Environmental concerns regarding the potential ecological risks of metallic oxide nanoparticles (MNPs) in aquatic ecosystems are increasing; sediment is considered a sink for these MNPs. Although several studies have studied the potential impact of MNPs on microbial communities in freshwater and estuarine sediments, limited information is available regarding the influence of MNPs on the metabolic activity of surficial sediment microbial communities and related biogeochemical conditions. To address these issues, a microcosm approach was established to study the metabolic response of surficial sediment microbial communities to a single addition of TiO₂ or CeO₂ NPs (5 mg/L) using oxygen microelectrodes, enzyme activity measurements, and high-throughput sequencing. Rapid sedimentation of MNPs (regardless of NP type) was observed in freshwater samples, and most (up to 85%) accumulated in surface sediments (<5 mm). Microelectrode profile measurements in pre-incubated sediments treated with MNPs showed that the oxygen concentration decreased at a slower rate with increasing sediment depth compared to that in untreated controls. Biological oxygen consumption in the uppermost sediment layer (0–1500 μm) was significantly inhibited by MNPs, as calculated from steady-state microprofiles, with CeO₂ NPs resulting in enhanced acute toxicity than TiO₂ NPs. High-throughput sequencing showed that MNP exposure increased the bacterial diversity and altered the bacterial community structure, regardless of NP type. The abundance of three dominant bacterial genera, Methylotenera, Cytophagceae_uncultured (classified as an aerobic bacterium), and Cyanobacteria_norank (a facultative bacterium), was markedly reduced by MNPs, which was primarily responsible for inhibiting microbial-mediated oxygen consumption in surficial sediments. In summary, short-term exposure to MNPs negatively affected the metabolic activity of benthic microbial communities, which could influence the biogeochemical functions along the sediment-water interface.

有关水生生态系统中金属氧化物纳米颗粒（MNP）潜在生态风险的环境关注日益增加；沉积物被认为是这些MNP的汇。尽管一些研究已经研究了MNPs对淡水和河口沉积物中微生物群落的潜在影响，但是关于MNPs对表层沉积物微生物群落的代谢活性和相关生物地球化学条件的影响的信息有限。为了解决这些问题，建立了一种微观方法来研究表层沉积物微生物群落对TiO ₂或CeO ₂的单次添加的代谢反应。使用氧气微电极，酶活性测量和高通量测序的NP（5 mg / L）。在淡水样品中观察到MNP的快速沉降（无论NP类型如何），并且大部分（高达85％）沉积在表层沉积物中（<5 mm）。与未经处理的对照相比，在用MNPs处理的预温育沉积物中的微电极轮廓测量表明，随着沉积物深度的增加，氧浓度降低的速度较慢。从稳态微观剖面计算，MNP可以显着抑制最上层沉积物层（0-1500μm）中的生物耗氧量，其中CeO ₂ NPs的急性毒性比TiO ₂更高。NP。高通量测序表明，与NP类型无关，MNP暴露会增加细菌多样性并改变细菌群落结构。三大主导细菌属，丰Methylotenera，Cytophagceae_uncultured（分类为好氧性细菌）和Cyanobacteria_norank（兼性细菌），显着通过的MNP，这对于在表层沉积物抑制微生物介导的氧消耗主要负责减少。总之，短期接触MNP会对底栖微生物群落的代谢活性产生负面影响，这可能会影响沿沉积物-水界面的生物地球化学功能。