Single and joint toxicity of polymethyl methacrylate microplastics and As (V) on rapeseed (Brassia campestris L.)

Most microplastics and arsenic (As) have been released into farmland via industrial and agricultural activities, posing a potential threat to crop growth and food safety. Thus far, few studies have focused on the phytoxicity of microplastics and As to leafy vegetable. In this study, we evaluated the single and combined toxicological effects of polymethyl methacrylate (PMMA) and As(V) on rapeseed (Brassia campestris L.). Single treatments of two sizes of PMMA particles, namely PMMA nano-plastics (PMMANPs) and PMMA micro-plastics (PMMAMPs) and As(V) significantly (P < 0.05) inhibited the germination index (GI) of rapeseed. The IC50 indicates that PMMANPs were more toxic than PMMAMPs. Combine-pollution experiments demonstrated that the GI, biomass, root length, and sprout length of the rapeseed under the combined treatment were lower than those subjected to As(V) or PMMANPs single treatment. Analysis of variance showed that the interaction effects of PMMANPs and As(V) for GI and root length were significant, and there was synergistic interaction between PMMANPs and As(V) on rapeseed germination. PMMANPs promoted the accumulation of As in sprouts under high As(V) concentrations (40 and 60 mg/L). The activities of lipase in rapeseed generally increased under single and combined treatments of As(V) and PMMANPs, and while alpha-amylase activities first increased and then decreased with the increase of

Automated summary

Microplastics and arsenic released into farmland from industrial and agricultural activities pose a potential threat to crop growth and food safety. This study evaluated the toxic effects of polymethyl methacrylate (PMMA) and arsenic (As) on rapeseed. Results showed that both PMMA nano-plastics (PMMANPs) and PMMA micro-plastics (PMMAMPs) as well as As(V) significantly inhibited rapeseed germination. PMMANPs were more toxic than PMMAMPs. Combined pollution experiments demonstrated that the combined treatment of PMMANPs and As(V) had a greater negative effect on rapeseed germination, biomass, root length, and sprout length compared to single treatments. PMMANPs also promoted the accumulation of As in sprouts under high As(V) concentrations. The activities of lipase and alpha-amylase in rapeseed were affected by the single and combined treatments of As(V) and PMMANPs.