Abstract

The amount of dissolved CO₂ (CO_2aq) in Lake Nyos, Cameroon, has been measured annually since January 2011. First, concentration was estimated by a chemical analysis with the assumption of equilibria between CO_2aq, and . The estimated was correlated with the observed electrical conductivity of lake water. The profile of [CO_2aq] was generated from the electrical conductivity, pH and temperature profiles. The [CO_2aq] profile was integrated over the water column to obtain the total amount of CO_2aq. The amounts were 8.4, 6.8, 5.5, 4.4 and 3.9 Gmol (=10⁹ mol) in 2011, 2012, 2013, 2014 and 2015, respectively. The fast reduction between 2011 and 2013 was attributed to the installation of two additional degassing pipes in April 2011. However, the rate of reduction decreased between 2014 and 2015 due to the reduced [CO_2aq] at the inlet of the degassing pipes.