Xiao Yunmu, Li Yong, Shi Yang, Li Ziqian, Zhang Xuyuan, Liu Ting, Farooq Taimoor Hassan, Pan Yuliang, Chen Xiaoyong, Yan Wende
National Engineering Laboratory for Applied Technology of Forestry & Ecology in South China, Laboratory of Urban Forest Ecology of Hunan Province, Life & Science Department, Central South University of Forestry and Technology, Changsha, Hunan, PR China.
National Engineering Laboratory for Applied Technology of Forestry & Ecology in South China, Laboratory of Urban Forest Ecology of Hunan Province, Life & Science Department, Central South University of Forestry and Technology, Changsha, Hunan, PR China.
Sci Total Environ. 2022 Feb 1;806(Pt 3):151211. doi: 10.1016/j.scitotenv.2021.151211. Epub 2021 Oct 27.
In recent years, nano-contamination in the soil environment has aroused concern. But it is still uncertain whether the interactions of nano- and metal-pollutants would have a combined toxic effect on plants. In this study, we investigated the effects of joint exposure to zinc oxide nanoparticles (ZnO NPs) and Cd on the root tissue of Phytolacca americana L. Spin-polarized density functional theory simulations assumed that the plant may undergo metal toxicity or acidosis upon joint exposure to ZnO NPs/Cd. Subsequently, experimental exposure of P. americana verified the combined toxic effects. The plant grew normally with a single treatment of ZnO NPs (500 mg/kg) or low doses of Cd (10 mg/kg). However, root growth was significantly inhibited with the combined treatments (up to 43% reduction); additionally, Cd ions were transported to the shoot, leading to shoot growth inhibition (translocation factor > 1). The antioxidant enzymes in the root (superoxide dismutase, peroxidase, and catalase) were highly activated to resist stress, accompanied by a greater than two-fold increase in thiobarbituric acid reactive substances. Corresponding to physiological indicators, biological transmission electron microscopy revealed severe damage to the root cells. Moreover, ZnO NPs/Cd accumulation was observed in the root cytoderm, which confirmed the toxicity of the combined effects. Our study provides insight into the potential combined toxicity of ZnO NPs and heavy metals in polluted environments, such as mining areas and electronic waste sites, and agricultural soils.
近年来，土壤环境中的纳米污染已引起关注。但纳米污染物与金属污染物的相互作用是否会对植物产生联合毒性作用仍不确定。在本研究中，我们调查了联合暴露于氧化锌纳米颗粒（ZnO NPs）和镉对美洲商陆根组织的影响。自旋极化密度泛函理论模拟假定，植物在联合暴露于ZnO NPs/镉时可能会发生金属毒性或酸中毒。随后，美洲商陆的实验暴露证实了联合毒性作用。单独处理ZnO NPs（500 mg/kg）或低剂量镉（10 mg/kg）时，植物生长正常。然而，联合处理时根生长受到显著抑制（最多减少43%）；此外，镉离子被转运到地上部分，导致地上部分生长受抑制（转运系数>1）。根中的抗氧化酶（超氧化物歧化酶、过氧化物酶和过氧化氢酶）被高度激活以抵抗胁迫，同时硫代巴比妥酸反应性物质增加了两倍以上。与生理指标相对应，生物透射电子显微镜显示根细胞受到严重损伤。此外，在根的细胞壁中观察到ZnO NPs/镉的积累，这证实了联合作用的毒性。我们的研究为了解ZnO NPs与重金属在污染环境（如矿区、电子垃圾场和农业土壤）中的潜在联合毒性提供了依据。
