Impact of microplastic types and aging degrees on the transport behavior of marine oil spills

Marine oil spills and microplastics (MPs) pollution pose dual threats to the current marine environment. However, researchers have paid limited attention to how different types of MPs affect the transport behavior of oil spills. This study evaluated the impact of four common MPs with varying degrees of UV aging on oil spill behavior, focusing on their roles in the formation of MPs-oil agglomerates (MOA), oil dispersion and sedimentation. MPs and oil primarily undergo agglomeration through interactions between hydrophobic and van der Waals forces. UV aging reduced the degree of agglomeration between MPs and oil. The aged MPs had more oxygen-containing functional groups and more negative potential. These properties enhanced electrostatic repulsion while decreasing hydrophobic and van der Waals interactions. Aged MPs promoted oil dispersion, and the oil dispersion efficiency increased by 6.6-13.7 % while inhibiting oil sedimentation. The types and aging degrees of MPs were found to significantly affect their interaction with the oil, which further affected the transport behavior of oil spills in the water column. These findings could facilitate scientific evaluation of the role of MPs in the oil spill migration process and the potential threat of complex pollutants to the marine ecosystem.