The shells of chelonians—think turtles, tortoises, and sea turtles—grow in layers, keeping a time-stamped record of environmental conditions.
Uranium has shown up in the layers of turtles’ and tortoises’ shells in various locations known for nuclear activity.
Scientists suggest that turtles in areas known for nuclear activity could prove valuable for use in long-term environmental monitoring programs.
Humans may call for saving the turtles, but the turtles may end up doing their part to save us. Or, at least, keep us apprised of potentially unsafe conditions. Scientists have found that chelonians—turtles, tortoises, and sea turtles—can retain uranium contamination in the layers of their shells, saving up a wealth of environmental information.
In a study published in the journal PNAS Nexus, researchers claim that the scute keratin of a chelonian shell layers over time. “Scute keratin acts as an inert reservoir of environmental information,” the authors wrote. And for any chelonian living near active modern nuclear sites, those shells “act as a time-stamped record of radionuclide contamination of the environment.”
The scientists from the University of New Mexico and Los Alamos National Laboratory—locations that know a thing or two about nuclear, as Los Alamos was the birthplace of the atomic bomb—studied samples of chelonian scute from areas known to have experienced nuclear activity or nuclear waste storage.
That drove scientists to seek out some sea turtle shells from the Republic of the Marshall Islands, a desert tortoise from the Barr M. Goldwater Air Force Range in southwestern Utah, a river cooter turtle from South Carolina’s Savannah River Site, and a box turtle from the Oak Ridge Reservation in eastern Tennessee.
“We identify legacy uranium contamination in bulk and sequential chelonian scute that matches known nuclear histories at these locations during the 20th century,” the authors wrote. “Our results confirm that chelonians bioaccumulate uranium radionuclides and do so sequentially over time.”
The shell signatures were so exacting that the scientists could map out the rise in activity at each site, including when it peaked, like one could gather data from the rings of a tree.
And even when the shell’s owner wasn’t alive at the time of the intense activity, the polluted legacy lived on. A green sea turtle shell pulled from inside a captured tiger shark near the Enewetak Atoll in 1978, though it was not present during the intense atomic bomb testing nearby decades before, still showed off uranium contamination.
The power of the shell lives on. “This technique provides both a time series approach for reconstructing nuclear histories from significant past and present contexts throughout the world and the ability to use chelonians for long-term environmental monitoring programs,” the authors wrote.
They go so far as to propose that we drop some sea turtles into Enewetok and swimsuit Atolls in the Marshall Islands, and possibly add a few more near the Fukushima reactor to get the monitoring going.
Hopefully, the turtles can keep us even a little safer in the future.
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