Combined physiological effects of differentially charged nanoplastics and ocean acidification on the mussel Mytilus coruscus

In the context of ocean acidification (OA) in the near future, along with the continuous production of nanoplastics (NPs) with different charges in the ocean, it is critical to investigate their combined effects on marine life and ecosystem stability. Thus, this study assessed the joint effects of NPs with different charges and OA on Mytilus coruscus by analyzing antioxidant stress, energy metabolism, condition index, and shell resistance. Results indicated that positively charged NPs (P-NPs) significantly elevated ROS levels, MDA content, and the activities of GPX and CAT, with more pronounced effects under OA. NPs with different charges have varying effects on energy metabolism enzyme activity, and OA further influences these disparities. Overall, P-NPs had a more detrimental impact on mussels, an effect that was further intensified by OA. Low pH alters the surface charge distribution of NPs, enhancing their binding to biomolecules and potentially exacerbating physiological effects on mussels by altering NPs' aggregation behavior. This study provides insights into the combined toxic effects of NPs with different charges and OA on mussels, offering a reference for evaluating the environmental risks of OA and charged NPs in marine ecosystems.