Because of their abundance and high emissions rates, small reservoirs (< 0.01 km2) can be important emitters of the greenhouse gases carbon dioxide and methane. However, emissions estimates from small reservoirs have lagged those of larger ones, and efforts to characterize small reservoir emissions have largely overlooked variations in emissions pathways, times, and locations. We intensively sampled four small reservoirs in Georgia, USA, during the summer to quantify the contribution and spatiotemporal variability of different emissions pathways (CO2 and CH4 diffusion, CH4 ebullition). We used these data to evaluate the efficiency and accuracy of different sampling schemes. Every emissions pathway was dominant in one reservoir on one sampling day, and excluding ebullition caused misestimation between −89% and −15% of the total flux. Sampling only once daily caused misestimation between −78% and 45%, but sampling twice or just after dawn (07:00 h) reduced error. Sampling four or fewer locations caused misestimation between −85% and 366%, and our results indicated that 6–20 sampling locations may be needed for reasonable accuracy. The floating aquatic macrophyte Wolffia sp. (duckweed) appeared to exert control over emissions variability, and the consequences of not accounting for variability were greater in a duckweed‐covered reservoir. Our results indicate that sampling only at 10:00 h (modal sampling time of prior efforts) may lead to the erroneous conclusion that reservoirs with high photosynthetic biomass are CO2 sinks rather than sources. Improving estimation accuracy by accounting for within‐reservoir variation in emissions will facilitate more strategic management of these abundant, anthropogenic ecosystems.

中文翻译：

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更准确地估计小型水库的碳排放

由于其丰富性和高排放率，小型水库（< 0.01 km2）可能是温室气体二氧化碳和甲烷的重要排放者。然而，小型水库的排放估算落后于大型水库的排放估算，并且描述小型水库排放特征的努力在很大程度上忽视了排放途径、时间和地点的变化。夏季，我们对美国佐治亚州的四个小型水库进行了集中采样，以量化不同排放途径（CO2和CH4扩散，CH4沸腾）。我们使用这些数据来评估不同采样方案的效率和准确性。在一个采样日，每一种排放途径在一个水库中都占主导地位，排除沸腾会导致总通量的错误估计在-89%到-15%之间。每天仅采样一次会导致 -78% 至 45% 之间的错误估计，但采样两次或在黎明后（07:00 h）采样可减少误差。对四个或更少的位置进行采样会导致 -85% 到 366% 之间的错误估计，我们的结果表明可能需要 6-20 个采样位置才能达到合理的精度。浮水大型植物枸杞属sp。 （浮萍）似乎对排放变异性施加了控制，并且在浮萍覆盖的水库中不考虑变异性的后果更大。我们的结果表明，仅在 10:00 小时（先前工作的模态采样时间）采样可能会导致错误的结论，即具有高光合生物量的水库是 CO22汇而不是源。通过考虑水库内排放量的变化来提高估计准确性将有助于对这些丰富的人为生态系统进行更具战略性的管理。