Rivers denitrify a portion of their nitrate () load, but estimates are difficult using microcosm or reach‐scale measurements that require specific biogeochemical and hydrologic conditions. Measuring reach‐scale oxygen (O₂) respiration fluxes is easier than nitrogen (N₂) fluxes, thus we paired microcosm estimates of denitrification by N₂ production with estimates of aerobic respiration. The median molar ratio of ΔN₂:−ΔO₂ from 13 streams was 0.011 (95% credible interval 0.0002–0.027 mol:mol). We then measured diel O₂ concentrations from 11 streams and converted to ecosystem respiration (ER) using a multiday oxygen model. Given reach‐scale ER of −160 mmol O₂ m⁻² d⁻¹, the estimated median denitrification was 1.5 mmol N₂ m⁻² d⁻¹ (credible interval (CI): 0.18–4.21) across our streams. Our estimates of denitrification constituted 19% of gross uptake (CI: 0–51%). In streams, ΔN₂:−ΔO₂ was lower than in estuarine and marine ecosystems. Despite multiple sources of error, this approach estimates reach‐scale denitrification and variation with concentrations.

中文翻译：

---

将反硝化与山区河流的生态系统呼吸联系起来

河流反硝化了一部分硝酸盐（），但要使用需要特定生物地球化学和水文条件的微观或规模测量很难进行估算。测量可达范围的氧气（O ₂）呼吸通量比氮（N ₂）通量更容易，因此我们将通过N ₂产生的反硝化微观估算与需氧呼吸估算结合在一起。ΔN的中位摩尔比₂：-ΔO ₂从13流为0.011（95％置信区间0.0002-0.027摩尔：摩尔）。然后，我们测量了11条溪流中diel O _2的浓度，并使用多天氧气模型将其转换为生态系统呼吸（ER）。给定ER为−160 mmol O _2时m ^-2 d ^-1，估计整个流中的反硝化中位数为1.5 mmol N ₂ m ^-2  d ^-1（可信区间（CI）：0.18–4.21）。我们对反硝化作用的估计占总摄入量的19％（CI：0–51％）。在溪流，ΔN ₂：-ΔO ₂比在河口和海洋生态系统低。尽管有多种误差来源，但这种方法仍能估算出反硝化作用的范围以及浓度的变化。