Feasibility of Phytoextraction to Clean Up Low-Level Uranium-Contaminated Soil

• Published in: International journal of phytoremediation Vol. 3; no. 3; pp. 301 - 320
• Main Authors: Vandenhove, Hildegarde, Hees, May Van, Winckel, Stefaan Van
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.01.2001
• Subjects: Amaranthus; Amaranthus retroflexus; Brassica juncea; citric acid; clean up; Indian mustard; Lolium perenne; phytoextraction; ryegrass; uranium
• ISSN: 1522-6514; 1549-7879
• DOI: 10.1080/15226510108500061

The potential to phytoextract uranium (U) from a sandy soil contaminated at low levels was tested in the greenhouse. Two soils were tested: a control soil (317 Bq 238 U kg -1 ) and the same soil washed with bicarbonate (69 Bq 238 U kg -1 ). Ryegrass (Lolium perenne cv. Melvina), Indian mustard (Brassica juncea cv. Vitasso), and Redroot Pigweed (Amarathus retroflexus) were used as test plants. The annual removal of the soil activity with the biomass was less than 0.1%. The addition of citric acid (25 mmol kg -1 ) 1 week before the harvest increased U uptake up to 500-fold. With a ryegrass and mustard yield of 15000 kg ha -1 and 10000 kg ha -1 , respectively, up to 3.5% and 4.6% of the soil activity could annually be removed with the biomass. With a desired activity reduction level of 1.5 and 5 for the bicarbonate washed and control soil, respectively, it would take 10 to 50 years to attain the release limit. A linear relationship between the plant 238 U concentration and the 238 U concentration in the soil solution of the control, bicarbonate-washed, or citric acid-treated soil points to the importance of the soil solution activity concentration in determining U uptake and hence to the importance of solubilising agents to increase plant uptake. However, citric acid addition resulted in a decreased dry weight production (all plants tested) and crop regrowth (in case of ryegrass).