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Polystyrene microplastics facilitate the biotoxicity and biomagnification of ZnO nanoparticles in the food chain from algae to daphnia
Summary
Researchers found that polystyrene microplastics enhanced the toxicity and biological accumulation of zinc oxide nanoparticles in an aquatic food chain from algae to water fleas. When both pollutants were present together, water fleas showed increased oxidative stress, higher heart rates, and greater zinc accumulation compared to exposure to either pollutant alone. The study demonstrates that microplastics can amplify the harmful effects of other nanoparticle contaminants as they move through the food chain.
Ubiquitous microplastics (MPs) may affect the trophic transfer of nanoparticles (NPs), in turn threatening aquatic organisms and even human health. Thus, this study explored the influence of polystyrene microplastics (PS MPs) on the biotoxicity and biomagnification of ZnO nanoparticles (ZnO NPs) in the aquatic food chain from Chlorella vulgaris (C. vulgaris) to Daphnia magna (D. magna). The results showed that PS MPs facilitated the biotoxicity of ZnO NPs towards D. magna after dietary exposure. Compared to the control (single ZnO NPs), the heart rate and the level of reactive oxygen species were remarkably increased by 21.25% and 16.32% in the combined system (PS MPs + ZnO NPs), respectively. Notably, PS MPs suppressed the ZnO NPs accumulation in C. vulgaris, while remarkably facilitating the trophic transfer of ZnO NPs to D. magna. The biomagnification of ZnO NPs was evident with a maximal biomagnification factor (BMF) of 1.49 under acute dietary exposure of PS MPs (72 h), but was absent in the single ZnO NPs system (BMF <0.90). Moreover, PS MPs resulted in a larger biomagnification of ZnO NPs with a maximal BMF of 2.11 under chronic dietary exposure (21 days). Furthermore, the Zn element (including ZnO NPs and released Zn) was observed to accumulate in the intestine, thus causing ultrastructural damage and lipid droplet (LD) aggregate. Overall, these findings highlight the importance of considering the impact of MPs on co-existed pollutants and contribute to a better understanding of the ecological risks of MPs in aquatic ecosystems.