School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
Aquat Toxicol. 2019 Apr;209:113-120. doi: 10.1016/j.aquatox.2019.02.003. Epub 2019 Feb 5.
Thorium (Th) is a natural radioactive element present in the environment and has the potential to be used as a clean nuclear fuel. Relatively little is known about the aquatic toxicity of Th, especially in nanoparticulate form, which may be the main chemical species of Th in the natural waters. In this study, impacts of ThO nanoparticles (NPs) with two different sizes (52 ± 5 nm, s-ThOvs. 141 ± 6 nm, b-ThO) on a green alga Chlorella pyrenoidosa (C. pyrenoidosa) were evaluated. Results indicated that C. pyrenoidosa was more sensitive to s-ThO (96-h EC = 64.1 μM) than b-ThO (96-h EC = 100.2 μM). Exposure to 200 μM of ThO NPs reduced the chlorophyll-a and chlorophyll-b contents of the algal cells. At 96 h, SEM and TEM showed that more agglomerates of s-ThO than those of b-ThO were attached onto the surface of algal cells. Reactive oxygen species (ROS) generation and membrane damage were induced after the attachment of high concentrations of ThO NPs. The heteroagglomeration between ThO NPs and algal cells and increased oxidative stress might play important roles in the toxicity of ThO NPs. To the best of our knowledge, this is the first report on aquatic toxicity of ThO NPs.
钍（Th）是一种存在于环境中的天然放射性元素，具有作为清洁核燃料的潜力。关于 Th 的水生毒性，特别是在纳米颗粒形式下的毒性，相对知之甚少，而在天然水中，Th 可能主要以纳米颗粒的形式存在。在这项研究中，评估了两种不同尺寸（52±5nm，s-ThOvs. 141±6nm，b-ThO）的 ThO 纳米颗粒（NPs）对绿藻栅藻（C. pyrenoidosa）的影响。结果表明，s-ThO（96-h EC=64.1μM）对 C. pyrenoidosa 的敏感性高于 b-ThO（96-h EC=100.2μM）。暴露于 200μM 的 ThO NPs 会降低藻类细胞的叶绿素-a 和叶绿素-b 含量。在 96 小时时，SEM 和 TEM 显示，s-ThO 的团聚体比 b-ThO 的团聚体更多地附着在藻类细胞的表面。在高浓度 ThO NPs 附着后，会产生活性氧物种（ROS）并导致细胞膜损伤。ThO NPs 与藻类细胞的异团聚和氧化应激增加可能在 ThO NPs 的毒性中起重要作用。据我们所知，这是第一篇关于 ThO NPs 水生毒性的报告。
