Methane oxidation in lakes removes a large portion of methane (CH₄). To date, methane oxidation estimates in lakes have often been derived at low spatial resolution in the water column, preventing understanding of the links to the physicochemical gradients in the stratified regions. We applied a mass balance approach with measured dissolved CH₄ and sediment CH₄ fluxes to derive high-resolution depth profiles of specific CH₄ oxidation rates ($k_{\mathrm{ox}}$) in the water column during the stratified period of a small eutrophic lake (Soppensee, Switzerland). Estimated $k_{\mathrm{ox}}$ ranged from 0 to 1 d⁻¹ and the $k_{\mathrm{ox}}$ profiles agreed well with previous studies, and were also in agreement with rates from concurrent in situ oxidation experiments. A sensitivity analysis revealed that sediment CH₄ flux is the largest source of uncertainty when deriving k_ox. Although previous studies have estimated methane oxidation based on δ¹³C_CH4, we showed with numerical modeling that δ¹³C_CH4 measurements could not be used to resolve the relative contributions of methane oxidation and sediment fluxes to the water column CH₄ balance. Exploration of alternative approaches to derive methane oxidation is needed to reveal potentially unknown or misunderstood drivers of methane oxidation in lakes. The presented mass balance approach has the potential to calculate methane oxidation at high vertical resolution and enhance the spatial limitations of established incubation methods. As methane oxidation is responsible for removing most of the produced methane in lakes, it is as important to accurately resolve the key drivers to predict responses to future climate scenarios.

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分层湖中的甲烷氧化动力学：从质量平衡和碳稳定同位素揭示的见解

湖泊中的甲烷氧化去除了大部分甲烷（CH ₄）。迄今为止，湖泊中的甲烷氧化估计通常是在水柱中的低空间分辨率下得出的，从而妨碍了理解与分层区域中物理化学梯度的联系。我们应用质量平衡方法测量溶解的 CH ₄和沉积物 CH _{4通量，以得出特定 CH 4}氧化速率的高分辨率深度剖面（${ķ}_{牛}$) 在一个小型富营养化湖 (Soppensee, 瑞士) 的分层期间的水柱中。估计的${ķ}_{牛}$范围从 0 到 1 d ^-1和${ķ}_{牛}$剖面与以前的研究一致，并且也与同时进行的原位氧化实验的速率一致。敏感性分析表明，沉积物 CH ₄通量是推导k _ox时最大的不确定性来源。虽然之前的研究已经基于 δ ¹³ C _CH4估计了甲烷氧化，但我们通过数值模拟表明，δ ¹³ C _CH4测量不能用于解决甲烷氧化和沉积物通量对水柱 CH _{4的相对贡献}平衡。需要探索获得甲烷氧化的替代方法，以揭示湖泊中甲烷氧化的潜在未知或误解驱动因素。所提出的质量平衡方法有可能以高垂直分辨率计算甲烷氧化，并增强已建立的孵化方法的空间限制。由于甲烷氧化负责去除湖泊中产生的大部分甲烷，因此准确解决关键驱动因素以预测对未来气候情景的响应同样重要。