Eroded plastic pellets as monitoring tools for polycyclic aromatic hydrocarbons (PAH): laboratory and field studies

Through transportation accidents or intentional releases, plastic pellets (small granules 1-5 mm in
diameter) are widely distributed in the ocean all over the world. These pellets accumulate organic
pollutants and can be used for the determination of diffusive seawater pollution. Pellets
demonstrating a certain degree of erosion are expected to have enough contact time with the water
pollutants and thus, reach sorption equilibrium with the water phase. In the present study, eroded
pellets collected from Greek beaches, were separated into polyethylene (PE) and polypropylene
(PP). Polycyclic aromatic hydrocarbons (PAHs, i.e. naphthalene, phenanthrene, and pyrene) were
used as model compounds to study the uptake kinetics into these eroded pellets. Naphthalene
uptake demonstrates similar kinetics in both eroded PE and PP. Phenanthrene and pyrene uptake
demonstrates slower kinetic rates by eroded PE than by virgin PE and similar kinetic rates by eroded
and virgin PP. These observations are then used to evaluate PAHs measurements in pellets
sampled from two sampling sites in Saronikos Gulf. It is concluded that seawater in Loutropyrgos
beach is polluted by PAHs more than seawater in Aegena island. PAH pollution in both sampling
sites is of pyrogenic origin.