Banned chemicals persist in deep ocean

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Banned chemicals persist in deep ocean

 

The amphipods were retrieved from the Pacific's Kermadec and Mariana trenches

 

Chemicals banned in the 1970s have been found in the deepest reaches of the Pacific Ocean, a new study shows.

Scientists were surprised by the relatively high concentrations of pollutants like PCBs and PBDEs in deep sea ecosystems.

 

Used widely during much of the 20th Century, these chemicals were later found to be toxic and to build up in the environment.

 

The results are published in the journal Nature Ecology and Evolution.

The team led by Dr Alan Jamieson at the University of Newcastle sampled levels of pollutants in the fatty tissue of amphipods (a type of crustacean) from deep below the Pacific Ocean surface.

 

The animals were retrieved using specially designed "lander" vehicles deployed from a boat over the Mariana and Kermadec trenches, which are over 10km deep and separated from each other by 7,000km.

 

Not broken down

The pollutants found in the amphipods included polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), which were commonly used as electrical insulators and flame retardants.

 

PCB production was banned by the US in 1979 and by the Stockholm Convention on Persistent Organic Pollutants, a UN treaty signed in 2001.

 

From the 1930s to when PCBs were banned in the 1970s, the total global production of these chemicals is estimated to be in the region of 1.3 million tonnes.

 

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