Microplastics (MPs) have attracted increasing attention due to their ubiquitous occurrence in freshwater sediments and the detrimental effects on benthic invertebrates. However, a clear understanding of their downstream impacts on ecosystem services is still lacking. This study examines the effects of bio-based polylactic acid (PLA), fuel-based polyethylene terephthalate (PET), and biofilm-covered PET (BPET) MPs on the bioturbator chironomid larvae (), and the influence on phosphorus (P) profiles in microcosms. The changes in biochemical responses and metabolic pathways indicated that MPs disrupted energy synthesis by causing intestinal blockage and oxidative stress in , leading to energy depletion and impaired bioturbation activity. The impairment further resulted in enhanced sedimentary P immobilization. For larval treatments, the internal-P loadings were respectively 11.4%, 8.6%, and 9.0% higher in the PLA, PET, and BPET groups compared to the non-MP control. Furthermore, the influence of bioturbation on P profiles was MP-type dependent. Both BPET and PLA treatments displayed more obvious impacts on P profiles compared to PET due to the changes in MP bioavailability or sediment microenvironment. This study connects individual physiological responses to broader ecosystem services, showing that MPs alter P biogeochemical processes by disrupting the bioturbation activities of chironomid larvae.

中文翻译：

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关于微塑料对沉积物-水界面磷分布变化的新见解：底栖生物扰动的作用

微塑料（MP）因其在淡水沉积物中普遍存在以及对底栖无脊椎动物的有害影响而引起了越来越多的关注。然而，仍然缺乏对其下游对生态系统服务影响的清晰了解。本研究探讨了生物基聚乳酸 (PLA)、燃料基聚对苯二甲酸乙二醇酯 (PET) 和生物膜覆盖的 PET (BPET) MP 对生物扰动摇蚊幼虫 () 的影响，以及对磷 (P) 分布的影响在微观世界中。生化反应和代谢途径的变化表明MPs通过引起肠道阻塞和氧化应激来破坏能量合成，导致能量消耗和生物扰动活性受损。这种损伤进一步导致沉积物磷固定作用增强。对于幼虫处理，与非 MP 对照组相比，PLA、PET 和 BPET 组的内部磷负荷分别高 11.4%、8.6% 和 9.0%。此外，生物扰动对 P 分布的影响取决于 MP 类型。由于 MP 生物利用度或沉积物微环境的变化，与 PET 相比，BPET 和 PLA 处理对 P 谱的影响更为明显。这项研究将个体的生理反应与更广泛的生态系统服务联系起来，表明 MP 通过破坏摇蚊幼虫的生物扰动活动来改变磷的生物地球化学过程。