Aging processes and microplastic release behavior of aquaculture implements

With the rapid development of aquaculture, plastic implements (e.g., buoys, cables, and net curtains) have been widely used. However, long-term environmental exposure has led to their aging and fragmentation, which has become an important source of marine microplastics (MPs) pollution. This study investigated the mechanisms and characteristics of MPs released during the aging process of four types of aquaculture implements. By simulating marine ultraviolet radiation and mechanical abrasion, we conducted indoor aging experiments on polyethylene (PE) net curtains, polypropylene (PP) cables, polyethylene terephthalate (PET) ecological buoys, and polyvinyl chloride (PVC) traditional buoys over a period of 16 weeks, and analyzed the surface morphology, chemical structure, crystallinity change and MPs release. During the aging process, the surfaces of the aquaculture implements became increasingly rough, with the formation of depressions and cracks. Chemical structure analysis revealed a greater increase in oxygen-containing functional groups in PVC and PP compared to PE and PET. Crystallinity measurements showed that all materials exhibited increased crystallinity, with PP cables displaying the most pronounced enhancement, indicating a higher tendency toward embrittlement and fracture. Quantitative analysis of MP release and weight loss ranked the materials as follows: PVC buoys > PP cables > PE nets > PET buoys. This study provides a scientific basis for the optimal selection of aquaculture materials and for strategies to prevent and control microplastic pollution from aquaculture sources.