福島農地除去放射性物質實驗有結果

Recently the Mainichi News reported the following:
　農林水産省は１４日、福島県飯舘村などで５月から行っていた農地の放射性物質を除去する実証実験結果を発表した。農地の表面を３～４センチ削った場合はセシウムを７～９割減らせることが確認された。一方、放射性物質を取り込みやすいとされるヒマワリを植えてセシウムを吸収させる実験は効果が小さく、同省は「現時点での実用化は困難」とした。
　同省によると、５月に飯舘村で植えたヒマワリが吸収していたセシウムは１キロ当たり５２ベクレル程度。１平方メートル当たりで１０キロのヒマワリが育つとすると、現地の土壌中にあるセシウムのうち約２０００分の１しか吸収できていない計算になるという。
　一方で、表面４センチを削った農地では１キロ当たり１万３７０ベクレルから２５９９ベクレルまで減少。薬剤で土を固めてから表面（３センチ）をはぎ取ったり、芝や牧草がある農地で網目状に張った根ごと表面（同）をはぎ取るなど工夫すると８２～９７％も減った。
　ただし、これらの方式では１０アール当たり３０～４０トンの廃棄土砂が出る見込み。１キロ当たり５０００ベクレルを超える農地は福島県内に約８３００ヘクタールあると推計され、土砂は単純計算で約３５０万トン（東京ドーム２個分）に上り、処理方法が大きな課題となる。
(試譯文)
On the 14th, the Ministry of Agriculture, Forestry, and Fisheries released the actual proof of the experimental result on the removal of the radioactive material from the farmland, it was being performed since May in Iitate-mura of Fukushima and other locations.
When 3 to 4 cm of the surface of the farmland was removed, it was confirmed that the cesium could be reduced by 70-90 percent. On the other hand, the experiment on planting the sunflower which supposedly could easily taking in radioactive material and absorbing cesium, it had little effect, and the ministry supposedly said that "at this time it is difficult to have practical use."
According to the said ministry, the amount of cesium which the sunflower planted in Iitate-mura in May was absorbing was about 52 Bq per kilo. Supposed 10 kilo of sunflower were grown per square meter, it was said that the calculation showed that it could absorb only about 1/2000 of cesium existing inside the soil. On the other hand, in the farmland with 4 cm of surface removed, it decreases from 10,370 Bq per kilo to 2599 Bq. While stripping off the surface (3 cm) after hardening the ground with medicine, at the same time did the preparation work of removing the whole root that stretched in the shape of net meshes as seen in farmland that had pasture or grass, cesium decreased by no less than 82 to 97%.
However, by this method, for each 10 ares 30-40 tons of wasted earth would come out. If to estimate that in Fukushima there was about 8300 ha. of farmland with over 5000 Bq per km, then by simple calculation, the earth would go up to about 3,500,000 tons (two TOKYO DOME), and the method to dispose it would become a big subject.

It seems that to remove the top soil is the only way out.