FURTHER EVALUATIONS OF RADIONUCLIDE PHYTOEXTRACTION FEASIBILITY USING SOILS FROM THE U.S. DEPARTMENT OF ENERGY COMPLEX
Fiscal Year 98 (FY98) radionuclide phytoextraction studies involved resumption of the radiocesium-137 ({sup 137}Cs) investigations at Brookhaven National Laboratory (BNL) and the total uranium (U{sub t}) investigations at the Fernald Environmental Management Project (FEMP) site. This project was a collaborative effort involving scientists and engineers from MSE Technology Applications, Inc.; the US Department of Agriculture (USDA) Plant Growth Laboratory at Cornell University; Phytotech, Inc.; BNL; and FEMP. In both cases, the essential goal was to improve bioavailability, uptake, and transport of these contaminants from soil to leaf-and-stalk biomass (LSB). In particular, the practical goal was to demonstrate that about half the radionuclide contaminant mass present in near surface [{le}30 centimeters (cm) below ground surface (bgs)] soils could be transferred into LSB in approximately 5 years. Based on previous (1996) study results, it would require concentration ratios (CRs) of at 5-to-10 to achieve this goal. In addition, the rate of {sup 137}Cs removal must be {ge} 2.3% per year{sup -1} [i.e., (0.693/30.2) {center_dot} 100] to equal or exceed the loss of this radionuclide through natural decay. This report first presents and discusses the results from greenhouse and field evaluations of {sup 137}Cs uptake from rooting zone soils (0-15 cm bgs) located near the Medical/Biological Research Building (No. 490) at BNL. Contamination of this site resulted from the use of near surface soils originating at the former Hazardous Waste Management Facility (HWMF), which served as a source of landscaping materials for erosion control, etc. Project personnel from USDA evaluated various combinations of nonradioactive solutions of cesium chloride (CsCl) and rubidium chloride, ammonium nitrate solution (NH{sub 4}NO{sub 3}), and humic acid suspensions to enhance and sustain {sup 137}Cs levels in soil solution. Of the plants grown in such amended soils, the highest CRs occurred in the golden pigweed (Amaranthus aureus L.) with an overall CR of 3.0 (and 275 picoCurie/gram {sup 137}Cs in soil). The maximum CR (3.8) was associated with dosing this species with 100 millimole (mM) CsCl solution. However, this treatment was immediately toxic to all the species evaluated. Thus, continued use of ammonium nitrate (NH{sub 4}NO{sub 3}) (CR=2.9) or humic acid (CR=3.2) and golden pigweed appeared to be the best approach for removing {sup 137}Cs from test site soils.
- Research Organization:
- Department of Agriculture (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- AI22-95PC95701
- OSTI ID:
- 835034
- Resource Relation:
- Other Information: PBD: 1 Jan 1999
- Country of Publication:
- United States
- Language:
- English
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