Using Plants To Detect Tritium Contamination

Plant foliage samples being placed in direct sunlight for water extraction by solar distillation. Water vapor released from the foliage condenses as liquid on the inside surface of the sample bag. (Click on photo for larger version)

USGS scientists have developed a new cost-effective method for identifying the occurrence and distribution of tritium contamination in the subsurface that uses plants as "tritium detectors." Desert plants efficiently scavenge for water in the soil root-zone, and if the water contains tritium the tritium is absorbed along with the water. As a result, the concentration of tritium in the water in plants is correlated to the concentration of tritium in the soil water on which the plants rely for survival. Thus, the plants can be used to rapidly assess and map the size and shape of tritium plumes in the shallow unsaturated zone at contaminated sites.

The method involves collecting plant foliage samples followed by solar distillation of the leaves in plastic bags on site to collect plant water. The collected water is taken to the laboratory and processed to remove constituents that can interfere with subsequent tritium analysis. The simplified method is of sufficient accuracy to facilitate optimized placement of more sophisticated (and costly) monitoring equipment. The new method is also a time saver! Collection and preparation of samples can be done in one-fourth the time required by the standard chemical-extraction method or by soil-gas sampling.

The method is based on research that USGS scientists conducted at the Amargosa Desert Research Site (ADRS) on the importance of plants in the water balance and the movement of water in the deep (110-meter-thick at the ADRS) unsaturated zones of deserts in the southwestern United States. This method is one more tool that will help scientists provide resource managers with the information needed to make informed decisions about waste disposal in arid environments. Deserts are often candidates for waste disposal because of their unique characteristics and lack of water.

More Information

• Simplified method for detecting tritium contamination in plants and soil: Andraski, B.J., Sandstrom, M.W., Michel, R.L., Radyk, J.C., Stonestrom, D.A., Johnson, M.J., and Mayers, C.J., 2003, Journal of Environmental Quality, v. 32, p. 988-995.
• Importance and Use of Plants in Evaluating Water Flow and Contaminant Transport in Arid Environments: B.J. Andraski, M.W. Sandstrom, R.L. Michel, J.C. Radyk, D.A. Stonestrom, M.J. Johnson, and C.J. Mayers, A poster presented at the American Geophysical Union's Fall 2002 Meeting, December 6-10, 2002
• Desert Plants Reveal Contaminant Transport Pathways, (2005 Headline on the application of the method)
• Photo Gallery, Simplified method for detecting tritium contamination in plants and soil
• Amargosa Desert Research Site
  

Related Headlines

• New Model Allows for More Accurate Simulation of Tritium Movement in the Unsaturated Zone
• Widespread Accumulations of Natural Perchlorate in Southwestern Soils
• New Model Improves Understanding of the Transport of Carbon Isotopes in the Unsaturated-Zone
• High Nitrate in the Desert? What's Going On?
• Are Deserts Still Drying Out Since the Ice Age?
• New Book on Soil Analysis Methods Destined to Become a Classic
• Phytoremediation in the Desert?
• Alternative Landfill Cover Assessment

Back to Headlines Page