Early signs of plastic degradation and fragmentation: A 40-day study in marine environments

Conventional plastics are widely present in the ocean as marine plastic debris. This in-situ study investigates the degradability and fragmentation of seven common conventional plastics (PET, PVC, PS, EPS, PP, HDPE, and LDPE) in natural marine environments over a 40-day period. All plastics showed significant chemical changes and oscillating plastic oxidation levels, indicating the synergistic processes of oxidation and removal of oxidation products. Polystyrenes and polymers with heteroatoms showed the largest degradation potentials, while pure polyolefins exhibited the highest fragmentation risks. SEM images suggest potentials of EPS and pure polyolefins in generating microplastic fragments, and polymers with heteroatoms in generating nanoplastic fragments. PS did not exhibit any surface degradation signs, potentially due to enhanced crystallinity through oxidation. The findings highlight the need for reduced usage of EPS and pure polyolefins which are commonly applied as disposable utensils and food packaging, and prioritized cleanup of these polymers to reduce microplastic pollution in the environment.