Sunflowers Fail to Decontaminate Radioactive Soil
Several months ago, optimistic news stories appeared about how people were planning to plant thousands of sunflowers in an effort to decontaminate areas around the Fukushima Daiichi nuclear power plant:
Fifty kilometres away from the plant site the Buddhist Joenji temple. There, chief monk Koyu Abe and a team of 100 volunteers began growing and distributing sunflowers, hoping to both lift spirits and lighten the radiation’s impact.
“We plant sunflowers, field mustard, amaranthus and cockscomb, which are all believed to absorb radiation,” said the monk. “So far we have grown at least 200,000 flowers (at this temple) and distributed many more seeds. At least 8 million sunflowers blooming in Fukushima originated from here.”
Scientists are currently testing the effectiveness of sunflowers used to battle radiation.
Results from testing are now becoming available, and, unfortunately, it seems that sunflowers are not a very good option:
The sunflowers that the ministry had planted in Iitate in May had absorbed around 52 becquerels of cesium per kilogram, according to the ministry. Even if sunflowers worth 10 kilograms were grown per square meter of farmland, only about 1/2000th of cesium in the soil could be absorbed, the ministry said.
The topsoil removal method, on the other hand, proved to be highly effective, with radioactive cesium in the soil plunging from 10,370 becquerels to 2,599 becquerels per kilogram after three to four centimeters of the topsoil was scraped off.
The method becomes even more effective when the topsoil is hardened by pharmacological agents before being removed, or when the topsoil was taken away all together with grass roots. Both methods could reduce levels of cesium by 82 to 97 percent.
While the topsoil removal method seems to be extremely effective, it will be quite difficult to implement. Digging up that much land will require a lot of labor, and authorities will have to find some place to store tons of contaminated dirt.