Although more attention has been paid to microplastics (MPs) pollution in environment, research on the synthetic influence of microplastic and heavy metals remains limited. To help fill this information gap, we investigated the adsorption behavior of virgin polyvinyl chloride microplastics (PVCMPs) (≤450 µm white spherical powder) on cadmium (II). The effects on seed germination, seedling growth, photosynthetic system, oxidative stress indicators of lettuce, and changes in Cd bioavailability were evaluated under Cd (25 μmol/L), PVCMPs (200 mg/L), and PVCMP-Cd combined (200 mg/L + 25 μmol/L) exposures in hydroponic system. The results demonstrated that the PVCMPs effectively adsorbed Cd ions, which validated by the pseudo-second-order kinetic and the Langmuir isotherm models, indicating the sorption of Cd on the PVCMPs was primary chemisorption and approximates monomolecular layer sorption. Compared to MPs, Cd significantly inhibits plant seed germination and seedling growth and development. However, Surprising improvement in seed germination under PVCMPs-Cd exposure was observed. Moreover, Cd and MPs alone or combined stress caused oxidative stress with reactive oxygen species (ROS) including HO, O and Malondialdehyde (MDA) accumulation in plants, and substantially damaged to photosynthesis. With the addition of PVCMPs, the content of Cd in the leaves significantly (P<0.01) decreased by 1.76-fold, and the translocation factor and Cdremoval rate in the water substantially (P<0.01) decreased by 6.73-fold and 1.67-fold, respectively in contrast to Cd stress alone. Therefore, it is concluded the PVCMP was capable of reducing Cd contents in leaves, alleviating Cd toxicity in lettuce. Notably, this study provides a scientific foundation and reference for comprehending the toxicological interactions between microplastics and heavy metals in the environment.

中文翻译：

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微塑料对水培生菜 (Lactuca sativa L.) 中镉的毒性和去向影响


尽管环境中的微塑料（MPs）污染受到越来越多的关注，但对微塑料和重金属的综合影响的研究仍然有限。为了帮助填补这一信息空白，我们研究了原始聚氯乙烯微塑料 (PVCMP)（≤450μm 白色球形粉末）对镉 (II) 的吸附行为。评价Cd（25μmol/L）、PVCMPs（200mg/L）和PVCMP-Cd组合（200mg/L）对生菜种子萌发、幼苗生长、光合系统、氧化应激指标以及Cd生物有效性变化的影响。 /L + 25 μmol/L) 水培系统中的暴露。结果表明，PVCMPs能有效吸附Cd离子，并经准二级动力学和Langmuir等温线模型验证，表明PVCMPs对Cd的吸附为初级化学吸附，近似于单分子层吸附。与MPs相比，Cd显着抑制植物种子的萌发和幼苗的生长发育。然而，在 PVCMPs-Cd 暴露下，观察到种子发芽率得到了令人惊讶的改善。此外，Cd和MPs单独或联合胁迫会引起植物体内活性氧（ROS）包括H2O、O和丙二醛（MDA）积累的氧化应激，并严重损害光合作用。添加PVCMPs后，叶片中Cd含量显着降低（P<0.01）1.76倍，水中易位因子和Cd去除率显着降低（P<0.01）6.73倍和1.67倍，分别与单独的 Cd 应力对比。因此，PVCMP能够降低叶片中的Cd含量，减轻生菜中的Cd毒性。 值得注意的是，这项研究为理解环境中微塑料与重金属之间的毒理学相互作用提供了科学基础和参考。