In March 2011, following the magnitude 9.0 earthquake and tsunami, radioactive contaminants were released at the Japanese Fukushima Daiichi nuclear power facility. Since then, the radioactive contaminant cesium 137 (Cs-137) has been detected in the soil in areas surrounding the facility, and scientists have been exploring cost-effective ways to clean up the site that do more than just move the contaminates from one place to another or unintentionally create a chain reaction of contamination throughout the entire ecosystem.
Earthfort, a Corvallis-based agricultural company, has developed a biological soil additive that shows promise as a waste-free solution to decontaminating radioactive soils. Oregon State University students in nuclear engineering and radiation health physics are testing the bacteria Earthfort uses in their inoculant to determine how effectively it can immobilize Cs-137 and other longer-lived fission products in soil. Although the Cs-137 would not be removed using this solution, theoretically it would be rendered inert, because the bacteria Earthfort uses is not consumed by other organisms. If the laboratory experiments are successful, the additive will be used to mitigate soil contamination from the Fukushima nuclear crisis.
Graduating seniors Jenelle Parson, Michelle Comolli, Jesse Whitlow, and Matt Bensen developed an approach to test Earthfort’s inoculants by constructing soil columns designed to mimic the soil of Fukushima and then compared the transport of Cs-134 in inoculated, non-inoculated, and control columns. Over 28 days, the team applied Cs-134 in liquid form and came up with a watering mechanism to imitate rain and resultant groundwater. Clean groundwater would indicate that cesium will not be reintroduced to the food chain.
In preliminary results, the team discovered a three- to four-fold reduction in the amount of cesium leached from inoculated soil. As they continue to analyze results, another group of students is analyzing Cs-134 uptake by radishes via water passed through inoculated and non-inoculated soil.