Lead Phytoextraction from Contaminated Soil with High-Biomass Plant Species

Lead Phytoextraction from Contaminated Soil with High-Biomass Plant Species,10.2134/jeq2002.1893,Journal of Environmental Quality,Zhen-Guo Shen,Xiang-

Lead Phytoextraction from Contaminated Soil with High-Biomass Plant Species   (Citations: 86)
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can be cultivated to reduce the concentrations of heavy metals in contaminated soils to environmentally accept- In this study, cabbage (Brassica rapa L. subsp. chinensis (L.) Ha- able levels (Raskin et al., 1994). Heavy metals can be nelt cv. Xinza No 1), mung bean (Vigna radiata (L.) R. Wilczek var. radiata cv. VC-3762), and wheat (Triticum aestivum L. cv. Altas 66) translocated to aboveground plant parts. The metal-rich were grown in Pb-contaminated soils. Application of ethylenedi- plant material may be safely harvested and removed aminetetraacetic acid (EDTA) (3.0 mmol of EDTA/kg soil) to the from the site without extensive excavation, disposal soil significantly increased the concentrations of Pb in the shoots and costs, and loss of topsoil associated with traditional re- roots of all the plants. Lead concentrations in the cabbage shoots mediation practices (Blaylock et al., 1997). reached 5010 and 4620 mg/kg dry matter on Days 7 and 14 after The success of a phytoremediation process is depen- EDTA application, respectively. EDTA was the best in solubilizing dent on adequate plant yield and high metal concentra- soil-bound Pb and enhancing Pb accumulation in the cabbage shoots tions in plant shoots. Plants must produce sufficient among various chelates (EDTA, diethylenetriaminepentaacetic acid biomass while accumulating high concentrations of (DTPA), hydroxyethylenediaminetriacetic acid (HEDTA), nitrilotri- heavy metals. Hyperaccumulator plants possess an abil- acetic acid (NTA), and citric acid). Results of the sequential chemical extraction of soil samples showed that the Pb concentrations in the ity to take up abnormally high amounts of heavy metals carbonate-specifically adsorbed and Fe-Mn oxide phases were signifi- in their shoots (Chaney et al., 1997; Shen et al., 1997). cantly decreased after EDTA treatment. The results indicated that However, most hyperaccumulator species are not suit- EDTA solubilized Pb mainly from these two phases in the soil. The able for phytoremediation application in the field due relative efficiency of EDTA enhancing Pb accumulation in shoots to their small biomass and slow growth. As an alterna- (defined as the ratio of shoot Pb concentration to EDTA concentra- tive, it has been suggested to use high biomass species, tion applied) was highest when 1.5 or 3.0 mmol EDTA/kg soil was such as maize (Zea mays L.), pea (Pisum sativum L.), used. Application of EDTA in three separate doses was most effective oat (Avena sativa L.), canola (Brassica napus L.), barley in enhancing the accumulation of Pb in cabbage shoots and decreased (Hordeum vulgare L.), and Indian mustard (Brassica mobility of Pb in soil compared with one- and two-dose application juncea (L.) Czern.), with improved plant husbandry and methods. This approach could help to minimize the amount of chelate applied in the field and to reduce the potential risk of soluble Pb soil management practices to enhance metal uptake by movement into ground water.
Journal: Journal of Environmental Quality - J ENVIRON QUAL , vol. 31, no. 6, 2002
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