College of Environmental Science and Engineering, and Ministry of Education Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao 266100, China.
School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
Water Res. 2017 Mar 15;111:18-27. doi: 10.1016/j.watres.2016.12.037. Epub 2016 Dec 23.
We systematically investigated the toxicity mechanism of three graphene-family materials (GFMs), graphene oxide (GO), reduced graphene oxide (rGO) and multi-layer graphene (MG), to algae (Chlorella pyrenoidosa). GFMs exhibited much higher toxicity than other carbon materials (carbon nanotube and graphite), with the 96 h median effective concentration (EC) values of 37.3 (GO), 34.0 (rGO), and 62.2 (MG) mg/L. Shading effect contributed approximately 16.4% of growth inhibition by GO due to its higher dispersibility and transformation while the other GFMs did not show any shading effect. Hydrophobic rGO and MG more readily heteroagglomerated with algae than GO, thus likely leading to more direct contacts with algae. Flow cytometry results showed significant decrease of membrane integrity after GFM exposure, and rGO caused the highest membrane damage, which was confirmed by the increased DNA and K efflux. The observed membrane damage was caused by a combination of oxidative stress and physical penetration/extraction. Moreover, all the three GFMs could adsorb macronutrients (N, P, Mg, and Ca) from the algal medium, thus leading to nutrient depletion-induced indirect toxicity. GO showed the highest nutrient depletion (53% of total toxicity) due to its abundant functional groups. The information provided in this work will be useful for understanding toxicity mechanism and environmental risk of different GFMs in aquatic environments.
我们系统地研究了三种石墨烯家族材料（GFMs），氧化石墨烯（GO）、还原氧化石墨烯（rGO）和多层石墨烯（MG）对藻类（栅藻）的毒性机制。GFMs 表现出比其他碳材料（碳纳米管和石墨）更高的毒性，其 96 h 半有效浓度（EC）值分别为 37.3（GO）、34.0（rGO）和 62.2（MG）mg/L。由于 GO 具有更高的分散性和转化性，遮光效应约占 GO 生长抑制的 16.4%，而其他 GFMs 则没有表现出任何遮光效应。疏水性 rGO 和 MG 比 GO 更容易与藻类异质聚集，因此可能与藻类有更多的直接接触。流式细胞术结果表明，GFM 暴露后细胞膜完整性显著下降，rGO 导致的细胞膜损伤最大，这通过 DNA 和 K+外渗的增加得到了证实。观察到的膜损伤是由氧化应激和物理穿透/提取共同作用引起的。此外，三种 GFMs 都可以从藻类培养基中吸附大量营养物质（N、P、Mg 和 Ca），从而导致营养物质耗尽引起的间接毒性。由于其丰富的官能团，GO 表现出最高的营养物质耗尽（总毒性的 53%）。本工作提供的信息将有助于理解不同 GFMs 在水生环境中的毒性机制和环境风险。
