Environmental controls on methane (CH₄) emission from lakes are poorly understood at subdaily time scales due to a lack of continuous data, especially for ebullition. We used a novel technique to partition eddy covariance CH₄ flux observed in the littoral zone of a midlatitude shallow lake in Japan and examined the environmental controls on diffusion and ebullitive CH₄ flux separately at a subdaily time scale in different seasons. Using the high‐frequency data, we investigated how CH₄ accumulation in the water and sediment layers alters the dynamics and environmental controls of fluxes. The contribution of ebullitive flux to total flux was 57% on average. Environmental controls of diffusive and ebullitive fluxes known in the literature were confirmed. We further found that the environmental controls were different in different seasons and suggested that additional consideration of CH₄ accumulation could explain the variability. The transfer of accumulated dissolved CH₄ from the bottom water layer to the surface in summer and the accumulation of dissolved CH₄ under surface ice in winter were suggested to be important for explaining the variability of diffusive flux. In summer, a higher ebullitive flux tended to occur following triggers such as a decrease in hydrostatic pressure. In winter, the impact of triggers was not obvious, and a higher ebullitive flux tended to occur in the morning. We suggested that the low CH₄ production rate in winter slowed the replenishment of bubbles in the sediment, negating the effect of triggers on ebullition.

中文翻译：

---

中纬度浅湖沿岸带亚尺度时间尺度下甲烷扩散扩散甲烷排放的环境控制

由于缺乏连续数据，特别是对于淡化，在次日尺度上对湖泊甲烷（CH ₄）排放的环境控制了解甚少。我们使用一种新技术来划分在日本中纬度浅湖沿岸带观察到的涡旋协方差CH ₄通量，并在不同季节的次日尺度上分别检查了扩散和沸腾CH ₄通量的环境控制。利用高频数据，我们研究了CH ₄水和沉积物层中的积累改变了通量的动力学和环境控制。沸腾通量对总通量的贡献平均为57％。确认了文献中已知的扩散和沸腾通量的环境控制。我们还发现，不同季节的环境控制有所不同，因此建议进一步考虑CH _4的积累可以解释其变异性。积累溶于CH转移₄从底部水层在夏季到表面并溶解CH积累₄冬季表层冰被认为对于解释扩散通量的变化很重要。夏季，在引发诸如静水压力降低等诱因后，往往会产生较高的沸腾通量。在冬季，触发器的影响并不明显，早晨倾向于产生更高的沸腾通量。我们建议冬季较低的CH ₄生产率减慢了沉积物中气泡的补充，从而消除了触发因素对沸腾的影响。