Electricité de France, Hydro Engineering Centre, Risk and Sustainable Development Dpt, Savoie Technolac, F-73373 Le Bourget du Lac, France.
Sci Total Environ. 2011 Nov 15;409(24):5382-91. doi: 10.1016/j.scitotenv.2011.09.018. Epub 2011 Sep 29.
Gross CO2 and CH4 emissions (degassing and diffusion from the reservoir) and the carbon balance were assessed in 2009-2010 in two Southeast Asian sub-tropical reservoirs: the Nam Ngum and Nam Leuk Reservoirs (Lao PDR). These two reservoirs are within the same climatic area but differ mainly in age, size, residence time and initial biomass stock. The Nam Leuk Reservoir was impounded in 1999 after partial vegetation clearance and burning. However, GHG emissions are still significant 10 years after impoundment. CH4 diffusive flux ranged from 0.8 (January 2010) to 11.9 mmol m(-2) d(-1) (April 2009) and CO2 diffusive flux ranged from -10.6 (October 2009) to 38.2 mmol m(-2) d(-1) (April 2009). These values are comparable to other tropical reservoirs. Moreover, degassing fluxes at the outlet of the powerhouse downstream of the turbines were very low. The tentative annual carbon balance calculation indicates that this reservoir was a carbon source with an annual carbon export (atmosphere+downstream river) of about 2.2±1.0 GgC yr(-1). The Nam Ngum Reservoir was impounded in 1971 without any significant biomass removal. Diffusive and degassing CO2 and CH4 fluxes were lower than for other tropical reservoirs. Particularly, CO2 diffusive fluxes were always negative with values ranging from -21.2 (April 2009) to -2.7 mmol m(-2) d(-1) (January 2010). CH4 diffusive flux ranged from 0.1 (October 2009) to 0.6 mmol m(-2) d(-1) (April 2009) and no degassing downstream of the turbines was measured. As a consequence of these low values, the reservoir was a carbon sink with an estimated annual uptake of - 53±35 GgC yr(-1).
2009-2010 年，在东南亚亚热带的两个水库——Nam Ngum 水库和 Nam Leuk 水库（老挝），对二氧化碳和甲烷的总排放量（从水库中排放和扩散）以及碳平衡进行了评估。这两个水库处于同一气候区，但主要在年龄、大小、停留时间和初始生物量库存方面存在差异。Nam Leuk 水库于 1999 年在部分植被清理和焚烧后蓄水。然而，蓄水 10 年后温室气体排放仍很显著。CH4 扩散通量范围为 0.8（2010 年 1 月）至 11.9 mmol m(-2) d(-1)（2009 年 4 月），CO2 扩散通量范围为-10.6（2009 年 10 月）至 38.2 mmol m(-2) d(-1)（2009 年 4 月）。这些值与其他热带水库相当。此外，水轮机下游发电站出水口的排放通量非常低。初步的年度碳平衡计算表明，该水库是一个碳源，每年向大气和下游河流输送约 2.2±1.0 GgC yr(-1)的碳。Nam Ngum 水库于 1971 年蓄水，没有进行任何大规模的生物量清除。扩散和排放的 CO2 和 CH4 通量低于其他热带水库。特别是，CO2 扩散通量一直为负值，范围从-21.2（2009 年 4 月）到-2.7 mmol m(-2) d(-1)（2010 年 1 月）。CH4 扩散通量范围为 0.1（2009 年 10 月）至 0.6 mmol m(-2) d(-1)（2009 年 4 月），并且在水轮机下游没有测量到排放。由于这些低值，水库是一个碳汇，估计每年吸收-53±35 GgC yr(-1)的碳。
