New insights into the role of marine plastic-gels in microplastic transfer from water to the atmosphere via bubble bursting

• Published in: Water research (Oxford) 2022-08, Vol.222, p.118856-118856, Article 118856
• Main Authors: Shiu, Ruei-Feng, Chen, Lu-Yi, Lee, Hui-Ju, Gong, Gwo-Ching, Lee, Chuping
• Format: Article
• Language: English
• Subjects: Atmospheric plastics; Bubble bursting; Microplastics; Plastic-gels; Surface layer
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2022.118856

•Microplastics can be transferred by bubble bursting at the water–air interface.•First study on plastic-gel enhancement of microplastic transfer from water to air.•High salinity, gel concentration, and viscosity induced microplastic transfer to air.•Plastic-gel formation via cation-linking bridges modulates microplastic transfer capacity. The pervasiveness of microplastics (MPs) in global oceans is raising concerns about their adverse impacts on ecosystems. The mechanistic understanding of MP transport is critical for evaluating its fate, flux, and ecological risks specifically. Currently, bubble bursting is believed to represent an important route for MP transfer from sea surfaces to the atmosphere. However, the detailed mechanisms of the complex physico-chemical interactions between MPs, water composition, and gel particles in the air–sea interface remain unknown. Our results suggested three steps for MP transfer between air–sea phases: (1) MPs incorporating into gel aggregates in the water column; (2) further accumulation of plastic-gel aggregate in the surface layer phase; finally (3) ejection of aggregates from the sea when bubbles of trapped air rise to the surface and burst. The water composition (e.g., high salinity, gel concentration and viscosity) can modulate plastic-gel aggregation and subsequent transport from water to the atmosphere. The possible mechanism may be closely tied to the formation of plastic-gel via cation-linking bridges, thereby enhancing plastic-gel ejection into air. Collectively, this work offers unique insights into the role of marine plastic-gels in determining MP fate and transport, especially at air–sea interfaces. The data also provide a better understanding of the corresponding mechanism that may explain the fates of missing plastics in the ocean. [Display omitted]