Nanoplastic Generation from Secondary PE Microplastics: Microorganism-Induced Fragmentation

Concern regarding the pollution of the marine environment with plastics has been rising in recent years. Plastic waste residing in and interacting with the environment fragments into secondary particles in the micro- and nanoscale, whose negative impacts on the environment are even greater than those of the parent items. In this work, secondary high density polyethylene (HDPE) and low density polyethylene (LDPE) microplastics were produced by irradiation of virgin films following mechanical fragmentation. The fragments with size ranging from 250 μm to 2 mm were selected for subsequent microcosm experiments. Incubation for 120 days in seawater inoculated with two marine communities, Agios, acclimatized to utilizing plastics as a carbon source, and Souda, as was collected at the Souda bay (Crete, Greece), resulted in biofilm formation by polyethylene (PE) degraders. Monthly FTIR (Fourier-transform infrared spectroscopy) examination of the samples revealed changes in the chemical structure of the surface of the polymers. Dynamic light scattering (DLS) was employed and nano- and microparticles with sizes in the range between 56 nm and 4.5 μm were detected in the seawater of inoculated microcosms. It was thus demonstrated that weathered plastics particles can biodeteriorate and biofragment as a result of biofilm attachment, resulting in the production of nanoplastics due to microbial activity.