The extensive application of graphene-family materials (GFMs) has increased its potential risk to aquatic organisms. However, the influence of humic acid (HA) on the biotoxicity of GFMs has not clarified. Here, we conduct a study on the toxicity of four GFMs, i.e. graphene (G), graphene oxide (GO), carboxyl-modified graphene (G-COOH) and amine-modified graphene (G-NH₂), with or without HA, using Scenedesmus obliquus (S. obliquus) as model organism. Our results showed that the four GFMs induced significant inhibition on cell growth and Chlorophyll-a (Chl-a) synthesis, loss of cell viability and membrane integrity as well as mitochondrial membrane potential (MMP), where G exhibited the highest toxicity with median effect concentration (EC₅₀) of 8.2 mg L⁻¹, and G-NH₂ exhibited the lowest toxicity with EC₅₀ of 84.0 mg L⁻¹. Meanwhile, HA mitigated the toxicity of GFMs in the order of G-NH₂ > G-COOH > GO > G for the most of endpoints. Furthermore, three possible mechanisms of the HA alleviation on toxicity were speculated as: (1) reduce the contact of GFMs with algae cells through regulating the structures and surface negative charges of GFMs; (2) mitigate physical penetration and damage through decreasing the deposition of GFMs on cells by interacting with HA; (3) react as an antioxidant with intracellular reactive oxygen species (ROS) and extracellular hydroxyl radical (

石墨烯家族材料（GFM）的广泛应用增加了其对水生生物的潜在风险。但是，腐殖酸（HA）对GFMs的生物毒性的影响尚不清楚。在这里，我们对四种GFM的毒性进行了研究，即带有或不带有HA的石墨烯（G），氧化石墨烯（GO），羧基改性石墨烯（G-COOH）和胺改性石墨烯（G-NH ₂） ，以斜Scene鱼（S. obliquus）作为模型生物。我们的结果表明，四种GFM对细胞生长和叶绿素a（Chl-a）合成，细胞活力和膜完整性以及线粒体膜电位（MMP）的诱导具有显着抑制作用，其中G表现出最高的毒性，具有中值作用浓度（EC ₅₀）8.2 mg L ^-1）和G-NH ₂表现出最低的毒性，EC ₅₀为84.0 mg L ^-1。同时， 对于大多数终点，HA按照G-NH ₂ > G-COOH> GO> G的顺序减轻了GFM的毒性。此外，推测HA减轻毒性的三种可能机理是：（1）通过调节GFM的结构和表面负电荷来减少GFM与藻类细胞的接触；（2）通过与HA相互作用减少GFM在细胞上的沉积，减轻物理渗透和破坏；（3）作为抗氧化剂与细胞内活性氧（ROS）和细胞外羟基自由基（