Polystyrene microplastics (PS) and dibutyl phthalate (DBP) are emerging pollutants widely coexisting in agroecosystems. However, the efficacies of PS as carriers for DBP and their interactive mechanisms on crop safety remain scarce. Here, this study investigated the combined exposure effects and the interacting mechanisms of PS laden with DBP on choy sum (Brassica parachinensis L.). Results showed that PS could efficiently adsorb and carry DBP, with a maximum carrying capacity of 9.91 %, facilitating the chemical translocation of DBP in choy sum and exacerbating phytotoxicity. Due to the changes in the properties of PS, DBP loading aggravated the phytotoxicity of choy sum, exhibiting synergistically toxic effects compared with individual exposure. The Trojan-horse-complexes formed by PS+DBP severely delayed the seed germination process and altered spatial growth patterns, causing disruptions in oxidative stress, osmoregulation, photosynthetic function, and elemental reservoirs of choy sum. Combined pollutants enhanced the uptake and translocation of both PS and DBP by 8.90–31.94 % and 136.81–139.37 %, respectively; while the accumulation processes for PS were more complex than for DBP. Visualization indicated that PS was intensively sequestered in roots with a strong fluorescent signal after loading DBP. This study comprehensively investigated the efficacies of PS carrying DBP on phytotoxicity, bioavailability, and their interactive mechanisms, providing significant evidence for food safety assessment of emerging contaminant interactions.

中文翻译：

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聚苯乙烯微塑料促进邻苯二甲酸酯通过植物的化学过程并加重植物毒性


聚苯乙烯微塑料 （PS） 和邻苯二甲酸二丁酯 （DBP） 是农业生态系统中广泛共存的新兴污染物。然而，PS 作为 DBP 载体的功效及其对作物安全的交互机制仍然稀缺。在这里，本研究调查了富含 DBP 的 PS 对菜心 （Brassica parachinensis L.） 的联合暴露效应和相互作用机制。结果表明，PS 能高效吸附和携带 DBP，最大承载量为 9.91 %，有利于 DBP 在菜心中的化学易位，加剧植物毒性。由于 PS 性质的变化，DBP 负载加剧了菜心的植物毒性，与个体暴露相比表现出协同毒性作用。PS+DBP 形成的特洛伊木马复合物严重延缓了种子的发芽过程，改变了空间生长模式，导致菜心的氧化应激、渗透调节、光合功能和元素库的破坏。混合污染物使 PS 和 DBP 的吸收和转运分别提高了 8.90-31.94% 和 136.81-139.37%;而 PS 的积累过程比 DBP 更复杂。可视化表明，PS 在加载 DBP 后被强烈隔离在具有强荧光信号的根中。本研究全面考察了携带 DBP 的 PS 对植物毒性、生物利用度及其相互作用机制的疗效，为新出现的污染物相互作用的食品安全评估提供了重要证据。