Ponds are regarded as greenhouse gas (GHG) emission hot spots, but how hot are they? We examined this question by measuring methane (CH₄) and carbon dioxide (CO₂) fluxes in six forest and open land ponds on grasslands in Denmark during summer and winter. We used floating chambers with do-it-yourself sensors and automated headspace venting, allowing for 7404 hourly measurements. We found highly variable gas fluxes within ponds and between seasons and pond types. Ebullitive CH₄ fluxes were more variable than diffusive CH₄ fluxes. Ebullition was absent when total CH₄ fluxes were lowest (15 µmol m⁻² h⁻¹), dominant (> 90%) at the highest fluxes (> 400 µmol m⁻² h⁻¹), and increased with water temperature. In summer, a minor daily increase in diffusive fluxes was found on days with high wind speed, while CH₄ ebullition remained constant. CO₂ fluxes paralleled the day-night balance of photosynthesis and respiration. Mean CH₄ ebullition in open and forest ponds exceeded CH₄ diffusive fluxes 4.1 and 7.1-fold in summer (avg. 22.5 °C) and 2.3 and 2.5-fold in winter (9.6 °C), respectively. CO₂ emissions were higher on a molar basis than CH₄ emissions, both in summer and winter, while their annual global warming potentials were similar. Mean annual gas emissions from open and forest ponds (1092 and 2527 g CO₂e m⁻² y⁻¹) are naturally high due to extensive external input of dissolved CO₂ and organic carbon relative to pond area and volume.

池塘被视为温室气体（GHG）排放热点，但它们到底有多热？我们通过测量夏季和冬季丹麦六个森林和草原上开阔地池塘的甲烷 (CH ₄ ) 和二氧化碳 (CO _{2 ) 通量来研究这个问题。}我们使用带有 DIY 传感器和自动顶空通风的浮动室，每小时可进行 7404 次测量。我们发现池塘内以及季节和池塘类型之间的气体通量变化很大。沸腾CH _{4通量比扩散CH 4}通量变化更大。_{当总CH 4}通量最低（15 µmol m ^-2  h ^-1 ）时不存在沸腾，在最高通量（> 400 µmol m ^-2  h ^-1）时占主导地位（> 90%），并且随着水温的增加而增加。夏季，在高风速的日子里，扩散通量每日略有增加，而 CH ₄沸腾保持恒定。CO ₂通量与光合作用和呼吸的昼夜平衡平行。露天和森林池塘的平均CH ₄沸腾在夏季（平均22.5 °C）分别超过CH _{4扩散通量4.1 和7.1 倍，在冬季（平均9.6 °C）分别超过2.3 和2.5 倍。}无论是夏季还是冬季，按摩尔计算， CO ₂排放量都高于 CH ₄排放量，而它们的年全球变暖潜势相似。_{由于相对于池塘面积和体积而言，溶解CO 2}和有机碳的大量外部输入，露天池塘和森林池塘的平均年气体排放量（1092 和2527 g CO ₂ e m ^-2  y ^-1）自然较高。