Tropical floodplains are an important source of methane (CH₄) to the atmosphere, and ebullitive fluxes are likely to be important. We report direct measurements of CH₄ ebullition in common habitats on the Amazon floodplain over two years based on floating chambers that allowed detection of bubbles, and submerged bubble traps. Ebullition was highly variable in space and time. Of the 840 floating chamber measurements (equivalent to 8,690 min of 10-min deployments), 22% captured bubbles. Ebullitive CH₄ fluxes, measured using bubble traps deployed for a total of approximately 230 days, ranged from 0 to 109 mmol CH₄ m⁻² d⁻¹, with a mean of 4.4 mmol CH₄ m⁻² d⁻¹. During falling water, a hydroacoustic echosounder detected bubbles in 24% of the 70-m segments over 34 km. Ebullitive flux increased as the water level fell faster during falling water periods. In flooded forests, highest ebullitive fluxes occurred during falling water, while in open water and herbaceous plant habitats, higher ebullitive fluxes were measured during low water periods. The contribution of diffusive plus ebullitive CH₄ flux represented by ebullition varied from 1% (high and rising water in open water of the lake) to 93% (falling water in flooded forests) based on bubble traps. Combining ebullitive and diffusive fluxes among habitats in relation to variations in water depth and areal coverage of aquatic habitats provides the basis for improved floodplain-wide estimates of CH₄ evasion.

中文翻译：

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亚马逊洪泛区甲烷喷发的巨大季节性和栖息地差异

热带泛滥平原是大气中甲烷 (CH ₄ )的重要来源，沸腾通量可能很重要。我们报告了两年内在亚马逊洪泛区常见栖息地中 CH ₄沸腾的直接测量结果，这些测量结果基于可以检测气泡的浮舱和水下气泡陷阱。沸腾在空间和时间上是高度可变的。在 840 次浮舱测量中（相当于 10 分钟部署的 8,690 分钟），22% 的气泡被捕获。使用共部署约 230 天的气泡捕集器测量的沸腾 CH ₄通量范围为 0 至 109 mmol CH ₄ m ^-2  d ^-1，平均值为 4.4 mmol CH ₄ m^-2  d ^-1。在落水期间，水声测深仪在超过 34 公里的 70 米段中检测到 24% 的气泡。在落水期间，随着水位下降得更快，沸腾通量增加。在淹没的森林中，最高的沸腾通量发生在落水期间，而在开阔水域和草本植物栖息地，在低水期测量到更高的沸腾通量。扩散加沸腾 CH ₄的贡献基于气泡陷阱，以沸腾为代表的通量从 1%（湖泊开放水域的高水和上升水）到 93%（淹没森林中的下降水）不等。结合与水深变化和水生栖息地面积覆盖相关的栖息地之间的沸腾和扩散通量，为改进漫滩范围的 CH ₄逃逸估计提供了基础。