Trace contaminant concentration affects mineral transformation and pollutant fate in hydroxide-weathered Hanford sediments

Nicolas Perdrial, Nelson Rivera, Aaron Thompson, Peggy A. O'Day, Jon Chorover

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Prior work has shown that when silicaceous sediments are infused with caustic radioactive waste, contaminant fate is tightly coupled to ensuing mineral weathering reactions. However, the effects of local aqueous geochemical conditions on these reactions are poorly studied. Thus, we varied contaminant concentration and pCO 2 during the weathering of previously uncontaminated Hanford sediments over 6 months and 1 year in a solution of caustic waste (pH 13, high ionic strength). Co-contaminants Sr, Cs and I were added at " low" (Cs/Sr: 10 -5m; I: 10 -7m) and " high" (Cs/Sr: 10 -3m; I: 10 -5m) concentrations, and headspace was held at atmospheric or undetectable (<10ppmv) CO 2 partial pressure. Solid phase characterization revealed the formation of the zeolite chabazite in " high" samples, whereas feldspathoids, sodalite and cancrinite, were formed preferentially in " low" samples. Sr, Cs and I were sequestered in all reacted sediments. Native calcite dissolution in the CO 2-free treatment drove the formation of strätlingite (Ca 2Al 2SiO 7·8H 2O) and diminished availability of Si and Al for feldspathoid formation. Results indicate that pCO 2 and contaminant concentrations strongly affect contaminant speciation in waste-weathered sediments, and are therefore likely to impact reaction product stability under any remediation scenario.

Original languageEnglish (US)
Pages (from-to)119-127
Number of pages9
JournalJournal of Hazardous Materials
Volume197
DOIs
StatePublished - Dec 15 2011

Keywords

  • Cesium
  • Feldspathoids
  • Strontium
  • Strätlingite
  • Zeolite

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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