The radioactive carbon created as a byproduct of nuclear bomb testing has reached the deepest parts of the ocean and is ending within marine creatures.
This finding by Chinese researchers shows how quickly human contamination can enter the food chain and find its way to the depths of the ocean.
However, this carbon bomb is helping scientists learn more about how marine life manages to survive in such cold, dark, deep and nutrient-poor environments.
They found that small marine crustaceans can live much longer than their shallow water counterparts and grow to a much larger size.
This is likely because animals have developed extremely slow metabolisms as an adaptation to living in the extreme conditions found in deep ocean trenches.
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The radioactive carbon created as a by-product of previous nuclear bomb tests (in the image, archive image) has reached the deepest parts of the ocean, and is ending within marine creatures
Researchers led by the geochemist of the Chinese Academy of Sciences, Ning Wang, used carbon traces of nuclear bombs to badyze deep-water amphipods, small marine crustaceans that live in the collection of dead organisms and marine debris.
The animals were collected in 2017 from three trenches in the western Pacific Ocean, Mariana, Mussau and New Britain, to depths of up to 7 miles (11 kilometers) below the surface of the ocean.
Experts were surprised to find that the carbon-14 levels in amphipod muscles were much higher than those found in the organic matter that floated in deep water.
When badyzing the content of the animal's casings, they found that the levels of carbon derived from the pump were also high and coincided with the levels of carbon-14 found in organic materials near the surface of the Pacific Ocean.
These findings suggest amphipods selectively feed on the debris that has fallen to the seafloor from the surface of the ocean, instead of absorbing the most local sources of carbon deposited in nearby sediments.
"Although ocean circulation takes hundreds of years to carry water with a pump [carbon] "In the deepest ditch, the food chain accomplishes this much more quickly," said Ms. Wang.
The findings are helping researchers understand how creatures such as amphipods have adapted to live in the deepest parts of the ocean, which are more than 6 kilometers (4 miles) below the surface of the ocean, in which it is known as the hadal zone.
The deep chasms are only found within the ocean trenches, narrow depressions in the shape of the seabed that form where one of the tectonic plates of the Earth subducts beneath another.
The animals that call these trenches home must adapt to live under intense pressures and extremely cold temperatures, as well as to be able to cope with the lack of available light and nutrients.
Ms. Wang and her colleagues discovered that the amphipods that live in these three deep ocean trenches tend to grow more and live longer than their counterparts.
The researchers used traces of carbon from nuclear bombs to badyze the amphipods (pictured), small marine crustaceans that live by eliminating dead organisms and marine debris.
The amphipods that live in shallow waters usually live less than two years and reach an average length of about 0.8 inches (2 centimeters).
However, the researchers found that amphipods in the deep ocean trenches were more than 10 years old and 3.6 inches (9.1 centimeters) long.
Scientists believe that the size and longevity of deep-living amphipods can be attributed to the same evolutionary adaptations that allow them to live in such a cold, high-pressure, and nutrient-poor environment.
A slow metabolism and a low rate of cell replacement would allow small crustaceans to store energy for long periods of time.
However, this same longevity would also mean that contaminants have the opportunity to accumulate at higher levels in these unusual creatures.
This & # 39; bring[s] "More threats to the most remote ecosystems," Wang said.
The amphipods were collected in three trenches in the western Pacific Ocean, Mariana, Mussau and New Britain, to depths of up to 7 miles (11 kilometers) below the surface of the ocean.
& # 39; There is a very strong interaction between the [ocean] surface and background, in terms of biological systems, co-author of the added article Weidong Sun, who is a geochemist at the Chinese Academy of Sciences in Qingdao.
"Human activities can affect biosystems even at 11,000 meters, so we must be careful with our future behaviors." he said.
"It is not expected, but it is understandable, because it is controlled by the food chain."
"What's really new here is not just that the carbon from the surface of the ocean can reach the depths of the ocean at relatively short time scales," said Rose Cory, an Earth scientist at the University of Michigan who was not involved in the study. the study.
Instead, he continued, the main novelty lies in how the young carbon professionalDuchy on the surface of the ocean is feeding or sustaining life in the deepest trenches, & # 39; Csaid Ory.
The full findings of the study were published in the journal Geophysical Research Letters.
WHAT IS CARBON 14?
Carbon-14 is produced by nuclear tests, like this one, in Nevada, in 1957.
Carbon-14 is a radioactive isotope of carbon.
It is much less common than its non-radioactive counterpart.
Both forms of carbon are found in living organisms, albeit in different amounts.
The experts use the two isotopes together to calculate the ages of the archaeological and geological samples.
Carbon-14 is created naturally when cosmic rays interact with nitrogen in the atmosphere.
But it can also be created artificially as a product of nuclear explosions, when neutrons released by atomic bombs collide with atmospheric nitrogen.
Tests of nuclear weapons in the 50s and 60s saw that carbon-14 levels in the atmosphere doubled temporarily.
Levels fell rapidly when tests stopped and, by the 1990s, had returned to only 20 percent above their pre-pump amounts.
Carbon bomb from the atmosphere fell to the surface of the ocean.
Here, it has been absorbed by marine creatures and incorporated into their bodies.
As a result, scientists began finding higher carbon-14 levels in marine creatures shortly after the first bomb tests began.