Abstract Understanding potential effects of climate warming on biogeochemical cycling in freshwater ecosystems is of pressing importance. Specifically, increasing air and water temperatures could accelerate nutrient cycling in lakes, which has major implications for in-lake nutrient concentrations, water column nutrient stoichiometry, and downstream nutrient export. Lakes may respond differentially to warming based on their current trophic state, although direct comparisons of temperature-driven changes in nutrient cycling between low- and high-nutrient lakes are lacking. Here, we used an open-source coupled hydrodynamic biogeochemical model to simulate ecosystem-scale changes in water column total nitrogen (TN) and total phosphorus (TP) concentrations and TN:TP ratios due to potential incremental changes in air temperature (from +0 °C to +6 °C) in a low-nutrient and a high-nutrient lake. Warming resulted in lower TN and higher TP epilimnetic (surface water) concentrations in both lakes, resulting in reduced molar TN:TP ratios in both lakes. While the high- and low-nutrient lakes had similar magnitude reductions in TN:TP ratio between the +0 °C and +6 °C scenarios (30.3% and 34.6%, respectively), median epilimnetic TN:TP in the low-nutrient lake significantly decreased with as little as 1 °C of warming. Warming also altered net nutrient retention, with decreased downstream export of TN but increased downstream export of TP in both lakes. Our modeling results suggest that low-nutrient lakes may respond to warming at lower levels of temperature increase than high-nutrient lakes, and that climate warming could intensify effects of nutrient enrichment driven by increased N and P loading due to land-use change.

中文翻译：

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生态系统尺度养分循环对气温升高的反应因湖泊营养状态而异

摘要 了解气候变暖对淡水生态系统生物地球化学循环的潜在影响具有紧迫的重要性。具体而言，增加空气和水温可以加速湖泊中的养分循环，这对湖内养分浓度、水柱养分化学计量和下游养分输出具有重大影响。湖泊可能会根据其当前的营养状态对变暖做出不同的反应，尽管缺乏对低营养湖泊和高营养湖泊之间养分循环的温度驱动变化的直接比较。在这里，我们使用开源耦合水动力生物地球化学模型来模拟水体总氮 (TN) 和总磷 (TP) 浓度和 TN 的生态系统规模变化：由于低营养和高营养湖泊中气温的潜在增量变化（从 +0 °C 到 +6 °C），TP 比率。变暖导致两个湖泊的 TN 和 TP 流域（地表水）浓度降低，导致两个湖泊的 TN:TP 摩尔比降低。虽然在 +0 °C 和 +6 °C 情景之间，高营养和低营养湖泊的 TN:TP 比率下降幅度相似（分别为 30.3% 和 34.6%），但低营养湖泊中的中值流域 TN:TP仅升温 1°C，湖泊就会显着减少。变暖也改变了净养分保留，两个湖泊下游 TN 出口减少，但 TP 下游出口增加。我们的建模结果表明，与高营养湖泊相比，低营养湖泊可能会在较低的温度升高水平下对变暖做出反应，