Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2003
Publication Date: 4/1/2003
Citation: FUHRMANN, M., LASAT, M.M., SCHWARTZ, M., EBBS, S.D., KOCHIAN, L.V., CORNISH, J. UPTAKE OF 137CS AND 90SR FROM CONTAMINATED SOIL BY THREE PLANT SPECIES: APPLICATION TO PHYTOREMEDIATION. JOURNAL OF ENVIRONMENTAL QUALITY. 2003. Interpretive Summary: Radionuclide contamination of soils poses serious problems to both human health and agriculture in the U.S. Soils have become contaminated with radionuclides as a result of above ground nuclear testing, accidental release or nuclear energy generation. 137Cs and 90Sr are long-lived by-products of nuclear fission. Although recent contamination of the environment with 137Cs and 90Sr from the testing of nuclear weapons has been drastically reduced, large areas are still polluted with radiocesium and strontium. The projected cost of cleaning up these radionuclide-contaminated soils is very high, in excess of 300 billion dollars. Phytoremediation is emerging as an attractive alternative to energy-intensive, high-cost traditional cleaning methods. This new technology employs the use of higher plants capable of accumulating high levels of contaminants in shoots. Following harvesting, the shoot biomass can be disposed of in a final repository after volume reduction (e.g., ashing). In this field study of a 137Cs and 90Sr contaminated site at the Brookhaven National Laboratory, 3 different plant species were grown to test their relative ability to extract radiocesium from the soil and accumulate it in the shoot. It was found that there were significant differences in radionuclide accumulating ability, with the species Amaranthus retroflexus able to accumulate about 40 times more 137Cs and 10 times more 90Sr than the other plant species. Based on these findings, it should be possible to use Amaranthus retroflexus to clean up this site from radiocesium contamination within 15-35 years.
Technical Abstract: A field test was conducted to determine the ability of three plant species to extract 137Cs and 90Sr from contaminated soil. Amaranthus retroflexus (L.), Brassica juncea (L.), and Phaseolus acutifolius (A. Gray) were planted in a series of spatially randomized cells in soil that was contaminated in the 1950's and 60's. We examined the potential for phytoextraction of 90Sr by plants and compared it to the accumulation of 137Cs by the same plants. Concentrations of 137Cs in these plants exhibited a linear relationship to their concentrations in the soil while 90Sr did not. Concentration ratios (CR) for 137Cs ranged from 0.2 to 2.6; for 90Sr they were substantially higher, ranging from 6.5 to 15.2. The greatest accumulation of both radionuclides was obtained with Amaranthus retroflexus (even though its CR for 90Sr was the lowest) because of its relatively large biomass. Estimates of times required for remocal of 50% of the two contaminants, assuming two crops of Amaranthus per year, are: 7 years for 90Sr and 18 years for 137Cs.