Effect of biodegradable amendments on uranium solubility in contaminated soils.
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.
Duquène
L
L
Belgian Nuclear Research Centre, Environment Health and Safety, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
Tack
F
F
Meers
E
E
Baeten
J
J
Wannijn
J
J
Vandenhove
H
H
D001673:Biodegradation, Environmental; D002244:Carbon / Q000032:analysis; D002264:Carboxylic Acids / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012990:Soil Pollutants, Radioactive / Q000032:analysis / Q000737:chemistry*; D012995:Solubility; D014501:Uranium / Q000032:analysis / Q000737:chemistry*
D002264:Carboxylic Acids; D012990:Soil Pollutants, Radioactive; D014501:Uranium; D002244:Carbon