nuclear-news

Radioactive carbon from nuclear bomb tests found in deep ocean trenches, Phys Org, by American Geophysical Union 8 May 19, Radioactive carbon released into the atmosphere from 20th-century nuclear bomb tests has reached the deepest parts of the ocean, new research finds.A new study in AGU’s journal Geophysical Research Letters finds the first evidence of radioactive carbon from nuclear bomb tests in muscle tissues of crustaceans that inhabit Earth’s ocean trenches, including the Mariana Trench, home to the deepest spot in the ocean.

Organisms at the ocean surface have incorporated this “bomb carbon” into the molecules that make up their bodies since the late 1950s. The new study finds crustaceans in deep ocean trenches are feeding on organic matter from these organisms when it falls to the ocean floor. The results show human pollution can quickly enter the food web and make its way to the deep ocean, according to the study’s authors.

“Although the oceanic circulation takes hundreds of years to bring water containing bomb [carbon] to the deepest trench, the food chain achieves this much faster,” said Ning Wang, a geochemist at the Chinese Academy of Sciences in Guangzhou, China, and lead author of the new study.

“There’s a very strong interaction between the surface and the bottom, in terms of biologic systems, and human activities can affect the biosystems even down to 11,000 meters, so we need to be careful about our future behaviors,” said Weidong Sun, a geochemist at the Chinese Academy of Sciences in Qingdao, China, and co-author of the new study. “It’s not expected, but it’s understandable, because it’s controlled by the food chain.”……

Thermonuclear weapons tests conducted during the 1950s and 1960s doubled the amount of carbon-14 in the atmosphere when neutrons released from the bombs reacted with nitrogen in the air. Levels of this “bomb carbon” peaked in the mid-1960s and then dropped when atmospheric nuclear tests stopped. By the 1990s, carbon-14 levels in the atmosphere had dropped to about 20 percent above their pre-test levels.

This bomb carbon quickly fell out of the atmosphere and mixed into the ocean surface. Marine organisms that have lived in the decades since this time have used bomb carbon to build molecules within their cells, and scientists have seen elevated levels of carbon-14 in marine organisms since shortly after the bomb tests began……..https://phys.org/news/2019-05-radioactive-carbon-nuclear-deep-ocean.html