The fragments of plastic waste floating on the surface of the oceans are symptomatic of wider pollution affecting the marine environment as a whole. To assess this pollution and understand the global fate of plastic in the oceans, scientists are studying the mechanisms by which plastic is distributed and degraded in water. To date, however, they still have insufficient knowledge, particularly of the deep ocean environment.
A research team has been looking into the issue of the release of additives contained in plastics into water. This work was carried out as part of the JPI-Ocean PLASTOX programme (ANR PLASTOX). Most of the additives that have been detected in coastal and open sea environments are endocrine disruptors that could have harmful consequences for marine biodiversity and, by extension, human health. This study compares the leaching into seawater of organic additives from standardised plastic materials selected by an assembly of natural prokaryotes in surface conditions and in high-pressure conditions encountered in the deep sea.
This research shows that the release of additives is greater at the ocean surface than in deep waters. The increase in hydrostatic pressure inhibits the release of the heaviest organic additives, such as tris(2-ethylhexyl) phosphate and diisononyl phthalate, which are found in polyethylene and polyvinyl chloride. Moreover, most of the plastic fragments that sink along the water column are degraded long before they reach the sedimentary layer of the deep environment. Nevertheless, prokaryotes living in deep waters, like those in surface waters, favour the release of additives (phthalates, bisphenols, organophosphate esters).
More information
Organic additive release from plastic to seawater is lower under deep-sea conditions - Nature Communications (2021)
Vincent Fauvelle, Marc Garel, Christian Tamburini, David Nerini, Javier Castro-Jiménez, Natascha Schmidt, Andrea Paluselli, Armand Fahs, Laure Papillon, Andy M. Booth and Richard Sempéré