Impact of Nano-Polystyrene on Growth Rate and Physiological Metabolism of Microalgae Chlorella vulgaris

The world considers nano-plastic pollution to be one of the major emerging health threats due to human beings' poor consumption and recycling practices of the increasing waste products. To find out how microplastics affect primary productivity in the environment, we tested how harmful polystyrene microplastics (PS-MPs) are to the microalgae Chlorella vulgaris (C. vulgaris). In particular, the growth rate and antioxidant enzyme activity of the microalgae in the presence of different PS-MP concentrations (0, 30 μg/l, 60 μg/l, 120 μg/l, 0.5 mg/l, 5 mg/l, and 10 mg/l) were monitored under three spectra (red, blue, and white). These new data revealed a decrease in microalgae growth rates at the 10th day of exposure in the red spectrum in response to different-dose PS-MP exposure. In contrast, a blue spectrum shows an early increase in microalgae growth rate in response to low-dose PS-MP exposure. In contrast, a higher concentration of PS-MP solution leads to significant inhibition within 15th days. Meanwhile, the superoxide dismutase (SOD) level increases in the red and blue spectra and decreases in the white spectra. All spectra show an increase in CAT levels. Overall, our study comprehensively explores the toxicity of microplastics on microalgae, providing a thorough understanding of the potential effects of plastic pollution on the entire food web in the aquatic environment. We observed a reduction in C. vulgaris antioxidant enzyme activity in the red and blue spectrum after exposure, along with an increase in antioxidant activities.