There is a critical knowledge gap about how glacier retreat in remote and rapidly warming tropical montane watersheds will impact solute export, which has implications for downstream geochemical cycling and ecological function. Because tropical glacierized watersheds are often uniquely characterized by year‐round ablation, upslope vegetation migration, and significant groundwater flow, baseline understanding is needed of how spatiotemporal variables within these watersheds control outlet hydrochemistry. We implemented a recently developed reactive transport watershed model, BioRT‐Flux‐PIHM, for a sub‐humid glacierized watershed in the Ecuadorian Andes with young volcanic soils and fractured bedrock. We found a unique simulated concentration and discharge (C‐Q) pattern that was mostly chemostatic but superimposed by dilution episodes. The chemostatic background was attributed to large simulated contributions of groundwater (subsurface lateral flow) to streamflow, of which a notable fraction (37%) comprised infiltrated ice‐melt. Relatively constant concentrations were further maintained in the model because times and locations of lower mineral surface wetting and dissolution were offset by concentrating effects of greater evapotranspiration. Ice‐melt did not all infiltrate in simulations, especially during large precipitation events, when high surface runoff contributions to discharge triggered dilution episodes. In a model scenario without ice‐melt, major ion concentrations, including Na⁺, Ca²⁺, and Mg²⁺, became more strongly chemostatic and higher, but weathering rates decreased, attenuating export by 23%. We expect this reduction to be exacerbated by higher evapotranspiration and drier conditions with expanded vegetation. This work brings to light the importance of subsurface meltwater flow, ecohydrological variability, and interactions between melt and precipitation for controlling hydrochemical processes in tropical watersheds with rapidly retreating glaciers.

中文翻译：

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安第斯山脉热带冰川流域中水化学变化的时空驱动因素

关于在偏远且迅速变暖的热带山地流域的冰川退缩将如何影响溶质的出口，存在着一个关键的知识鸿沟，这对下游的地球化学循环和生态功能产生了影响。由于热带冰川流域通常具有全年消融，上坡植被迁移和大量地下水流动的独特特征，因此需要对这些流域内的时空变量如何控制出口水化学进行基线了解。我们为厄瓜多尔安第斯山脉中一个湿润的冰川化分水岭实施了最新开发的反应运输分水岭模型，即BioRT-Flux-PIHM，火山岩土壤年轻，裂隙基岩破碎。我们发现了一个独特的模拟浓度和放电（C-Q）模式，该模式主要是趋化性的，但被稀释事件所叠加。趋化作用的本底归因于模拟的地下水（地下侧向流动）对水流的大量贡献，其中显着部分（37％）包括渗入的冰熔。在模型中进一步保持相对恒定的浓度，因为较低的矿物表面润湿和溶解的时间和位置被较大的蒸散作用的集中作用所抵消。在模拟过程中，冰融化并没有全部渗入，特别是在大型降水事件中，当高的地表径流量对排放的贡献触发了稀释事件。在没有融冰的模型场景中，主要的离子浓度（包括Na）在模型中进一步保持相对恒定的浓度，因为较低的矿物表面润湿和溶解的时间和位置被较大的蒸散作用的集中作用所抵消。在模拟过程中，冰融化并没有全部渗入，特别是在大型降水事件中，当高的地表径流量对排放的贡献触发了稀释事件。在没有融冰的模型场景中，主要的离子浓度（包括Na）在模型中进一步保持相对恒定的浓度，因为较低的矿物表面润湿和溶解的时间和位置被较大的蒸散作用的集中作用所抵消。在模拟过程中，冰融化并没有全部渗入，特别是在大型降水事件中，当高的地表径流量对排放的贡献触发了稀释事件。在没有融冰的模型场景中，主要的离子浓度（包括Na）⁺，Ca ²⁺和Mg ²⁺趋于更强的趋化性，并更高，但风化率降低，使出口减少23％。我们期望更高的蒸散量和更干燥的植被条件下的干旱会加剧这种减少。这项工作揭示了地下熔体水流量，生态水文变异性以及熔体与降水之间的相互作用对于控制具有快速后退冰川的热带流域的水化学过程的重要性。