title: Uranium fate in wetland mesocosms: Effects of plants at two iron loadings with different pH values.
abstract: Small-scale continuous flow wetland mesocosms (∼0.8 L) were used to evaluate how plant roots under different iron loadings affect uranium (U) mobility. When significant concentrations of ferrous iron (Fe) were present at circumneutral pH values, U concentrations in root exposed sediments were an order of magnitude greater than concentrations in root excluded sediments. Micro X-ray absorption near-edge structure (μ-XANES) spectroscopy indicated that U was associated with the plant roots primarily as U(VI) or U(V), with limited evidence of U(IV). Micro X-ray fluorescence (μ-XRF) of plant roots suggested that for high iron loading at circumneutral pH, U was co-located with Fe, perhaps co-precipitated with root Fe plaques, while for low iron loading at a pH of ∼4 the correlation between U and Fe was not significant, consistent with previous observations of U associated with organic matter. Quantitative PCR analyses indicated that the root exposed sediments also contained elevated numbers of Geobacter spp., which are likely associated with enhanced iron cycling, but may also reduce mobile U(VI) to less mobile U(IV) species.
authors: Princeton University, Princeton, NJ 08540, USA.
authors: Paul G
authors: PG
authors: Koster van Groos
authors: Savannah River National Laboratory, Aiken, SC 29808, USA.
authors: Daniel I
authors: DI
authors: Kaplan
authors: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA.
authors: Hyun-Shik
authors: HS
authors: Chang
authors: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA.
authors: John C
authors: JC
authors: Seaman
authors: Savannah River National Laboratory, Aiken, SC 29808, USA.
authors: Dien
authors: D
authors: Li
authors: Pace Analytical Energy Services, Pittsburgh, PA 15238, USA.
authors: Aaron D
authors: AD
authors: Peacock
authors: US EPA, Cincinnati, OH 45268, USA.
authors: Kirk G
authors: KG
authors: Scheckel
authors: Princeton University, Princeton, NJ 08540, USA. Electronic address: jaffe@princeton.edu.
authors: Peter R
authors: PR
authors: Jaffé
mesh_terms: D045302:Geobacter / Q000378:metabolism*; D007501:Iron / Q000032:analysis / Q000737:chemistry*; D010084:Oxidation-Reduction; D018517:Plant Roots / Q000378:metabolism*; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*; D053833:Wetlands; D056928:X-Ray Absorption Spectroscopy
chemical_list: D014875:Water Pollutants, Radioactive; D014501:Uranium; D007501:Iron
keywords: Iron; Plants; Rhizosphere; Uranium fate; Uranium sequestration; Wetlands