Freshwater lakes are increasingly recognized as significant sources of atmospheric methane (CH₄), potentially offsetting the terrestrial carbon sink. We present the first study of dissolved CH₄ distributions and lake-air flux from Lake Winnipeg, based on two-years of observations collected during all seasons. Methane concentrations across two years had a median of value of 24.6 nmol L^-1 (mean: 41.6 ± 68.2 nmol L^-1) and ranged between 5.0 and 733.8 nmol L^-1, with a 2018 annual median of 24.4 nmol L^-1 (mean: 46.8 ± 99.3 nmol L^-1) and 25.1 nmol L^-1 (mean: 38.8 ± 45.2 nmol L^-1) in 2019. The median lake-air flux was 1.1 µmol m⁻² h⁻¹ (range: 0.46–70.1 µmol m⁻²h⁻¹, mean: 2.9 ± 10.2 µmol m⁻² h⁻¹) in 2018, and 5.5 µmol m⁻²h⁻¹ (range: 0.0–78.4 µmol m⁻² h⁻¹, mean: 2.7 ± 8.5 µmol m⁻² h⁻¹) in 2019, for a total diffusive emission of 0.001 Tg of CH₄-C yr⁻¹. We found evidence of consistent spatial variability, with higher concentrations near river inflows. Significant seasonal trends in CH₄ concentrations were not observed, though fluxes were highest during the fall season due to strong winds. Our findings suggest Lake Winnipeg is a CH₄ source of similar mean magnitude to Lake Erie, with lower concentrations and fluxes per unit area than smaller mid- to high-latitude lakes. Additional work is needed to understand the factors underlying observed spatial variability in dissolved gas concentration, including estimations of production and consumption rates in the water column and sediments.

淡水湖越来越被认为是大气甲烷 (CH ₄ ) 的重要来源，有可能抵消陆地碳汇。我们根据在所有季节收集的两年观测资料，首次对来自温尼伯湖的溶解 CH ₄分布和湖-空气通量进行了研究。两年间甲烷浓度的中值为 24.6 nmol L ^-1（平均值：41.6 ± 68.2 nmol L ^-1），范围在 5.0 到 733.8 nmol L ^{-1 之间}，2018 年的年度中值为 24.4 nmol L ^-1 (平均值：46.8 ± 99.3 nmol L ^-1）和 25.1 nmol L ^-1（平均值：38.8 ± 45.2 nmol L ^-1) 在 2019 年。2018 年的中值湖泊空气通量为 1.1 µmol m ^-2 h ^-1（范围：0.46–70.1 µmol m ^-2 h ^-1，平均值：2.9 ± 10.2 µmol m ^-2 h ^-1），和2019 年为5.5 µmol m ^-2 h ^-1（范围：0.0–78.4 µmol m ^-2 h ^-1，平均值：2.7 ± 8.5 µmol m ^-2 h ^-1），总扩散发射为 0.001 Tg CH ₄ - C yr ^-1。我们发现了一致的空间变异性的证据，河流入流附近的浓度较高。CH _{4 的}显着季节性趋势没有观察到浓度，但由于强风，秋季通量最高。我们的研究结果表明，温尼伯湖是一个与伊利湖平均震级相似的 CH ₄源，与较小的中高纬度湖泊相比，单位面积的浓度和通量较低。需要开展更多工作来了解所观察到的溶解气体浓度空间变异性的潜在因素，包括对水体和沉积物的生产和消耗率的估计。