A sobering reminder that there is no such thing as “away” when you toss out your garbage - for the first time, scientists have measured levels of toxic chemicals from deep ocean ecosystems located at 7,000 to 10,000 meters below sea level. Two sites, the Mariana Trench in the western Pacific Ocean — the world’s deepest trench — and the Kermadec Trench near New Zealand, provided a disturbing picture. Scientists found concentrations of two kinds of persistent organic pollutants (POPs) in small crustaceans called amphipods. The two POPs - polychlorinated biphenyls (PCBs) banned in the 1970’s, were used in electrical equipment as coolants and polybrominated diphenyl ether (PBDEs) flame retardants, many of which have been voluntarily phased out in the last few years.

Researchers note the POPs will continue to accumulate because the chemicals are not flushed out into open waters, as is the case in estuaries or other areas where there is more ocean current movement. Suspected main sources of PCBs in the Mariana Trench are nearby Asian plastic factories and a US military base in Guam. The North Pacific gyre is also located above the trench and could be pushing pollutants deep below the surface. Whatever the source, these findings are cause for concern for a number of reasons, including potentially harming untapped natural resources that could be used for future drug discoveries and potentially compromising the food web and the carbon cycle.

[Source: Nature]