Effect of biodegradable amendments on uranium solubility in contaminated soils

Sci Total Environ. 2008 Feb 25;391(1):26-33. doi: 10.1016/j.scitotenv.2007.10.042. Epub 2007 Dec 3.

Abstract

Chelate-assisted phytoextraction has been proposed as a potential tool for phytoremediation of U contaminated sites. In this context, the effects of five biodegradable amendments on U release in contaminated soils were evaluated. Three soils were involved in this study, one with a relatively high background level of U, and two which were contaminated with U from industrial effluents. Soils were treated with 5 mmol kg(-1) dry weight of either citric acid, NH(4)-citrate/citric acid, oxalic acid, S,S-ethylenediamine disuccinic acid or nitrilotriacetic acid. Soil solution concentration of U was monitored during 2 weeks. All amendments increased U concentration in soil solution, but citric acid and NH(4)-citrate/citric acid mixture were most effective, with up to 479-fold increase. For oxalic acid, S,S-ethylenediamine disuccinic acid and nitrilotriacetic acid, the increase ranged from 10-to 100-fold. The highest concentrations were observed 1 to 7 days after treatment, after which U levels in soil solution gradually decreased. All amendments induced a temporary increase of soil solution pH and TOC that could not be correlated with the release of U in the soil solution. Thermodynamic stability constants (log K) of complexes did not predict the relative efficiency of the selected biodegradable amendments on U release in soil solution. Amendments efficiency was better predicted by the relative affinity of the chelate for Fe compared to U.

MeSH terms

  • Biodegradation, Environmental
  • Carbon / analysis
  • Carboxylic Acids / chemistry*
  • Hydrogen-Ion Concentration
  • Soil Pollutants, Radioactive / analysis
  • Soil Pollutants, Radioactive / chemistry*
  • Solubility
  • Uranium / analysis
  • Uranium / chemistry*

Substances

  • Carboxylic Acids
  • Soil Pollutants, Radioactive
  • Uranium
  • Carbon