| Autor: |
Deshmukh, Chandrashekhar, Guérin, Frédéric, Vongkhamsao, Axay, Pighini, Sylvie, Oudone, Phetdala, Sopraseuth, Saysoulinthone, Godon, Arnaud, Rode, Wanidaporn, Guédant, Pierre, Oliva, Priscia, Audry, Stéphane, Zouiten, Cyril, Galy-Lacaux, Corinne, Robain, Henri, Ribolzi, Olivier, Kansal, Arun, Chanudet, Vincent, Descloux, Stéphane, Serça, Dominique |
| Předmět: |
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| Zdroj: |
Biogeosciences Discussions; 2017, p1-40, 40p |
| Abstrakt: |
Freshwater reservoirs are a significant source of CO2 to the atmosphere. CO2 is known to be emitted at the reservoir surface by diffusion at the air-water interface and downstream of dams or powerhouses by degassing and along the river course. In this study, we quantified total CO2 emissions from the Nam Theun 2 Reservoir in the Mekong River watershed. The study started in May 2009, less than a year after flooding and just a few months after the maximum level was first reached and lasted until end of 2013. We tested the hypothesis that soils from the drawdown area would be a significant contributor to the total CO2 emissions. Total inorganic carbon, dissolved and particulate organic carbon and CO2 concentrations were measured in four rivers of the Nam Theun watershed at nine stations in the reservoir (vertical profiles) and at 16 stations downstream of the monomictic reservoir on a weekly to monthly basis. CO2 bubbling was estimated during five field campaigns between 2009 and 2011 and on a weekly monitoring, covering water depths ranging from 0.4 to 16 m and various types of flooded ecosystems in 2012-2013. Three field campaigns in 2010, 2011 and 2013 were dedicated to the soils description in 21 plots and the quantification of soil CO2 emissions from the drawdown area. On this basis, we calculated total CO2 emissions from the reservoir and carbon inputs from the tributaries. We confirm the importance of the flooded stock of organic matter as a source of C fuelling emissions and we show that the drawdown area contributes, depending on the year, from 50 % to 75 % of total annual gross emissions in this flat and shallow reservoir. This overlooked pathway in terms of gross emissions would require an in-depth evaluation for the soil OM and vegetation dynamics to evaluate the actual contribution of this area in terms of net modification of gas exchange in the footprint of the reservoir, and how it could evolve in the future. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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