Per- and Polyfluoroalkyl Substances Leaching from Micro- and Nanoplastics and the Associated Influence of the Plastisphere

Micro- and nanoplastics (MNPs) act as vectors for persistent
organic
pollutants in marine environments, yet their role in leaching of per-
and polyfluoroalkyl substances (PFAS) remains poorly understood. We
investigated PFAS leaching from MNPs during a 3-month seawater incubation
experiment and explored the potential influence of the plastisphere
on PFAS release dynamics. We quantified unknown PFAS using the total
oxidizable precursor assay (TOPA) by converting oxidizable precursors
into detectable perfluoroalkyl acids. Targeted chemical analysis quantified
PFAS in MNPs and seawater leachates. While multiple PFAS were successfully
solvent extracted (sequential extractions using acetonitrile:isopropanol
and hexane) from various MNPs, detectable leaching into seawater occurred
exclusively from polytetrafluoroethylene and fluorinated ethylene
propylene MNPs. TOPA revealed the highest total PFAS concentrations
in fluoropolymer MNPs, indicating the presence of oxidizable precursors
and suggesting additional PFAS formation potential beyond the extractable
fraction. A plastisphere-isolated bacterium significantly influenced
the leaching of short-chain perfluoroalkyl carboxylic acids, specifically
perfluoropentanoic acid, perfluorohexanoic acid, and perfluoroheptanoic
acid, with the total PFAS concentration leached higher without than
with bacteria. This finding suggests that marine microbial activity
within the plastisphere may actively modulate the fate of MNP-bound
PFAS, potentially altering their bioavailability and ecological impact.