College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, PR China.
Hunan International Scientific and Technological Cooperation Base of Agricultural Typical Pollution Remediation and Wetland Protection, College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Ecotoxicol Environ Saf. 2021 Aug;219:112312. doi: 10.1016/j.ecoenv.2021.112312. Epub 2021 May 11.
Copper (Cu) pollution is common in the soil. Due to the widespread application of TiO NPs, there is a high propensity for the co-occurrence of TiO nanoparticles (NPs) and Cu in agricultural soils. It is therefore imperative to evaluate the joint effects of TiO NPs and Cu on crops. In this study, the mutual effects of TiO NPs and Cu on their toxicity and accumulation in soybean seedlings and on their fates in a hydroponic system were determined. When Cu was at levels of 1 and 2 mg/L, the co-occurring TiO NPs at a non-toxic concentration (10 mg/L) significantly enhanced the toxicity and accumulation of Cu and Ti in soybeans, and inhibited the translocation of Cu from soybean roots to shoots. However, when the Cu concentration for co-exposure was ≥ 5 mg/L, such mutual effects disappeared. The amount of Cu ions adsorbed onto TiO NPs after 48 h of co-exposure gradually increased from 31 to 118 mg/g when the Cu concentration was increased from 1 to 20 mg/L. The aggregation and sedimentation of TiO NPs were significantly increased after 48 h of co-exposure with the Cu at a concentration higher than 5 mg/L, as compared to the single TiO NPs exposure. The increasing aggregation and sedimentation might reduce the bioavailability of TiO NPs associated with the adsorbed Cu to soybeans, and consequently alleviate or even neutralize the enhanced toxicity and accumulation of Cu in soybeans exerted by the co-existing TiO NPs. Our results thus suggest that consideration of the impact of TiO NPs on the phytotoxicity of heavy metals, and specifically Cu, needs to be interpreted with care, and highlight the importance of integrating the interaction and fates of TiO NPs and metals into their risk assessment.
铜（Cu）污染在土壤中很常见。由于 TiO NPs 的广泛应用，TiO 纳米颗粒（NPs）和 Cu 在农业土壤中共同存在的可能性很高。因此，评估 TiO NPs 和 Cu 对作物的联合效应是当务之急。在这项研究中，确定了 TiO NPs 和 Cu 对大豆幼苗毒性和积累的相互影响，以及它们在水培系统中的命运。当 Cu 浓度分别为 1 和 2 mg/L 时，非毒性浓度（10 mg/L）共存的 TiO NPs 显著增强了 Cu 和 Ti 在大豆中的毒性和积累，并抑制了 Cu 从大豆根部向地上部的转运。然而，当共暴露的 Cu 浓度≥5 mg/L 时，这种相互作用消失了。当 Cu 浓度从 1 增加到 20 mg/L 时，在共暴露 48 h 后，吸附到 TiO NPs 上的 Cu 离子的量逐渐从 31 增加到 118 mg/g。当 Cu 浓度高于 5 mg/L 时，TiO NPs 在共暴露 48 h 后，其聚集和沉淀明显增加，与单一 TiO NPs 暴露相比。增加的聚集和沉淀可能会降低与吸附的 Cu 相关的 TiO NPs 的生物利用度，从而减轻甚至中和共存的 TiO NPs 对大豆中 Cu 的增强毒性和积累。因此，我们的研究结果表明，考虑 TiO NPs 对重金属（特别是 Cu）的植物毒性的影响需要谨慎解释，并强调将 TiO NPs 和金属的相互作用和命运纳入其风险评估的重要性。
