Distribution, bioconcentration, trophic transfer and effects of combined exposure of ionic liquid [C₈mim]Br and PMMA...

The expanding manufacturing and utilization of ionic liquids (ILs) and microplastics (MPs) have prompted worldwide environmental health concerns due to their pervasive environmental dispersion. While the toxicological impacts of ILs and MPs on diverse aquatic organisms have been well characterized, their environmental behaviors exhibit considerable complexity owing to the inherent heterogeneity of natural aquatic systems. This study established a simulated freshwater ecosystem containing aqueous phase, benthic sediment, floating plant, submerged plant, shrimp, snail and fish to investigate the environmental behavior and effects of 1-octyl-3-methylimidazolium bromide ([C₈mim]Br) and polymethacrylates (PMMA). Specifically, multicomponent analysis was conducted on their partitioning dynamics, ecotoxicological consequences and trophic transfer mechanisms under chronic exposure. The experimental findings revealed a biphasic adsorption process of [C₈mim]Br, where initial adsorption onto PMMA substrates, ultimately penetrating into PMMA's internal regions. Co-exposure resulted in reduced oxidative stress responses in aquatic biota, whereas benthic organisms demonstrated enlarged oxidative damage due to ingestion of larger particulate aggregates. [C₈mim]Br exhibited trophic level-dependent bioaccumulation patterns across five representative species within the community, though co-exposure with PMMA resulted in attenuated trophic magnification through the food web. Building upon physiological experimental evidence, the integrated biomarker responses (IBR) index was employed to assess the relative toxicities, revealing a comprehensive toxicity hierarchy: PMMA < [C₈mim]Br + PMMA < [C₈mim]Br across biological endpoints.