Tall and a cheery yellow hue, sunflowers are among the most iconic flowers in the world. Their bright heads track the sun across the sky, offering a spirit-lifting vista for humans and nourishment for a host of wildlife: bees, butterflies, birds and small mammals all rely on the seeds and nectar for survival.
Beyond supporting ecosystems, sunflowers harbour a surprising superpower: they can absorb toxins from the soil and water, including radioactive isotopes left behind by nuclear disasters.
In places such as Fukushima, Japan and Chernobyl, Ukraine, these everyday blooms have been planted in an extraordinary effort to detoxify the environment.
What happened at Chernobyl and Fukushima?
The Chernobyl disaster took place on April 26, 1986, and remains the world’s worst nuclear accident. An explosion in a reactor spread radioactive material across Ukraine, Belarus and beyond.
In March 2011, a magnitude 9.0 earthquake struck Japan, triggering a massive tsunami that devastated the state of Fukushima. The Fukushima Daiichi nuclear plant suffered explosions, releasing radioactive material into the environment.
Both events had a massive impact on biodiversity.
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The cleaning power of sunflowers
Amid the cleanup efforts in Chernobyl, one unusual solution was planted in fields – sunflowers. Sunflowers are used in a process known as phytoremediation – plants removing toxins from soil and water.
Radioactive cesium and strontium had polluted soil and water. As soil scientist Michael Blaylock explains to environmental news site, Living on Earth: “Sunflowers are really good at taking up certain radioactive isotopes … some of the fallout from the Chernobyl accident we were able to address through planting sunflowers in the affected areas.
“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.”
The technique works well for strontium in soil. “Cesium in soil is a little bit tricky,” Blaylock goes on to explains. Soils that have very high mica contents, certain clays, are difficult to remove the cesium from once it gets fixed.”
Though the sunflowers helped with waterborne isotopes, the soil remained largely unchanged – although it saved large amounts of radioactive water and soil being collected and disposed of.
Still, local residents were encouraged to help with the planting and collecting of hundreds of thousands of sunflowers, which are fast-growing and resilient and absorb the radioactive elements up into the plant rather than roots, allowing for them to be removed easily.
These efforts were also repeated by those living nearby radioactive hot spots in Fukushima.
While no conclusive evidence supports the success rate of sunflowers removing radioisotopes, phytoremediation is increasingly being used as a method to tackle soil contamination – a critical environmental challenge.
Main image: Sunflower field in Sannokura plateau, Japan. Credit: Getty Images
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