Table 2.

Chemical composition and concentration of CO2 (aqueous CO2+HCO3) in water samples from Lake Nyos

Depth (m)Temp (°C)pHEC (mS m−1)ORP (mV)NaKCaMgFe (mg l−1)ClSO4CO2Siderite Log(Q/K)
504.21.87.49.40.30.3
21.16.5614225.72.69.29.20.130.20.0392.08
100113.828370.40.3
22.655.3770172146.03136760.50.131080.92
150154.941550.50.4
23.35.2291243187.64350990.60.154390.76
1806072, 6292
197.547561080.60.26416
200175.545670.60.49108
24.95.13107260197.051641230.60.277360.60
204186.147690.90.49988, 9900
24.15.10109260187.354671200.60.282220.43
208
24.85.06115258218.562782170.70.191620.96
209226.753810.70.312 012
210
24.25.08141259219.663792680.70.111 5010.93
• Duplicate analyses were done for samples at depths of 180 and 204 m in this study. Italic denotes concentrations of Fe and other chemical compositions in lake water collected in March 2012. Saturation indices of siderite were calculated from these values. The upper chemical compositions at the same depth were also analysed in December 2011 and precipitation rates of siderite were measured.