Scientists were “surprised” at the high levels in concentration of old-timey pollutants like PCBs and PBDEs in deep ocean ecosystems. “Surprised” because these are chemicals outlawed over 40 years ago now.
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.
The issue here is that these chemicals haven’t broken down as much as people had hoped. In fact, they seem to have sunk to the bottoms of our oceans.
But they add that in the Mariana trench, the highest levels of PCBs were 50 times greater than in crabs from paddy fields fed by the Liaohe River, one of the most polluted rivers in China.
Dr Jamieson commented: "The amphipods we sampled contained levels of contamination similar to that found in Suruga Bay [in Japan], one of the most polluted industrial zones of the northwest Pacific."
At the very least, this shows how connected the deepest reaches of our oceans are to what we can all see and touch. While the long term ramifications are unknown, some more research is clearly warranted.