Valdosta State University , 1500 North Patterson Street, Valdosta, Georgia 31698, United States.
Environ Sci Technol. 2014 Nov 18;48(22):13443-50. doi: 10.1021/es501187g. Epub 2014 Nov 5.
Discharges of metal oxide nanoparticles into aquatic environments are increasing with their use in society, thereby increasing exposure risk for aquatic organisms. Separating the impacts of nanoparticle from dissolved metal pollution is critical for assessing the environmental risks of the rapidly growing nanomaterial industry, especially in terms of ecosystem effects. Metal oxides negatively affect several species of marine phytoplankton, which are responsible for most marine primary production. Whether such toxicity is generally due to nanoparticles or exposure to dissolved metals liberated from particles is uncertain. The type and severity of toxicity depends in part on whether phytoplankton cells take up and accumulate primarily nanoparticles or dissolved metal ions. We compared the responses of the marine diatom, Thalassiosira weissflogii, exposed to ZnO, AgO, and CuO nanoparticles with the responses of T. weissflogii cells exposed to the dissolved metals ZnCl2, AgNO3, and CuCl2 for 7 d. Cellular metal accumulation, metal distribution, and algal population growth were measured to elucidate differences in exposure to the different forms of metal. Concentration-dependent metal accumulation and reduced population growth were observed in T. weissflogii exposed to nanometal oxides, as well as dissolved metals. Significant effects on population growth were observed at the lowest concentrations tested for all metals, with similar toxicity for both dissolved and nanoparticulate metals. Cellular metal distribution, however, markedly differed between T. weissflogii exposed to nanometal oxides versus those exposed to dissolved metals. Metal concentrations were highest in the algal cell wall when cells were exposed to metal oxide nanoparticles, whereas algae exposed to dissolved metals had higher proportions of metal in the organelle and endoplasmic reticulum fractions. These results have implications for marine plankton communities as well as higher trophic levels, since metal may be transferred from phytoplankton through food webs vis à vis grazing by zooplankton or other pathways.
金属氧化物纳米颗粒排放到水生环境中，随着其在社会中的使用而增加，从而增加了水生生物的暴露风险。将纳米颗粒的影响与溶解金属污染区分开来，对于评估快速发展的纳米材料行业的环境风险至关重要，特别是在生态系统效应方面。金属氧化物对多种海洋浮游植物产生负面影响，而浮游植物是海洋初级生产力的主要来源。这种毒性是否通常归因于纳米颗粒或暴露于从颗粒中释放的溶解金属尚不确定。毒性的类型和严重程度部分取决于浮游植物细胞主要吸收和积累的是纳米颗粒还是溶解的金属离子。我们比较了海洋硅藻新月菱形藻暴露于 ZnO、AgO 和 CuO 纳米颗粒与新月菱形藻细胞暴露于 ZnCl2、AgNO3 和 CuCl2 溶解金属 7 天的反应。测量细胞金属积累、金属分布和藻类种群增长，以阐明不同形式金属暴露的差异。在暴露于纳米金属氧化物和溶解金属的新月菱形藻中观察到浓度依赖性金属积累和种群生长减少。在所有测试的金属中，最低浓度下对种群生长的影响显著，溶解金属和纳米颗粒金属的毒性相似。然而，暴露于纳米金属氧化物的新月菱形藻细胞的金属分布与暴露于溶解金属的新月菱形藻细胞的金属分布明显不同。当细胞暴露于金属氧化物纳米颗粒时，金属浓度在藻类细胞壁中最高，而暴露于溶解金属的藻类细胞器和内质网部分的金属比例更高。这些结果对海洋浮游植物群落以及更高营养级生物都有影响，因为金属可能通过浮游植物通过浮游动物或其他途径摄食的食物网进行转移。
