Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China.
Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China; School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Chemosphere. 2018 Oct;208:59-68. doi: 10.1016/j.chemosphere.2018.05.170. Epub 2018 May 29.
Microplastics are widely identified in aquatic environments, but their impacts on phytoplankton have not been extensively studied. Here, the responses of Chlorella pyrenoidosa under polystyrene (PS) microplastics exposure were studied across its whole growth period, with microplastic sizes of 0.1 and 1.0 μm and 3 concentration gradients each, which covered (10 and 50 mg/L) and exceeded (100 mg/L) its environmental concentrations, respectively. PS microplastics caused dose-dependent adverse effects on Chlorella pyrenoidosa growth from the lag to the earlier logarithmic phases, but exhibited slight difference in the maximal inhibition ratio (approximately 38%) with respect to the two microplastic sizes. In addition to the reduced photosynthetic activity of Chlorella pyrenoidosa, unclear pyrenoids, distorted thylakoids and damaged cell membrane were observed, attributing to the physical damage and oxidative stress caused by microplastics. However, from the end of the logarithmic to the stationary phase, Chlorella pyrenoidosa could reduce the adverse effects of microplastics jointly through cell wall thickening, algae homo-aggregation and algae-microplastics hetero-aggregation, hence triggering an increase of algal photosynthetic activity and its growth, and cell structures turned to normal. Our study confirmed that PS microplastics can impair but then enhance algae growth, which will be helpful in understanding the ecological risks of microplastics.
微塑料广泛存在于水生环境中，但它们对浮游植物的影响尚未得到广泛研究。在这里，我们研究了聚对苯二甲酸乙二酯（PS）微塑料在整个生长周期内对蛋白核小球藻的影响，微塑料的粒径分别为 0.1μm 和 1.0μm，每个粒径有 3 个浓度梯度，分别覆盖（10 和 50mg/L）和超过（100mg/L）其环境浓度。PS 微塑料对蛋白核小球藻的生长表现出剂量依赖性的不良影响，从迟滞期到早期对数期，但对两种微塑料粒径的最大抑制率（约 38%）表现出轻微差异。除了降低蛋白核小球藻的光合作用活性外，还观察到了不清楚的蛋白核、扭曲的类囊体和受损的细胞膜，这归因于微塑料造成的物理损伤和氧化应激。然而，从对数期到静止期，蛋白核小球藻可以通过细胞壁增厚、藻类同聚和藻类-微塑料异聚来共同减轻微塑料的不利影响，从而引发藻类光合作用活性和生长的增加，细胞结构恢复正常。我们的研究证实，PS 微塑料可以损害但随后增强藻类的生长，这将有助于理解微塑料的生态风险。
