College of Biology and the Environment, Nanjing Forestry University, Nanjing, Jiangsu 210037, China.
Department of Geography, McGill University, Montréal, QC H3A 0B9, Canada; Centre d'Études Nordiques, Université Laval, Québec, QC G1V 0A6, Canada.
Sci Total Environ. 2018 Jan 15;612:392-404. doi: 10.1016/j.scitotenv.2017.08.203. Epub 2017 Sep 1.
To quantify CO emissions from water surface of a reservoir that was shaped by flooding the boreal landscape, we developed a daily time-step reservoir biogeochemistry model. We calibrated the model using the measured concentrations of dissolved organic and inorganic carbon (C) in a young boreal hydroelectric reservoir, Eastmain-1 (EM-1), in northern Quebec, Canada. We validated the model against observed CO fluxes from an eddy covariance tower in the middle of EM-1. The model predicted the variability of CO emissions reasonably well compared to the observations (root mean square error: 0.4-1.3gCmday, revised Willmott index: 0.16-0.55). In particular, we demonstrated that the annual reservoir surface effluxes were initially high, steeply declined in the first three years, and then steadily decreased to ~115gCmyr with increasing reservoir age over the estimated "engineering" reservoir lifetime (i.e., 100years). Sensitivity analyses revealed that increasing air temperature stimulated CO emissions by enhancing CO production in the water column and sediment, and extending the duration of open water period over which emissions occur. Increasing the amount of terrestrial organic C flooded can enhance benthic CO fluxes and CO emissions from the reservoir water surface, but the effects were not significant over the simulation period. The model is useful for the understanding of the mechanism of C dynamics in reservoirs and could be used to assist the hydro-power industry and others interested in the role of boreal hydroelectric reservoirs as sources of greenhouse gas emissions.
为了量化因淹没北方景观而形成的水库水面的 CO 排放，我们开发了一个每日时间步长的水库生物地球化学模型。我们使用在加拿大魁北克省北部的年轻的北方水电水库东梅因-1（EM-1）中测量的溶解有机和无机碳（C）浓度来校准该模型。我们使用在 EM-1 中部的涡度协方差塔观测到的 CO 通量对模型进行了验证。与观测值相比，该模型对 CO 排放的可变性预测得相当好（均方根误差：0.4-1.3gCmday，修正的 Willmott 指数：0.16-0.55）。特别是，我们证明了水库表面的年排放通量起初很高，在最初的三年急剧下降，然后随着水库年龄的增长而稳定下降，在估计的“工程”水库寿命（即 100 年）期间，每年约为 115gCmyr。敏感性分析表明，空气温度的升高通过增强水柱和沉积物中的 CO 生成以及延长排放发生的开放水面期来刺激 CO 排放。增加淹没的陆地有机 C 的量可以增强底栖 CO 通量和水库水面的 CO 排放，但在模拟期间影响不显著。该模型有助于理解水库中 C 动态的机制，并可用于协助水电行业和其他对北方水电水库作为温室气体排放源的作用感兴趣的人。
