Wu Fan, Bortvedt Amy, Harper Bryan J, Crandon Lauren E, Harper Stacey L
School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, United States.
Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, United States.
Aquat Toxicol. 2017 Sep;190:78-86. doi: 10.1016/j.aquatox.2017.06.021. Epub 2017 Jun 26.
Research examining the direct and indirect ecological effects of nanomaterials in aquatic ecosystems is important for developing a more realistic understanding of the environmental implications of nanotechnology. Copper oxide nanoparticles (CuO NPs) are being used extensively in many industries but are considered highly toxic to aquatic species residing in surface waters. Few studies have addressed whether CuO NPs can be transferred through the aquatic food chain, and if such indirect exposure to nanomaterials impacts their toxicity. We investigated the uptake and trophic transfer of CuO NPs from the algae Chlorella vulgaris to the crustacean Daphnia magna and assessed bio-partitioning and resulting toxicity. We hypothesized that CuO NPs can be associated with algal cells and be transported to predators through feeding, and that the chronic toxicity can be altered in comparison to direct CuO NP exposure. For the indirect feeding exposure, algae pre-incubated with CuO NPs (Cu-algae) were washed to remove loose NPs and fed to D. magna while Cu uptake and toxicity were evaluated. For the direct waterborne exposures, a parallel group of D. magna were exposed to equivalent concentrations of CuO NPs while being fed unexposed algae. Using hyperspectral imaging we observed strong surface associations between pre-incubated CuO NPs and algae used in the feeding exposure, and quantified the average Cu content (0.15mg Cu/L) with ICP-OES. Cu accumulated in daphnid bodies to a greater extent in direct exposures, whereas molted carapaces and neonate offspring had more copper following the indirect feeding exposure, implying that D. magna may regulate internal Cu differently depending on the method of CuO NP delivery. Significantly higher D. magna mortality was observed following direct exposure relative to feeding exposure, and neonate production from adult daphnids exposed indirectly to CuO NPs was significantly reduced. Thus, nanoparticle interaction with biota at one trophic level may alter the biological response at the next trophic level in a way that is dependent on the delivery scenario. This study highlights the importance of evaluating potential ecological impacts of nanomaterials in more relevant, complex exposure scenarios.
研究纳米材料在水生生态系统中的直接和间接生态效应，对于更现实地理解纳米技术对环境的影响至关重要。氧化铜纳米颗粒（CuO NPs）在许多行业中被广泛使用，但被认为对生活在地表水中的水生物种具有高毒性。很少有研究探讨CuO NPs是否能通过水生食物链转移，以及这种对纳米材料的间接暴露是否会影响其毒性。我们研究了CuO NPs从绿藻小球藻到甲壳动物大型溞的摄取和营养转移，并评估了生物分配和由此产生的毒性。我们假设CuO NPs可以与藻类细胞结合，并通过摄食传递给捕食者，并且与直接暴露于CuO NPs相比，其慢性毒性可能会发生改变。对于间接摄食暴露，将预先用CuO NPs孵育的藻类（铜藻）冲洗以去除松散的纳米颗粒，然后喂给大型溞，同时评估铜的摄取和毒性。对于直接水体暴露，一组平行的大型溞暴露于等效浓度的CuO NPs，同时喂食未暴露的藻类。使用高光谱成像，我们观察到预先孵育的CuO NPs与摄食暴露中使用的藻类之间有很强的表面结合，并通过电感耦合等离子体发射光谱法（ICP - OES）量化了平均铜含量（0.15mg铜/升）。在直接暴露中，铜在溞体中积累的程度更大，而在间接摄食暴露后，蜕壳和新生后代中的铜含量更多，这意味着大型溞可能根据CuO NPs的递送方式不同地调节体内的铜。相对于摄食暴露，直接暴露后观察到大型溞的死亡率显著更高，并且间接暴露于CuO NPs的成年溞产生的幼体数量显著减少。因此，纳米颗粒在一个营养级与生物群的相互作用可能会以一种依赖于递送情况的方式改变下一个营养级的生物反应。这项研究强调了在更相关、复杂的暴露情景中评估纳米材料潜在生态影响的重要性。
