The recovery phase of mangrove seedlings in coastal wetland ecosystems can be negatively affected by exposure to external pollutants. This study aimed to investigate the impact of microplastics (MPs) influx, specifically polystyrene (PS) and polymethyl methacrylate (PMMA), on the growth of seedlings and their accumulation of heavy metals (HMs). PS and PMMA significantly increased HMs accumulation (up to 21.0–548%), particularly in the roots of seedlings, compared to the control treatment (CK). Additionally, elevated activities of malondialdehyde and catalase enzymes were observed in the leaves of seedlings, while peroxidase enzyme activity decreased. Topological analysis of the root sediment microbiota coexistence network revealed that the modularization data increased from 0.69 (CK treatment) to 1.07 (PS treatment) and 5.11 (PMMA treatment) under the combined stress of MPs and HMs. This suggests that the introduction of MPs intensifies microbial modularization. The primary cause of increased HMs accumulation in plants is the MPs input, which influences the secretion of organic acids by plants and facilitates the shift of HMs in sediment to bioavailable states. Furthermore, changes in microbial clustering may also contribute to the elevated HMs accumulation in plants. This study provides valuable insights into the effects of external pollutants on mangrove seedlings and offers new perspectives for the preservation and restoration of mangrove coastal wetlands.

中文翻译：

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由于微塑料流入，沿海湿地环境中红树幼苗重金属积累的风险增加

沿海湿地生态系统中红树林幼苗的恢复阶段可能会受到外部污染物暴露的负面影响。本研究旨在调查微塑料（MP）的流入，特别是聚苯乙烯（PS）和聚甲基丙烯酸甲酯（PMMA）对幼苗生长及其重金属（HM）积累的影响。与对照处理 (CK) 相比，PS 和 PMMA 显着增加了 HMs 积累（高达 21.0-548%），特别是在幼苗根部。此外，在幼苗叶片中观察到丙二醛和过氧化氢酶活性升高，而过氧化物酶活性降低。根沉积物微生物共存网络的拓扑分析表明，在MPs和HMs的联合胁迫下，模块化数据从0.69（CK处理）增加到1.07（PS处理）和5.11（PMMA处理）。这表明 MP 的引入强化了微生物模块化。植物体内HMs积累增加的主要原因是MPs的输入，它影响植物有机酸的分泌，促进沉积物中HMs向生物可利用状态的转变。此外，微生物簇的变化也可能导致植物中重金属积累的增加。该研究为外部污染物对红树林幼苗的影响提供了有价值的见解，并为红树林滨海湿地的保护和恢复提供了新的视角。