To what extent did the nuclear tests in the 20th century affect the planet? Evidently, even the creatures at the Mariana Trench have remnants of radioactive carbon in their muscles.

Radioactive Carbon

Thermonuclear weapons tests during the 1950s and 1960s increased the amount of carbon-14 in the atmosphere, with levels peaking during the mid-1960s, and then dropping once the tests were halted. By the 1990s, the levels were at 20 percent above the previous levels before the testing began, but the so-called bomb carbon then fell out of the atmosphere and into the oceans.

In a new study, researchers found the first evidence of radioactive carbon in the deepest parts of the Earth’s oceans. By testing the amphipods that they collected from the Mariana, New Britain, and Mussau Trenches in 2017, researchers found traces of carbon-14 in the creatures’ muscle tissues, at levels that are much greater than the levels found in deep ocean water.

Deep Ocean Contamination

Deep ocean creatures feed on the bodies of the creatures living closer to the ocean surface. Unfortunately, the bodies from closer to the surface have had traces of bomb carbon since the 1950s, which means that when the deep ocean creatures feed on them, they also ingest the contamination.

What's interesting is that the creatures that they tested are actually larger and live longer than their shallow water counterparts, likely as an adaptation to the harsh environment in which they live in. This could mean that the longer life leads to a higher accumulation of the pollutants in the creatures’ bodies, thereby threatening the remote ecosystems they live in.

Human Activity

Unfortunately, the results of the study show just how deeply human activity can affect the planet, so much so that it can reach the deepest trenches in the planet in just a short amount of time. Generally, the contamination in the water itself takes hundreds of years to reach the deep trenches, but because of the food chain, the contamination is happening quicker.

“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 of the Chinese Academy of Sciences, coauthor of the study.

The study is published in Geophysical Research Letters.