Centre for Environmental and Marine Studies (CESAM) & Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
University of Coimbra, Centre for Functional Ecology, Department of Life Sciences, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal.
Sci Total Environ. 2022 Apr 10;816:151642. doi: 10.1016/j.scitotenv.2021.151642. Epub 2021 Nov 23.
Microplastics are ubiquitous contaminants of freshwater ecosystems. However, few ecotoxicity assays have been conducted on freshwater organisms using environmentally relevant concentrations of virgin and weathered microplastics. This work assessed the adverse effects of virgin and artificially weathered fragments of polystyrene and polypropylene on the microalga Raphidocelis subcapitata (72 h growth inhibition assay) and on embryos of the fish Danio rerio (96 h fish embryo assay) under environmentally relevant concentrations (2000-200,000 MP L) and high concentrations (12.5-100 mg L). Sizes of microplastics were measured as tens (polystyrene) to hundreds (polypropylene) of micrometers, while aging was assessed by measuring the carbonyl index. In the microalga, the tested high concentrations promoted growth, while environmentally relevant concentration induced either growth inhibition or promotion. In zebrafish embryos, environmentally relevant concentrations decreased body length and heart rates. No relevant effects were observed in organisms exposed to high concentrations for mortality, malformations, hatching rates, and swimming bladder inflation. Virgin microplastics presented slightly higher toxicity but direct comparison was hindered by the lack of a linear dose-response curve. Despite the lack of a clear pattern, adverse effects were often observed in the lowest environmentally relevant concentrations, raising concerns over the impacts of microplastics on freshwater ecosystems.
微塑料是淡水生态系统中普遍存在的污染物。然而，很少有研究使用环境相关浓度的原始和风化微塑料对淡水生物进行生态毒性测试。本工作评估了原始和人工风化的聚苯乙烯和聚丙烯碎片对微藻斜生栅藻（72 h 生长抑制试验）和斑马鱼胚胎（96 h 鱼胚胎试验）的不良影响，实验使用了环境相关浓度（2000-200,000 MP L）和高浓度（12.5-100 mg L）。微塑料的尺寸测量为数十分微米（聚苯乙烯）到数百微米（聚丙烯），而老化则通过测量羰基指数来评估。在微藻中，测试的高浓度促进了生长，而环境相关浓度则诱导了生长抑制或促进。在斑马鱼胚胎中，环境相关浓度降低了体长和心率。在高浓度暴露下，未观察到死亡率、畸形率、孵化率和鳔充气等相关效应。原始微塑料表现出稍高的毒性，但由于缺乏线性剂量-反应曲线，直接比较受到阻碍。尽管没有明显的模式，但在最低的环境相关浓度下，经常观察到不良影响，这引起了对微塑料对淡水生态系统影响的关注。
