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.
Belgian Nuclear Research Centre, Environment Health and Safety, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
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L
Duquène
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F
Tack
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E
Meers
J
J
Baeten
J
J
Wannijn
H
H
Vandenhove
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