School of Environmental Science and Engineering, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
School of Environmental Science and Engineering, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
Chemosphere. 2019 Aug;228:195-203. doi: 10.1016/j.chemosphere.2019.04.115. Epub 2019 Apr 17.
Herein we systematically examined the roles of water chemistry (pH, dissolved organic carbon (DOC), and divalent cations) and particle surface functionality that control the aqueous stability, aggregation, and toxicity of engineered nanoplastic particles in simulated natural environmental conditions. Model polystyrene latex nanoparticles (PLNPs) with three different functional groups, namely unmodified (uPLNPs), amine-modified (aPLNPs), and carboxyl-modified (cPLNPs), were investigated. Results indicate that the presence of only DOC increased the surface charge and exhibited negligible effects on the size distribution of the PLNPs in aqueous suspensions. The presence of the divalent cations (Ca and Mg) was observed to decrease the surface charge and increase the size of the PLNPs. The coexistence of DOC and the divalent cations enhanced the extent of aggregation of the PLNPs in the water columns. The surface modification and pH were sensitive factors influencing the stability of PLNPs during long-term suspension when DOC and the divalent cations coexisted. Direct visual further testified the conclusions on the combined effects of solution and surface chemistry parameters. Furthermore, in situ transmission electron microscope observations revealed that the enhancement of PLNP aggregation in the presence of DOC and the divalent cation was caused by bridge formation. Toxicity test indicated the PLNPs exhibited acute toxicity and physical damage to Daphnia magna. The more complex the solution conditions, the more toxicity the aPLNPs and cPLNPs. Analysis of mode of toxic action implied that the PLNPs mainly caused the accumulation of oxidative damage to the gut of D. magna.
在此，我们系统地研究了水化学（pH 值、溶解有机碳（DOC）和二价阳离子）和颗粒表面功能，这些因素控制着工程纳米塑料颗粒在模拟自然环境条件下的水相稳定性、聚集和毒性。研究了具有三种不同官能团的模型聚苯乙烯乳胶纳米颗粒（PLNPs），即未改性（uPLNPs）、胺改性（aPLNPs）和羧基改性（cPLNPs）。结果表明，仅存在 DOC 会增加颗粒表面电荷，但对 PLNPs 在水悬浮液中的粒径分布几乎没有影响。存在二价阳离子（Ca 和 Mg）时，会降低颗粒表面电荷并增加 PLNPs 的粒径。DOC 和二价阳离子的共存会增强 PLNPs 在水柱中的聚集程度。表面改性和 pH 值是在 DOC 和二价阳离子共存时影响 PLNPs 长期悬浮稳定性的敏感因素。直接目视观察进一步证明了溶液和表面化学参数共同作用的结论。此外，原位透射电子显微镜观察表明，DOC 和二价阳离子的存在增强了 PLNP 的聚集，这是由于桥接形成所致。毒性测试表明，PLNPs 对大型溞（Daphnia magna）表现出急性毒性和物理损伤。溶液条件越复杂，aPLNPs 和 cPLNPs 的毒性就越大。毒性作用模式分析表明，PLNPs 主要导致大型溞肠道积累氧化损伤。
