To better understand the contribution of alpine lakes to global CO₂ emissions, carbon dioxide concentrations and fluxes to the atmosphere were measured in five high‐elevation lakes and five reservoirs in the Sierra Nevada, California. Median summer surface concentrations of dissolved CO₂ (reservoirs: 21.1 μM, lakes: 23.7 μM) were supersaturated for most of the ice‐free season. Median diffusive flux of CO₂ was low as compared to other inland waters (lakes: 260 mg CO₂ m⁻² d⁻¹, reservoirs: 192 mg CO₂ m⁻² d⁻¹). Linear mixed modeling demonstrated that the length of ice cover, persisting for 5–9 months and allowing for accumulation of under‐ice CO₂, was a strong predictor of summer surface CO₂. During the ice‐free period, surface evasion of CO₂ was highest for the first 40 d after ice‐off when carbon dioxide that had accumulated during winter was released, although supersaturation and evasion continued until fall at most sites despite low rates of ecosystem metabolism. This study suggests that the contribution of high‐elevation, oligotrophic lakes and reservoirs in the Sierra to global CO₂ emissions are small despite persistent supersaturation, and are primarily driven by the duration of ice cover.

中文翻译：

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加利福尼亚内华达山脉的高海拔贫营养湖泊和水库中的二氧化碳过饱和

为了更好地了解高山湖泊对全球CO ₂排放的贡献，在加利福尼亚内华达山脉的五个高海拔湖泊和五个水库中测量了二氧化碳浓度和通向大气的通量。溶解的CO的平均夏表面浓度₂（水库：21.1 μ男，湖泊：23.7 μ M）进行过饱和对于大多数无冰季节。与其他内陆水域相比，CO _2的中值扩散通量较低（湖泊：260 mg CO ₂ m ^-2 d ^-1，水库：192 mg CO ₂ m ^-2 d ^-1）。线性混合模型表明，冰盖的持续时间为5-9个月，并允许冰下CO _2的积累，这是夏季表面CO ₂的强烈预测指标。在无冰时期，尽管生态系统新陈代谢率较低，但在大多数地方过饱和和回散一直持续到秋天，直到结冰后的头40 d ，CO _2的表面回散在冰后头40 d最高。 。这项研究表明，尽管持续过饱和，但塞拉利昂的高海拔，贫营养型湖泊和水库对全球CO ₂排放的贡献很小，并且主要受冰覆盖持续时间的驱动。