boye K, Kukkadapu RK, Bone SE, Lezama Pacheco JS, Cardarelli E, Janot N, Fendorf S, Williams KH, Bargar JR (2017) Understanding controls on redox processes in floodplain sediments of the Upper Colorado River Basin. Science of The Total Environment,

Detailed characterization of the molecular structures of Fe and S, on depth-resolved field samples from floodplain sediments, were performed using x-ray absorption spectroscopy (XAS) and X-ray microspectroscopy at SSRL combined with mössbauer spectroscopy at EMSL. The results revealed that organic carbon content, moisture, and particle size control the distribution and reactivity of redox constraints in the floodplain subsurface. Read more >