Process-specific inhibition of sediment denitrification by metal oxide nanoparticles.

Nanoparticles selectively inhibit sediment denitrification pathways, with nZnO reducing heterotrophic denitrification by 11.6% and iron-based autotrophic denitrification by 38.7%.

• Why it matters: Understanding how nanoparticles affect nitrogen cycling in sediments is crucial because their accumulation may disrupt ecosystem functions and nutrient removal processes.
• What they did: The study examined the effects of nZVI, nCuO, and nZnO on three denitrification processes in sediment, analyzing enzyme activities, microbial communities, and gene abundance through integrated methods.
• The result: Findings show process- and particle-specific toxicity, with nZnO causing the strongest inhibition, and highlight that enzyme activity and gene abundance may be decoupled, suggesting ecological risk assessments need to consider multiple biological indicators.