Presence of man-made chemicals in most remote place on planet shows nowhere is safe from human impact, say scientists.
Scientists have discovered “extraordinary” levels of toxic pollution in the most remote and inaccessible place on the planet – the 10km deep Mariana trench in the Pacific Ocean.
Small crustaceans that live in the pitch-black waters of the trench, captured by a robotic submarine, were contaminated with 50 times more toxic chemicals than crabs that survive in heavily polluted rivers in China.
“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 Alan Jamieson of Newcastle University in the UK, who led the research.
“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,” he said.
Jamieson’s team identified two key types of severely toxic industrial chemicals that were banned in the late 1970s, but do not break down in the environment, known as persistent organic pollutants (POPs). These chemicals have previously been found at high levels in Inuit people in the Canadian Arctic and in killer whales and dolphins in western Europe.
The research, published in the journal Nature Ecology and Evolution, suggests that the POPs infiltrate the deepest parts of the oceans as dead animals and particles of plastic fall downwards. POPs accumulate in fat and are therefore concentrated in creatures up the food chain. They are also water-repellent and so stick to plastic waste.
He said it was not unexpected that some POPs would be found in the deepest parts of the oceans: “When it gets down into the trenches, there is nowhere else for it to go. The surprise was just how high the levels were – the contamination in the animals was sky high.”
. . . The results are both significant and disturbing, said the marine ecologist Katherine Dafforn at the University of New South Wales in Australia and not part of the research team: “The trenches are many miles away from any industrial source and suggests that the delivery of these pollutants occurs over long distances despite regulation since the 1970s.
“We still know more about the surface of the moon than that of the ocean floor,” Dafforn said. She said the new research showed that the deep ocean trenches are not as isolated as people imagine. “Jamieson’s team has provided clear evidence that the deep ocean, rather than being remote, is highly connected to surface waters. Their findings are crucial for future monitoring and management of these unique environments.”
POPs cause a wide range of damage to life, particularly harming reproductive success. Jamieson is now assessing the impact on the hardy trench creatures, which survive water pressures equivalent to balancing a tonne weight on a fingertip and temperatures of just 1C.
He is also examining the deep sea animals for evidence of plastic pollution, feared to be widespread in the oceans, which has been the focus of much recent attention, leading to bans on plastic microbeads in cosmetics in the UK and US. “I reckon it will be there,” he said. . . .
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‘Extraordinary’ levels of pollutants found in 10km deep Mariana trench
By Damian Carrington, The Guardian
March 13, 2017
. . . The researchers, from the University of Aberdeen and the James Hutton Institute in the U.K., focused on two specific types of chemical pollutants: polychlorinated biphenyls, or PCBs, and polybrominated diphenyl ethers, or PBDEs, both of which may cause a variety of adverse health effects, including neurological, immune and reproductive issues and even cancer (in humans). PCBs were once commonly used in electrical equipment before being banned over health and environmental concerns in the 1970s. The manufacture and import of PBDEs, which are typically used as flame retardants, has also been restricted in the U.S., although at least one common type of the chemical is still permitted.
For the new study, the researchers checked for the presence of these chemicals in two of the world’s deepest ocean trenches — the Mariana trench in the Western Pacific, near the Mariana islands, and the Kermadec trench north of New Zealand. To do so, the researchers deployed special devices called “deep-sea landers,” which are small vessels that are released from ships and drop to the bottom of the ocean before floating back up to the surface.
They found that both PCBs and PBDEs were present in all species of amphipod in both trenches, and at all depths sampled — up to 10,000 metres deep in both locations. . .
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‘No longer pristine’: Not even the world’s deepest ocean trenches are free of pollution, scientists discover
By Chelsea Harvey, Washington Post, February 14, 2017
Banned chemicals from the 70s found in the deepest reaches of the ocean
The University of Aberdeen, February 14, 2017