Glaciated environments have been highlighted as important sources of bioavailable nutrients, with inputs of glacial meltwater potentially influencing productivity in downstream ecosystems. However, it is currently unclear how riverine nutrient concentrations vary across a spectrum of glacial cover, making it challenging to accurately predict how terrestrial fluxes will change with continued glacial retreat. Using 40 rivers in Chilean Patagonia as a unique natural laboratory, we investigate how glacial cover affects riverine Si and Fe concentrations, and infer how exports of these bioessential nutrients may change in the future. Dissolved Si (as silicic acid) and soluble Fe (<0.02 μm) concentrations were relatively low in glacier‐fed rivers, whereas concentrations of colloidal‐nanoparticulate (0.02–0.45 μm) Si and Fe increased significantly as a function of glacial cover. These colloidal‐nanoparticulate phases were predominately composed of aluminosilicates and Fe‐oxyhydroxides, highlighting the need for size‐fractionated analyses and further research to quantify the lability of colloidal‐nanoparticulate species. We also demonstrate the importance of reactive particulate (>0.45 μm) phases of both Si and Fe, which are not typically accounted for in terrestrial nutrient budgets but can dominate riverine exports. Dissolved Si and soluble Fe yield estimates showed no trend with glacial cover, suggesting no significant change in total exports with continued glacial retreat. However, yields of colloidal‐nanoparticulate and reactive sediment‐bound Si and Fe were an order of magnitude greater in highly glaciated catchments and showed significant positive correlations with glacial cover. As such, regional‐scale exports of these phases are likely to decrease as glacial cover disappears across Chilean Patagonia, with potential implications for downstream ecosystems.

中文翻译：

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冰川覆盖对智利巴塔哥尼亚河流河流硅和铁出口的影响

冰川环境已被强调为生物可利用营养的重要来源，而冰川融水的输入可能会影响下游生态系统的生产力。但是，目前尚不清楚河流营养素浓度在整个冰川覆盖范围内如何变化，因此难以准确预测随着冰川的不断退缩，地面通量将如何变化。我们利用智利巴塔哥尼亚的40条河流作为独特的天然实验室，我们研究了冰川覆盖如何影响河流中的硅和铁的浓度，并推断出这些生物必需养分的出口将来可能如何变化。固溶Si（如硅酸）和可溶性的Fe（< 0.02  μ米）浓度在冰川喂养河流比较低，而胶态纳米微粒（0.02-0.45的浓度 μ M）Si和Fe作为冰覆盖的函数显著增加。这些胶体-纳米颗粒相主要由硅铝酸盐和羟基氧化铁组成，这凸显了进行粒度分级分析和定量研究胶体-纳米颗粒物种不稳定性的必要性。我们还表明反应性颗粒的重要性（> 0.45  μm）硅和铁的阶段，这通常不在陆地营养预算中考虑，但可以主导河流的出口。溶解的硅和可溶的铁的产量估计没有显示出冰川覆盖的趋势，这表明随着冰川的退缩，总出口量没有显着变化。但是，在高度冰川化的流域，胶体-纳米颗粒和反应性沉积物结合的硅和铁的产量要高一个数量级，并且与冰川覆盖度呈显着正相关。这样，随着智利巴塔哥尼亚冰川覆盖的消失，这些阶段的区域规模出口可能会减少，这可能对下游生态系统产生影响。