Iodine-131 and cesium-134/137 are radioactive isotopes that have been released from the Fukushima Daiichi Nuclear Power Plant as a consequence of the 2011 earthquake and tsunami that hit Japan. Large amounts of this radioactive material have gone into the Pacific Ocean. That’s the bad news.

The good news is that scientists at the University of Tsukuba in the Kantō region of Japan have tested 189 species of algae and have identified some able to absorb cesium-137. Initial results are very encouraging: contaminated water can be purified as much as 40% to 70% by the algae with the greatest cleansing power. The purifying seaweed is removed from the water, filtered and burned. The idea is to apply this technique more widely to decontaminate lakes, rice paddies and other water sources.