Plant Uptake of Depleted Uranium from Manure-Amended and Citrate Treated Soil

Abstract

Six plant species were tested for their ability to accumulate depleted uranium in their above-ground biomass from deployed munitions contaminated soil in New Mexico. In greenhouse experiments, Kochia (Kochia scoparia L. Schrad.) and pigweed (Amaranthus retroflexus L) were grown with steer manure added at rates of 22.4, 44.8, and 89.6 Mg ha(-1). Citric acid and glyphosate (N-(phosphonomethyl) glycine) applied at the end of the growing season increased DU concentrations from 2.5 to 17 times. Leaf and stem DU concentrations in kochia increased from 17.0 to 41.9 mg kg(-1) and from 3.5 to 18.0 mg kg(-1), respectively. In pigweed, leaf and stem DU concentrations increased from 1.0 to 17.3 and from 1.0 to 4.7 mg kg(-1), respectively. Manure generally decreased or had no effect on DU uptake. The effect of citric acid and ammonium citrate on DU uptake by kochia, sunflower (Helianthus annuus L), and sweet corn (Zea mays L) was also studied. Ammonium citrate was just as effective in enhancing DU uptake as citric acid. This implies that the citrate ion is more important in DU uptake and translocation than the solubilization of DU through acidification. In both experiments, leaves had higher DU concentrations than stems.

Phytoremediation of Radionuclides: A Report on the State of the Art

“…Phytoremediation, which is also called as green remediation, botano-remediation, agroremediation or vegetative remediation is an emerging group of technologies utilizing green plants to clean up the environment from contaminants and has been offered as a simple and non-invasive alternative to the conventional engineeringbased remediation methods (El-Gendy 2008;Vandenhove et al 2009;Sevostianova et al 2010;Hoseinizadeh et al 2011). Soil is the ultimate and most important sink of chemical components in the terrestrial environment (Roy et al 2010).…”

Soil Ecosystem Responses to Depleted Uranium Contamination

“…These plants depend on chelating agents like citric acid to complex with uranium and render it more soluble and easy to take in. Otherwise, if the uranium remains insoluble then the plants cannot remove it from the soil system (Sevostianova et al, 2010). The relative bioavailability of uranium in soils remains generally low enough that non‐uranium‐loving plants can grow without undue hardship.…”

Fine scale measurement and mapping of uranium in soil solution in soil and plant-soil microcosms, with special reference to depleted uranium

“…In soil remediation trials, citric acid proved to be the most efficient amendment in solubilising U from soil (Duquène et al 2008;Huang et al 1998b) and in increasing its uptake by plants (Huang et al 1998b). Malic acid proved to be next most efficient (Huang et al 1998b;Sevostianova et al 2010). Although there is a change of soil solution pH of between 0.5 -1 units with the exudation of these acids (Huang et al 1998b), pH is not the only parameter affecting U solubility.…”

“…Although there is a change of soil solution pH of between 0.5 -1 units with the exudation of these acids (Huang et al 1998b), pH is not the only parameter affecting U solubility. Sevostianova et al (2010) recently found that citric acid and ammonium citrate had similar effects on plant uptake of U, implying that it is the citrate anion and not the change in pH that is most important in solubilising U. Citrate and malate both form complexes with uranium which both aids in the solubilisation of solid uranium minerals and in keeping uranium in solution (Huang et al 1998b;Kirishima et al 2008). At pH 6, uranium in oxidised solutions is mainly found in the form of uranyl hydroxide species while when citrate and malate are present at this pH or slightly lower, uranium is mainly complexed by them (Fox et al 2006;Krestou and Panias 2004).…”