College of Landscape Architecture and Forestry, Qingdao Agricultural University, Qingdao 266100, China.
College of Life Sciences, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Normal University, Shi jiazhuang 050024, China.
Sci Total Environ. 2023 Sep 20;892:164518. doi: 10.1016/j.scitotenv.2023.164518. Epub 2023 May 30.
Nanoplastics, as emerging contaminants are being released into aquatic environments with their increasing applications, and induce potential hazards to aquatic ecosystem. In this work, we investigated the removal process of polystyrene nanoparticles (PS NPs) by Eichhornia crassipes and the related photosynthetic responses of E. crassipes. Results showed that both sizes of PS NPs (20 and 200 nm) with 50 mg/L induced the prominent damage on the root epidermis after 48 h exposure, and smaller size PS NPs caused the greater damage. PS NPs has been entered the roots of E. crassipes and migrated from the epidermis, cortex, to vascular system by using confocal laser scanning microscopy observation. Scanning electron microscope images confirmed the distribution of PS NPs (200 nm) in the roots. The crack at sites of primary-lateral root junction was an important way for the uptake of PS NPs, which destroyed the defense of Casparian strip, and promoted the migration of PS NPs into the vascular system. PS NPs entered the submerged leaves by stomata and the intercellular spaces of lower epidermis. Moreover, PS NPs in the plants showed significant inhibition on net photosynthetic rate, intercellular CO concentration, stomatal conductance, and transpiration rate. This study concluded the absorption and migration processes of PS NPs by E. crassipes, and the negative effects on photosynthesis, which will be useful for guiding the floating plants application for PS NPs removal in aqueous environment and ecological improvement.
纳米塑料作为新兴污染物，随着其应用的增加而被释放到水生环境中，对水生生态系统可能造成潜在危害。在这项工作中，我们研究了凤眼莲对聚苯乙烯纳米颗粒（PS NPs）的去除过程及其相关的光合作用响应。结果表明，两种尺寸的 PS NPs（20 和 200nm）浓度为 50mg/L 暴露 48 小时后，均对根表皮造成明显损伤，且小尺寸 PS NPs 造成的损伤更大。通过共聚焦激光扫描显微镜观察，PS NPs 已进入凤眼莲的根部，并从表皮、皮层迁移到维管束系统。扫描电子显微镜图像证实了 PS NPs（200nm）在根部的分布。初生侧根交界处的裂缝是 PS NPs 摄取的重要途径，它破坏了凯氏带的防御功能，促进了 PS NPs 向维管束系统的迁移。PS NPs 通过气孔和下表皮的细胞间隙进入沉水叶片。此外，植物中的 PS NPs 对净光合速率、胞间 CO 浓度、气孔导度和蒸腾速率有明显的抑制作用。本研究总结了 PS NPs 被凤眼莲吸收和迁移的过程，以及对光合作用的负面影响，这将有助于指导浮叶植物在水环境保护和生态改善方面对 PS NPs 的去除应用。
