In the joint study by the University of Tokyo and Fukushima Prefecture, home to the TEPCO plant, cesium that fell onto rice paddies at the Fukushima Agricultural Technology Center in the city of Koriyama seeped into the ground at speeds 0.1 to 0.2 times the penetration speed of water, compared with the previously estimated level of 0.001 times
The university and the prefecture also looked at the strength of fixation between cesium and soil particles.
Cesium-tainted soil samples from the center were poured into fresh water and water containing fertilizers, and these were stirred for a while. But only 20 pct of the cesium contained in the soil samples dissolved into the water, while the rest remained stuck to soil particles.
The result indicates that it is difficult to wash cesium away from crop fields and rice paddies.