Effects of polypropylene and polyethylene microplastics on growth and photosynthetic pigment synthesis by Scenedesmus sp.

This study examines the impact of polyethylene and polypropylene microplastics on the growth and pigment production of Scenedesmus sp. at three different concentrations (50, 100, and 150 mg L-1). The findings demonstrate that microplastic exposure negatively impacts microalgae growth and photosynthetic pigments, irrespective of polymer type, size, and concentration. The findings indicate that the reduction in total chlorophyll percentage and the suppression of microalgal development were more pronounced for particles smaller than 500 μm and at a concentration of 150 mg L-1. The percentage reduction in carotenoid levels remained consistent at 50 and 100 mg L-1 but decreased considerably at 150 mg L-1. In addition, phthalate release from the microplastics was studied for a mixture of polypropylene and polyethylene microplastics. Several phthalates were detected in the samples namely diethyl phthalate (4.43 ng mL-1), dibutyl phthalate (389.38 ng mL-1), benzyl butyl phthalate (0.81 ng mL-1), and diisobutyl phthalate (3.92 ng mL-1), each of which presents ecological hazards. We recommend further studies to investigate the long-term environmental impacts of these interactions.