Banned pollutants discovered in deepest reaches of our oceans

14 Feb 2017478 Views

Image: Shutterstock/Underworld

A new study spanning the depths of Earth’s oceans has found human-made pollutants that were banned in the 1970s – and they’re deeper into the food chain than we thought.

Two of the deepest parts of the Pacific Ocean are home to man-made pollutants, as the 10,000km-deep Marianas and Kermadec trenches show humanity’s grubby fingerprints throughout.

Although separated by 7km of ocean, the two trenches exhibit the same signs of human interference, as noted by UK researchers who investigated the deep, dark home of several bizarre creatures.


Sampling amphipods from the Marianas and Kermadec trenches, Newcastle University’s Dr Alan Jamieson led a study that found extremely high levels of pollution in the organism’s fatty tissue.

These included polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), pollutants commonly used as electrical insulators and flame retardants.

The former was banned in the 1970s in many parts of the world, which means that during its four-decade run, enough PCB was produced – estimated at 1.3m tonnes – to have a potentially damaging impact 40 years later.

‘The fact that we found such extraordinary levels of these pollutants … really brings home the long-term, devastating impact that mankind is having on the planet’

“We still think of the deep ocean as being this remote and pristine realm, safe from human impact, but our research shows that, sadly, this could not be further from the truth,” said Jamieson.

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“In fact, the amphipods we sampled contained levels of contamination similar to that found in Suruga Bay, one of the most polluted industrial zones of the north-west Pacific.

“What we don’t yet know is what this means for the wider ecosystem, and understanding that will be the next major challenge.”

Last year, a team of researchers sent a drone deep down into Marianas Trench to investigate unknown forms of sea life. Among the findings was a jellyfish at a depth of around 3,700ft, in what is aptly called the Enigma Seamount.

It took a few viewings for us to believe this was not doctored, such is the colour make-up of the jelly.

Today’s study suggests that the pollutants found their way to the trenches through contaminated plastic debris and dead animals sinking to the bottom of the ocean, where they are then consumed by amphipods and other fauna, which in turn become food for larger fauna.

“The fact that we found such extraordinary levels of these pollutants in one of the most remote and inaccessible habitats on earth really brings home the long-term, devastating impact that mankind is having on the planet,” said Jamieson.

“It’s not a great legacy that we’re leaving behind.”

Gordon Hunt is senior communications and content executive at NDRC. He previously worked as a journalist with Silicon Republic.