During the flow of stream water from losing reaches through aquifer sediments, aerobic and anaerobic respiration (denitrification) can deplete dissolved oxygen and nitrate (NO₃⁻), impacting water quality in the floodplain and downstream gaining reaches. Such processes, which vary in time with short and long-term changes in stream flow and temperature, need to be assessed at the stream corridor scale to fully capture their effects on net turnover, but this has rarely been done. To address this gap, we combine a fully-integrated 3D transient numerical flow model with temperature-dependent reactive transport along advective subsurface flow paths to assess aerobic and anaerobic respiration dynamics at the stream corridor scale in a predominantly losing stream. Our results suggest that given carbon availability (as an electron donor), complete NO₃⁻ removal occurred further away from the stream after complete oxygen depletion and was relatively insensitive to variations in temperature and transit-times. Conversely, transit-times and oxygen concentrations constrained nitrate removal along short hyporheic flow paths. Even under limited carbon availability and low-temperatures, NO₃⁻ removal fractions () will be greater at locations further from the stream than along shorter hyporheic flow paths ( = 0.4 and  = 0.1, respectively). With increasing temperature, the relative effects of stream flow and solute concentrations on biogeochemical turnover and the redox zonation around the stream decreased. The study highlights the importance of seasonal variations of stream flow and temperature for water quality at the stream-corridor scale. It also provides an adaptive framework to assess and quantify reach-scale biogeochemical turnover around dynamic streams.

中文翻译：

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传输时间和温度控制河岸带有氧呼吸和反硝化的空间模式

在河流水流通过含水层沉积物的过程中，有氧和无氧呼吸（反硝化作用）会消耗溶解氧和硝酸盐（NO ₃ ^-)，影响泛滥平原和下游河段的水质。这些过程随着河流流量和温度的短期和长期变化而随时间变化，需要在河流走廊尺度上进行评估，以充分捕捉它们对净周转的影响，但很少有人这样做。为了解决这一差距，我们将完全集成的 3D 瞬态数值流模型与沿平流地下流动路径的温度相关反应输运相结合，以评估主要损失流中河流走廊尺度的有氧和无氧呼吸动力学。我们的结果表明，给定碳可用性（作为电子供体），完整的 NO ₃ ^-在完全耗尽氧气后，去除发生在远离流的地方，并且对温度和传输时间的变化相对不敏感。相反，传输时间和氧气浓度限制了沿短的低流流路径的硝酸盐去除。即使在有限的碳可用性和低的温度下，NO ₃ ^-除去部分（）将更大在从流中的位置进一步沿着较短的潜流流动路径（比 = 0.4和 = 0.1，分别）。随着温度升高，河流流量和溶质浓度对生物地球化学周转和河流周围氧化还原分带的相对影响减弱。该研究强调了河流流量和温度的季节性变化对河流走廊尺度的水质的重要性。它还提供了一个自适应框架来评估和量化动态流周围的范围生物地球化学周转。