Snowmelt contributes a significant fraction of groundwater recharge in snow‐dominated regions, making its accurate quantification crucial for sustainable water resources management. While several components of the hydrological cycle can be measured directly, catchment‐scale recharge can only be quantified indirectly. Stable water isotopes are often used as tracers to estimate snowmelt recharge, even though estimates based on stable water isotopes are biased due to the large variations of δ²H and δ¹⁸O in snow and the difficulty to measure snowmelt directly. To overcome this gap, a new tracer method based on on‐site measurements of dissolved He, ⁴⁰Ar, ⁸⁴Kr, N₂, O₂, and CO₂ is presented. The new method was developed alongside classical tracer methods (stable water isotopes, ²²²Rn, ³H/³He) in a highly instrumented boreal catchment. By revealing (noble gas) recharge temperatures and excess air, dissolved gases allow (i) the contribution of snowmelt to recharge, (ii) the temporal recharge dynamics, and (iii) the primary recharge pathways to be identified. In contrast to stable water isotopes, which produced highly inconsistent snowmelt recharge estimates for the experimental catchment, dissolved gases produced consistent estimates even when the temperature of snowmelt during recharge was not precisely known. As dissolved gases are not controlled by the same processes as stable water isotopes, they are not prone to the same biases and represent a highly complementary tracer method for the quantification of snowmelt recharge dynamics in snow‐dominated regions. Furthermore, an observed systematic depletion of N₂ in groundwater provides new evidence for the pathways of biological N‐fixation in boreal forest soils.

中文翻译：

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通过现场溶解气体分析定量分析雪域集水区的地下水补给动力学和非饱和带过程

Snowmelt在以雪为主的地区为地下水的补给做出了很大的贡献，使其准确定量对于可持续水资源管理至关重要。虽然可以直接测量水文循环的几个组成部分，但流域规模补给只能间接地量化。稳定同位素水经常被用来作为示踪剂来估计融雪充值，即使基于稳定的水的同位素估计被偏置由于δ的大的变化² H和δ ¹⁸在雪O和直接测量融雪的难度。为了克服这一差距，基于现场测量溶解的He，⁴⁰ Ar，⁸⁴ Kr，N ₂，O ₂和CO的新示踪剂方法呈现₂。与经典示踪方法（稳定的水同位素，²²² Rn，³ H / ³他）处于高度仪器化的北方流域。通过显示（稀有气体）补给温度和过量空气，溶解的气体允许（i）融雪对补给的贡献，（ii）时间补给动态和（iii）识别主要补给途径。与稳定的水同位素相反，该同位素对实验集水区的融雪补给量估计高度不一致，即使无法精确知道补给过程中融雪的温度，溶解气体也会产生一致的估算值。由于溶解气体与稳定水同位素的控制方法不同，因此它们不易产生相同的偏差，因此代表了一种互补性示踪方法，用于量化以雪为主的地区的融雪补给动力学。此外，观察到的N的系统耗竭地下水中的₂提供了北方森林土壤中生物固氮途径的新证据。