The effects of metallic nanoparticles (NPs) on the estuarine biota have mostly been shown for concentrations higher than those actually measured or predicted in these environments. To address this gap, a range of concentrations expected to occur in estuarine environments (from 0.01 to 1 μg g⁻¹) was employed in microcosms studies to assess the impact of Cu NPs in the denitrification pathway. This was achieved by quantifying the gene expression in estuarine sediments exposed to Cu NPs for up to six days and potential denitrification rates. The expression of nitrite (nirS) and nitrous oxide (nosZ) reductase genes was enhanced in a timewise manner upon exposure to Cu NPs <50 nm. For 1 μg g⁻¹ Cu NPs, an increase in the gene expression could be seen immediately after 1 h of exposure and continued to be enhanced up to 7 h. For 0.01 μg g⁻¹ Cu NPs, an increase in the gene expression could only be seen after 4 h or 7 h of exposure; however, it continued to rise until 24 h. Concomitantly to the increased gene expression, the potential denitrification rate was increased by 30%. In any case, after 48 h, expression levels were no longer different from that of the non-exposed control. For the exposure to Cu NPs <150 nm, no change in the gene expression could be seen. Our results suggest that the deposition and adsorption of Cu NPs <50 nm in estuarine sediments promote the immediate and transient expression of key genes of the denitrification pathway. The long-term impact of continuous inputs of Cu NPs into estuaries deserves renewed analysis to account for their effects not just on the biota but especially on ecosystem functions.

中文翻译：

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新兴研究者系列：在相关环境浓度下，河口反硝化细菌群落对铜纳米颗粒的迅速反应

在高于这些环境中实际测量或预测的浓度的情况下，大多数已证明了金属纳米颗粒（NPs）对河口生物的影响。为了解决这一差距，在微观研究中采用了预期在河口环境中发生的一系列浓度范围（从0.01到1μgg ^-1）来评估Cu NP在反硝化途径中的影响。这是通过量化暴露于铜纳米颗粒长达六天的河口沉积物中的基因表达和潜在的反硝化率来实现的。暴露于<50 nm的Cu NPs后，亚硝酸盐（nirS）和一氧化二氮（nosZ）还原酶基因的表达随时间增加。对于1μgg ^-1Cu NPs，在暴露1 h后立即可见到基因表达的增加，直至7 h持续增强。对于0.01μgg ^-1Cu NPs，仅在暴露4 h或7 h后才能看到基因表达的增加；但是，它持续上升直到24小时。伴随基因表达的增加，潜在的反硝化率增加了30％。无论如何，在48小时后，表达水平与未暴露的对照不再相同。对于暴露于＜150nm的Cu NPs，看不到基因表达的变化。我们的结果表明，河口沉积物中Cu NPs <50 nm的沉积和吸附促进了反硝化途径关键基因的即时和瞬时表达。不断向河口输入铜纳米颗粒的长期影响值得重新分析，以说明它们不仅对生物区系，而且对生态系统功能的影响。