Abstract: In order to investigate the effects of plastics on plant growth, this paper synthesized polystyrene(PS) nanoplastics with different surface charges by microemulsion polymerization: positively charged $ NH_{2} $-polystyrene( $ NH_{2} $-PS) and negatively charged $ SO_{3} $H-polystyrene( $ SO_{3} $H-PS). Different mass concentration gradients (50, 100, 200 $ \mu $g/mL) were used to simulate PS residues in the environment, and the effects of PS on tobacco growth were evaluated by plant phenotype, chlorophyll amount, chlorophyll fluorescence-related parameters, reactive oxygen species, lipid peroxides accumulation and antioxidant-related enzyme activities. The results showed that tobacco exposed to different charges of PS exhibited reduced plant size and leaf yellowing compared with the control group, and the inhibitory effect of $ SO_{3} $H-PS was stronger than that of $ NH_{2} $-PS. The results of chlorophyll amount and chlorophyll fluorescence parameters indicated that both PS nanoplastics inhibited leaf chlorophyll synthesis and photosynthesis to varying degrees, resulting in yellowing of the leaves of the plants. The measurements of leaf hydrogen peroxide, malondialdehyde(MDA) accumulation and antioxidant-related enzyme activities showed that both PS nanoplastics caused the accumulation of $ H_{2}O_{2} $ and MDA, activated the antioxidant enzyme activities of tobacco, and led to the increase of SOD, POD, and CAT enzyme activities. The results of the study can be useful for investigating the effects of common PS nanoplastics in the atmosphere on plant growth.
Keywords: nanoplastics; charge; tobacco; photosynthesis; antioxidant enzyme activity
合肥工业大学学报自科版