With the increasing use of silver nanoparticles (Ag-NPs), their entrance into aquatic ecosystems is inevitable. Thus, the present study simulated the potential fate, toxicity, and bioaccumulation of Ag-NPs released into aquatic systems with different salinities. The Ag-NPs were characterized using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), and UV-vis spectroscopy. Juvenile rainbow trout were exposed to Ag-NPs in three different salinity concentrations, including low (0.4 ppt), moderate (6 ± 0.3 ppt), and high (12 ± 0.2 ppt) salinity, for 14 days in static renewal systems. The nominal Ag-NP concentrations in the low salinity were 0.032, 0.1, 0.32, and 1 ppm, while the Ag-NP concentrations in the moderate and high salinity were 3.2, 10, 32, and 100 ppm. UV-vis spectroscopy was used during 48 h (re-dosing time) to evaluate the stability and possible changes in size of the Ag-NPs in the water. The results revealed that the λmax of the Ag-NPs remained stable (415-420 nm) at all concentrations in the low salinity with a reduction of absorbance between 380 and 550 nm. In contrast, the λmax quickly shifted to a longer wavelength and reduced absorbance in the moderate and higher salinity. The bioaccumulation of Ag in the studied tissues was concentration-dependent in all the salinities based on the following order: liver>kidneys≈gills>white muscles. All the tissue silver levels were significantly higher in the high salinity than in the moderate salinity. In addition, all the fish exposed to Ag-NPs in the low, moderate, and high salinity showed a concentration-dependent increase in their hepatosomatic index (HSI). In conclusion, most Ag-NPs that enter into freshwater ecosystems (low ionic strength) remain suspended, representing a potentially negative threat to the biota in an ionic or nanoscale form. However, in a higher salinity, nanoparticles agglomerate and precipitate on the surface of the sediment.

译文

随着银纳米颗粒(Ag-NPs)的日益使用,它们不可避免地进入水生生态系统。因此,本研究模拟了被释放到具有不同盐度的水生系统中的Ag-NPs的潜在命运,毒性和生物蓄积性。使用电感耦合等离子体原子发射光谱(ICP-AES),动态光散射(DLS),透射电子显微镜(TEM),能量色散X射线分析(EDX)和紫外可见光谱对Ag-NP进行表征。在静态更新系统中,将幼虹鳟暴露于三种不同盐度浓度的Ag-NP中,包括低盐度(0.4 ppt),中度盐度(6±0.3 ppt)和高盐度(12±0.2 ppt),持续14天。低盐度的标称Ag-NP浓度为0.032、0.1、0.32和1 ppm,而中盐度和高盐度的Ag-NP浓度为3.2、10、32和100 ppm。在48小时(重新加药时间)中使用了紫外可见光谱法来评估水中Ag-NP的稳定性和大小可能发生的变化。结果表明,在低盐度下,所有浓度的Ag-NPs的λmax都保持稳定(415-420 nm),并且在380 nm至550 nm之间的吸光度降低。相反,在中度和较高盐度下,λmax迅速移至更长的波长并降低了吸光度。在所有盐度中,Ag在生物组织中的生物累积量均取决于浓度,其顺序为:肝脏>肾脏≈g>白肌肉。高盐度下的所有组织银含量均显着高于中盐度。此外,所有在低盐度,中度盐度和高盐度条件下暴露于Ag-NPs的鱼的肝体指数(HSI)均呈浓度依赖性增加。总之,大多数进入淡水生态系统(低离子强度)的Ag-NP都保持悬浮状态,以离子或纳米级形式对生物群构成潜在的负面威胁。然而,在更高的盐度下,纳米颗粒附聚并沉淀在沉积物的表面上。

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