https://news.v.daum.net/v/20190515103305725?fbclid=IwAR28YaLcAjWGC9lGTtP4LAoxlRUdNyV5nJ3hl50Tp2QtTVIS4-TdKOivY8Q Until now, it has been unclear whether bomb carbon has managed to spread into the farthest crevices of the world, especially the deepest seas. It would have taken natural oceanic circulation about 1,000 years to carry it to the depths of the Mariana Trench.
And in fact, testing for the new study showed that the waters of the trench did have low levels of carbon-14—which is what the researchers expected, given the long travel time from atmosphere to deep ocean.
But when they used traps to catch and test crustaceans living at these depths, they detected much higher levels of the isotope in these animals’ tissues and gut contents than in the surrounding waters.
The bomb carbon had to be arriving another way that brought it there faster, and the researchers surmised it was taking a shortcut via the food chain. Organic matter—including the poop and carcasses of surface-dwelling life—falls through the water column in just weeks or months.
When crustaceans on the seabed munch these morsels, they absorb the signature of nuclear tests into their bodies, the researchers say in their study, published online in April in Geophysical Research Letters [pdf].
Other studies conducted around the world have also recently identified the residue of the weapons tests of the mid-20th century—as well as the Chernobyl and Fukushima nuclear disasters—in mountain glaciers, another landscape often considered pristine and remote. Together with the results from the Mariana Trench, these findings “prove that atmospheric and oceanic circulation distribute bomb-derived radioactivity globally, even to the most remote sites,” says Edyta Lokas of the Institute of Nuclear Physics PAS in Krakow, Poland, who worked on the glacier research, which was presented at a meeting of the European Geoscience Union (EGU) in April. Worse still, the fallout locked in glaciers includes more worrisome radioactive elements (such as americium-241, a product of the decay of plutonium)—and could be released as the world warms and the ice thaws.
“The legacy of radioactive contamination will be felt by many generations ahead,” Lokas says.
https://www.scientificamerican.com/article/bomb-carbon-has-been-found-in-deep-ocean-creatures/?redirect=1
