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Carbon dioxide dynamics in lake Kivu during the dry and wet seasons

par Borges, Alberto Vieira;Delille, B.;Descy, Jean Pierre;Darchambeau, F.;Leporcq, B.;Servais, Pierre ;Lepoint, G.;Bouillon, Steven;Abril, G.
Référence European Geosciences Union General Assembly 2008(13-18 April 2008: Vienna, Austria), Geophysical Research Abstracts, Vol. 10, EGU2008-A-09685, 2008, Copernicus Publications, Vol. 10
Publication Publié, 2008

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Résumé :

Lakes are significant sources of CO2 to the atmosphere ranging between 0.14 à 0.17PgC yr-1 globally. This emission of CO2 is comparable to the one from rivers of 0.34PgC yr-1 and from estuaries of 0.32 PgC yr-1. Africans lakes are characterized bypartial pressures of CO2 (p CO2) twice higher than the global average (2300 ppmversus 1060 ppm). Also, African lakes represent about 10% of the total lake surfacearea (225,000 km2 versus 2426,000 km2). The emission of CO2 is attributed to thenet heterotrophy of these systems sustained by the organic carbon inputs from thewatershed. However, several unknowns remain on the CO2 dynamics in lakes, in particularAfrican ones : (1) few simultaneous and integrated studies of CO2 dynamicsand metabolic performance are available; (2) African lakes are under-sampled in relationto temperate and boreal lakes, (3) most pCO2 estimates in lakes are based onpH and alkalinity measurements with unkown quality, (4) seasonal and diurnal pCO2variations in lakes are significant but not well constrained, and (5) spatial variability ofpCO2 in lakes is strong but not well documented. Here we present preliminary resultson CO2 dynamics in surface waters of lake Kivu that was sampled in March 2007 andAugust 2007, in the frame of the Carbon and Nutrient cycles in lake Kivu (CAKI)project (http://www.co2.ulg.ac.be/kivu.htm).