Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China; The National Field Station of Freshwater Ecosystem of Liangzi Lake, Department of Ecology, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
Environ Pollut. 2021 Jun 15;279:116900. doi: 10.1016/j.envpol.2021.116900. Epub 2021 Mar 13.
Glyphosate and microplastics are widely found in marine, terrestrial, and freshwater environments due to their globally widespread application. Further, they have proved to have specific ecotoxicity effects on aquatic plants. However, few studies have focused on the effects of small plastic particles and glyphosate, or especially, their combined effect on vascular plants in freshwater ecosystems. This study aimed to conduct a simulated greenhouse experiment to investigate the ecotoxicity of polystyrene microplastics and glyphosate on the floating plant Salvinia cucullata by exposure to fluorescent polystyrene microplastics (1 μm; concentration, 3, 15, and 75 mg/L), glyphosate (5, 25, and 50 mg/L), and a mixture of the two (3 + 5, 15 + 25, and 75 + 50 mg/L) for seven days. Glyphosate significantly reduced the relative growth rate, photosynthetic capacity, and root activity of S. cucullata. Polystyrene microplastics did not significantly influence photosynthesis or leaf morphological characteristics but they significantly reduced relative growth rate and root activity in S. cucullata, indicating that the effects of microplastics on aquatic plants are potentially associated with different organs exposed to pollution. Polystyrene microplastics and glyphosate activated the plant antioxidant defense systems by increasing antioxidative enzyme activities including, superoxide dismutase, ascorbate peroxidase, and catalase to cope with oxidative stress. Synergistic effects (only observed in percent leaf yellowing) were observed when S. cucullata was exposed to a high concentrations (≥15 + 25 mg/L) of glyphosate and microplastics. Our results indicate that pervasive microplastics and herbicide contamination in freshwater may potentially affect the growth of aquatic plants.
草甘膦和微塑料由于其在全球范围内的广泛应用，广泛存在于海洋、陆地和淡水环境中。此外，它们已被证明对水生植物具有特定的生态毒性作用。然而，很少有研究关注小塑料颗粒和草甘膦的影响，特别是它们在淡水生态系统中对维管束植物的联合影响。本研究旨在进行模拟温室实验，通过暴露于荧光聚苯乙烯微塑料（1μm；浓度为 3、15 和 75mg/L）、草甘膦（5、25 和 50mg/L）和两者的混合物（3+5、15+25 和 75+50mg/L）来研究聚苯乙烯微塑料和草甘膦对浮萍的生态毒性，共暴露 7 天。草甘膦显著降低了浮萍的相对生长率、光合能力和根活力。聚苯乙烯微塑料对光合作用或叶片形态特征没有显著影响，但显著降低了浮萍的相对生长率和根活力，这表明微塑料对水生植物的影响可能与暴露于污染的不同器官有关。聚苯乙烯微塑料和草甘膦通过增加超氧化物歧化酶、抗坏血酸过氧化物酶和过氧化氢酶等抗氧化酶的活性，激活了植物的抗氧化防御系统，以应对氧化应激。当浮萍暴露于高浓度（≥15+25mg/L）的草甘膦和微塑料时，观察到协同作用（仅在叶片发黄百分比中观察到）。我们的结果表明，淡水环境中普遍存在的微塑料和除草剂污染可能会对水生植物的生长产生潜在影响。
