Toxicological effects of microplastics and sulfadiazine on Artemia sinica

Sulfadiazine (SDZ) is a widely used antibiotic that raises significant environmental concerns. Despite the role of microplastics (MPs) in facilitating the adsorption of environmental organic pollutants and influencing their toxicity to organisms, further research is necessary to understand the combined and individual effects of PS and SDZ on Artemia sinica. This study conducted experiments with varying concentrations of SDZ (0.16 mg/L, 0.8 mg/L, 4 mg/L, and 20 mg/L) both individual and combination treatments with 4 mg/L of PS to elucidate the potential toxic mechanisms. The results showed that three treatments significantly reduced swimming speed and altered antioxidant capacity, as evidenced by changes in superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. Notably, combined exposure resulted in a reduction of swimming speed by 33 %-42 % compared to individual treatment with SDZ. Additionally, antioxidant responses were found to be 1.78 to 4.2 times greater than those observed with SDZ alone., The combined stress led to more severe intestinal villi damage and cell vacuolation, decreased clearance capability, and increased cell apoptosis, along with a rise in total antioxidant capacity. The contents and enzyme activity related to energy metabolism also decreased with increasing concentrations of the combined treatment. Energy metabolism markers, including α-amylase activity, exhibited reductions ranging from 21 % to 77 % compared to individual treatments as the combined concentrations increased. Furthermore, the combined exposure disrupted the intestinal microbiota, leading to a reduction in both diversity and abundance. These findings indicate that PS and SDZ exert dose-dependent and synergistic toxic effects on A. sinica, thereby enhancing our understanding of their combined toxicity and supporting ecological risk assessments.