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Toxicity effects of microplastics and lead(II) ion co-exposure on Chlorella: Protein- and enzyme-level responses
Summary
Researchers examined the combined toxic effects of polyethylene and polypropylene microplastics with lead ions on the freshwater alga Chlorella, focusing on protein and enzyme-level responses. They found that co-exposure altered protein expression and enzymatic activity in ways that differed from single-pollutant exposure. The study highlights that microplastics and heavy metals can interact to produce complex biomolecular responses in aquatic organisms.
Microplastics (MPs) synergistically interact with heavy metal contaminants, posing substantial ecological threats to biota. Hydrodynamic regimes and water-level fluctuations within the Three Gorges Reservoir (TGR) critically influence contaminant dynamics. Nevertheless, biomolecular responses to MP and heavy metal co-exposure at protein and enzymatic levels remain inadequately characterized. This study selected polyethylene (PE), polypropylene (PP), and lead(II) ions (Pb2+) to examine the freshwater microalgae Chlorella vulgaris within the TGR. After 96 h of exposure, the half-maximal effective concentrations for PE and PP against C. vulgaris were determined to be 334 mg/L and 295.29 mg/L, respectively. PE, PP, and Pb2+ significantly reduced the accumulation of C. vulgaris biomass, deteriorated algal cell growth, and caused the algal cells to undergo membrane lipid peroxidation. Nitrate and phosphate assimilation were considerably inhibited across all treatments, with heightened suppression under co-exposure. MPs’ addition significantly increased malondialdehyde levels. MP adsorption of Pb2+ appeared to attenuate Pb2+-associated changes in nitrate reductase (NR) and alkaline phosphatase activities. This study provides a theoretical foundation for evaluating MP and heavy metal ecological risks in reservoir ecosystems.