• Citer

Carbon cycling in the mixolimnion of Lake Kivu (East Africa)

par Borges, Alberto Vieira;Descy, Jean Pierre;Delille, B.;Lepoint, P.;Servais, Pierre ;Abril, G.;Bouillon, Steven;Schmid, Roland Michael;Pasche, N.;Darchambeau, F.
Référence 6th European Geosciences Union - General Assembly 2009(19 – 24 April 2009: Vienna, Austria), Geophysical Research Abstracts, Vol. 11, EGU2009-10832, 2009, Copernicus Publications, Vol. 11
Publication Publié, 2009

Publication dans des actes

• Détails
• Contenu

Résumé :

Lake Kivu is situated in the Western Rift Valley, and has unique limnological characteristics, as temperature andsalinity increase with depth, due to bottom geothermal inputs. Due to its permanent meromictic nature, CO2concentrations are extremely high in Lake Kivu’s bottom waters, similar to other “killer lakes” such lake Nyos inCameroon.We obtained a data-set of inorganic carbon (pCO2, pH, TA, DIC, DIC stable isotopes), CH4, inorganicnutrients, organic carbon, bacterial production, and primary production in the mixolimnion of lake Kivu during therainy season (March 2007), the late dry season (September 2007) and the mid dry season (June 2008).We show thatthe surface waters of lake Kivu were a source of CO2 and CH4 to the atmosphere albeit that the mixolimnion wasnet autotrophic at the community level, based on DIC mass balance budgets, sediment trap data and measurementsof bacterial production and primary production. This rather unique situation is related to the important magmaticsources of CO2 in the bottom of the lake.