Just like hound dogs sniffing around for burglars, Closterium moniliferum, an green alga that usually lives in ponds, could sniff and eliminate radioactive strontium 90 (Sr-90) from water and from existing nuclear waste. 80 million gallons of radioactive nuclear waste are already stored in the United States. The discovery has been made by Northwestern University and Argonne National Laboratory researchers.
The algae sequester strontium by transforming it into harmless crystals of barium-strontium-sulfate. “Nuclear waste cleanup is a problem we have to solve,” said senior author Derk Joester, who experienced Chernobyl’s radioactive fallout when he was a teenager living in southern Germany. “Even if all the nuclear reactors were to shut down tomorrow, the existing volume of waste is great, and it is costly to store. We need to isolate highly radioactive ‘high-level’ waste from ‘low-level’ waste. The algae offer a mechanism for doing this, which we would like to understand and optimize.”
Strontium’s sinful chemical resemblance with calcium can make it dangerous to all living things, since it can infiltrate in bones and trigger cancer in a few years. The Closterium moniliferum is able to “tell” between calcium and strontium, though. Inside the cells, the algae first process barium, strontium and calcium from their watery environment. The calcium is excreted from the cells, and the other two are processed into crystals.
“The synchrotron X-ray microscopy available at the Advanced Photon Source was absolutely critical to this study,” Joester said. “It allowed us to visualize where calcium, strontium and barium go inside the cells.”
The team has only experimented with non-radioactive strontium, and hence it doesn’t know how these algae will behave in radioactive environments. It is believed that they’ll be able to cope with those, since they have already been seen surviving in harsh environments (they’re a kind extremophiles).
Cleaning up the mess after the Fukushima events could be greatly helped by this discovery. Also, the countless tons of radioactive residues around the world could have less impact on the environment and our health, and the nuclear industry could eventually become a bit safer.