How sunflowers were used to clean up Fukushima

The Tweet: “Sunflowers can be used to clean up radioactive waste.”

In the aftermath of the Chernobyl disaster hundred of thousands of inhabitants were relocated and the town was left uninhabitable. However, in the case of Fukushima the Japanese government is hoping to make the area liveable again for the 80,000 displaced residents, and to do so, they’re turning to plants.

Contamination of groundwater poses a serious environmental problem by spreading radioactive elements beyond the initial disaster zone into inhabited areas of farmland. Part of the problem with trying to clean up the land after radioactive fallout is that contaminant particles are spread thinly across large areas of land. In some cases the authorities have resorted to bulldozing topsoil from playgrounds and parks, but doing this requires disposing of large quantities of contaminated soil.

The solution is to use plants to extract the radioactive particles from the soil on behalf of the scientists. This was trialled in the aftermath of Chernobyl with some success and researchers in Japan are hoping that by using plants early on in the operation they can achieve even better successes.

Speaking to Japan Today, soil scientist Michael Blaylock, who worked on the Chernobyl clean up, explains how plants are able to clean radioactive elements from the soil: “Those radioisotopes mimic some of the nutrients that the plant takes up normally. And so the plant really doesn’t distinguish between those radioactive isotopes and some of the nutrients like potassium and calcium that it takes up as a matter of course.”

Blaylock hopes that by being better prepared to use sunflowers could mean that the area around Fukushima will be inhabitable sooner than Chernobyl. “One thing we found in Chernobyl is, we came there a number of years after the fact. And so that gave plenty of time for that caesium to become fixed in the soil,” he said, adding, “Sunflowers are attractive because they grow well and produce a lot of biomass quickly. It doesn’t take a lot of management to grow sunflowers as compared to some other crops; they are adaptable to a lot of different climates.”

“What we’re trying to do is concentrate that radioactivity from the soil, which is a fairly low concentration, to a much higher concentration in the plant material. You still have to dispose of that plant material [but] you have a lot less material to dispose of, and you can leave that soil, which is a resource that’s hard to replace – you can leave that soil in place and just remove the contaminant.”

The success isn’t limited to soil. Sunflowers grown in floating containers were able to remove 90% of contaminants from ponds in the Chernobyl trials. Fungi and algae have also been used. In October 2011, a species of green algae remove 80% of radioactive strontium and 40% of caesium in just 10 minutes when painted onto roads and walls in the Fukushima plant.

Image: TexasEagle/ Flickr