Cédric Morana

Natural lakes are thought to be globally important sources of greenhouse gases (CO 2 , CH 4 , and N 2 O) to the atmosphere although nearly no data have been previously reported from Africa. We collected CO 2 , CH 4 , and N 2 O data in 24 African lakes that accounted for 49% of total lacustrine surface area of the African continent and covered a wide range of morphology and productivity. The surface water concentrations of dissolved CO 2 were much lower than values attributed in current literature to tropical lakes and lower than in boreal systems because of a higher productivity. In contrast, surface water–dissolved CH 4 concentrations were generally higher than in boreal systems. The lowest CO 2 and the highest CH 4 concentrations were observed in the more shallow and productive lakes. Emissions of CO 2 may likely have been substantially overestimated by a factor between 9 and 18 in African lakes and between 6 and 26 in pan-tropical lakes.