Interactions among phosphate amendments, microbes and uranium mobility in contaminated sediments

Anna Sophia Knox, R. L. Brigmon, D. I. Kaplan, M. H. Paller

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The use of sequestering agents for the transformation of radionuclides in low concentrations in contaminated soils/sediments offers considerable potential for environmental cleanup. This study evaluated the influence of three types of phosphate (rock phosphate, biological phosphate, and calcium phytate) and two microbial amendments (Alcaligenes piechaudii and Pseudomonas putida) on U mobility. All tested phosphate amendments reduced aqueous U concentrations more than 90%, likely due to formation of insoluble phosphate precipitates. The addition of A. piechaudii and P. putida alone were found to reduce U concentrations 63% and 31%, respectively. Uranium removal in phosphate treatments was significantly reduced in the presence of the two microbes. Two sediments were evaluated in experiments on the effects of phosphate amendments on U mobility, one from a stream on the Department of Energy's Savannah River Site near Aiken, SC and the other from the Hanford Site, a Department of Energy facility in Washington state. Increased microbial activity in the treated sediment led to a reduction in phosphate effectiveness. The average U concentration in 1 M MgCl2 extract from U contaminated sediment was 437 μg/kg, but in the same sediment without microbes (autoclaved), the extractable U concentration was only 103 μg/kg. The U concentration in the 1 M MgCl2 extract was ∼ 0 μg/kg in autoclaved amended sediment treated with autoclaved biological apatite. These results suggest that microbes may reduce phosphate amendment remedial effectiveness.

Original languageEnglish (US)
Pages (from-to)63-71
Number of pages9
JournalScience of the Total Environment
Issue number2-3
StatePublished - Jun 1 2008
Externally publishedYes


  • Alcaligenes piechaudii
  • Apatite
  • Microbial activity
  • Pseudomonas putida
  • Uranium

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


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