Abstract In constructed wetlands (CW), denitrification usually accounts for >60% of nitrogen removal and is supposedly affected by the inflow water and the wetland management practices. Fluctuations in nutrient concentration of inflow water can cause an impact in sediment properties and microbial communities living therein. We have estimated the effects of a high input of nitrate or nitrite (simulating an eutrophication event) on dissimilatory nitrite reduction by analysing the activities of nitrite reducing bacteria (denitrification and dissimilatory nitrite reduction to ammonia) at different C/N ratios in compartmentalized microcosms. Denitrification was always the predominant pathway for nitrite removal (>60%) and eventually led to the complete removal of nitrate. Dissimilatory nitrite reduction to ammonia was negatively affected by the input of nitrogen, and more severely due to a transient increase of nitrite. Analyses of the nir genes sequences based on DNA and cDNA analyses revealed the importance of uncultured phylotypes as main contributors to nitrite reduction in wetlands. Our results highlight a high recovery rate of the ecosystem service after a severe event of potential eutrophication and point to metabolic redundancy of denitrifiers.

中文翻译：

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不同C/N比下高硝酸盐输入对人工湿地沉积物中反硝化-DNRA活性的影响

摘要 在人工湿地 (CW) 中，反硝化通常占脱氮量的 60% 以上，并且据推测受到流入水和湿地管理实践的影响。流入水中养分浓度的波动会影响沉积物特性和生活在其中的微生物群落。我们通过分析亚硝酸盐还原细菌（反硝化作用和异化亚硝酸盐还原为氨）的活性，估计了高输入硝酸盐或亚硝酸盐（模拟富营养化事件）对不同 C/N 比的亚硝酸盐还原的影响。反硝化一直是去除亚硝酸盐（>60%）的主要途径，并最终导致完全去除硝酸盐。氮的输入会对异化亚硝酸盐还原为氨产生负面影响，更严重的是由于亚硝酸盐的瞬时增加。基于 DNA 和 cDNA 分析的 nir 基因序列分析揭示了未培养的系统发育型作为湿地亚硝酸盐减少的主要贡献者的重要性。我们的结果突出了在潜在富营养化的严重事件后生态系统服务的高恢复率，并指出了反硝化菌的代谢冗余。