Microorganism‐mediated nitrogen (N) cycling and dynamics are important functions of ecosystems, but such information is limited for high‐elevation rivers. This study analyzed the abundance and community structure of anammox and denitrifying bacteria and quantified N loss induced by these bacteria in five high‐elevation river sediments (including the Yellow River source region) on the Qinghai‐Tibet Plateau using high‐throughput sequencing and ¹⁵N‐labeling techniques. Anammox bacterial diversity was limited in these high‐elevation rivers, with Brocadia‐like species averagely accounting for 97.0% of anammox community composition. Several denitrifier nirS phylotypes were distributed across these high‐elevation rivers with high specificity, and the proportion of each of these phylotypes increased with elevation (p < 0.05). Stochastic processes such as dispersal limitation in denitrifying and anammox bacterial community assemblies were more important than environmental selection. Anammox and denitrification rates in the Yellow River source region were at the low end of their reported ranges in the literature on low‐elevation rivers. The high contribution of anammox to nitrogen loss (27% on average) in the Yellow River source region was likely assisted by DNRA (dissimilatory nitrate reduction to ammonium) and nitrification through supplying ammonium and nitrite, respectively, as substrate for the anammox reaction. The contribution of anammox to N₂ production was positively related to temperature (p < 0.05). Denitrification rates were more significantly affected by denitrifier community structure than environmental factors. This study suggests that anammox contribution to N loss should not be neglected in high‐elevation rivers, and community diversity should be considered when studying denitrification in high‐elevation rivers.

中文翻译：

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高海拔河流厌氧菌和反硝化细菌群落与氮损失率之间的联系

微生物介导的氮（N）循环和动力学是生态系统的重要功能，但此类信息仅限于高海拔河流。本研究使用高通量测序和¹⁵ N分析了青藏高原5个高海拔河床沉积物（包括黄河源区）中厌氧氨氧化和反硝化细菌的丰度和群落结构，并定量了这些细菌引起的氮损失。标签技术。在这些高海拔河流中，厌氧菌的细菌多样性受到限制，类Brocadia类物种平均占厌氧菌群落组成的97.0％。几种反硝化剂系统型以较高的特异性分布在这些高海拔河流上，并且每种系统型的比例都随着海拔的升高而增加（p  <0.05）。随机过程（例如反硝化和厌氧细菌群落中的扩散限制）比环境选择更为重要。黄河源区的厌氧氨氧化和反硝化率处于低海拔河流文献报道范围的低端。黄河源区厌氧氨氮对氮损失的高贡献（平均27％）可能是通过DNRA（将硝酸盐异化还原成铵）和通过分别提供铵和亚硝酸盐作为厌氧氨氮反应的底物来进行硝化作用。厌氧菌对N ₂的贡献生产与温度呈正相关（p < 0.05）。与环境因素相比，反硝化率受反硝化菌群落结构的影响更大。这项研究表明，在高海拔河流中，厌氧氨氮对氮素损失的贡献不容忽视，在研究高海拔河流的反硝化作用时，应考虑社区多样性。