Iron flocculants play a major role in the remediation of water bodies, removing particulate pollutants such as microplastics through floc formation. Such flocs are prone to microbial iron reduction while lying on top of anoxic sediments, which possibly leads the release of bound microplastics. In this study, Shewanella oneidensis was employed to simulate the impact of microbial iron reduction on the release of polyethylene spheres from sunken flocs in 120 d batch experiments. Most of the flocs iron (oxyhydr)oxides were reduced (70–90%), but this did not affect their integrity. Only a negligible proportion (0.2–2.7%) of polyethylene spheres was released, while the majority remained bound inside the floc matrix. This study exemplifies that flocs are quite stable, even when experiencing microbial iron reduction under anoxic conditions. Thereby incorporation into such aggregates may display a potential mode of long-term microplastics storage in freshwater sediments.

中文翻译：

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微生物铁还原不会从有机金属聚集体中释放微塑料

铁絮凝剂在水体修复中发挥着重要作用，通过絮体形成去除微粒污染物，如微塑料。这种絮状物在缺氧沉积物上容易发生微生物铁还原，这可能导致结合的微塑料释放。在这项研究中，Shewanella oneidensis在 120 天的批量实验中，采用微生物铁还原对聚乙烯球从沉没的絮凝物中释放的影响进行了模拟。大多数絮状铁（氧氢）氧化物被还原（70-90%），但这并不影响它们的完整性。仅释放了可忽略不计的一部分（0.2-2.7%）聚乙烯球体，而大部分仍结合在絮凝体基质内。该研究举例说明，即使在缺氧条件下经历微生物铁还原时，絮凝物也非常稳定。因此，掺入这种聚集体中可能会显示出一种在淡水沉积物中长期储存微塑料的潜在模式。