Scientists to detoxify Cameroonian killer lakes
An international team of scientists, technicians and engineers has begun work to detoxify two Cameroonian lakes, one of which killed over 1,700 people in 1986.
The team has arrived in the West African state with the aim of reducing carbon dioxide in Lakes Nyos and Monoun in the west of the country, near the Nigerian border to tolerable levels in three to five years. The work is essential as there is a renewed build-up of carbon dioxide in the depths of the two lakes, which are located on a seismic fault. In 1986, a tremendous explosion of CO2 from Lake Nyos, killed 1,746 people as well as livestock up to 25 km away. Two years earlier a similar explosion occurred at Lake Monoun, near Nyos, killing 34.
The explosions occur when dissolved CO2 seeps from springs beneath the lake and is trapped in deep water by the high hydrostatic pressure. When the CO2 saturation level is reached, the gas-rich water can be drawn up, for example by an earth tremor, triggering an explosive over-turn of the whole lake, and causing CO2 to flow over the ground surface, asphyxiating those caught in the gas cloud.
The Japanese, American and French experts are to carry out studies on ways to extract the accumulating carbon dioxide from the bowels of the lakes and siphon it into the atmosphere on a permanent basis and how to dispose of contaminated water, and will install a satellite remote control system to warn people of possible gas explosions. Since 1990, a French team has carried out a series of tests attempting to release the gas slowly through vertical pipes. One such 195-metre (640 foot) long polyethylene pipe produced a 30-metre (100 foot) jet.
The new detoxification process using 12 polyethylene pipes was developed by French volcano expert Michel Halbwachs of the University of Savoie and is called the “Nyos Organ”.
The two Cameroonian lakes, along with Lake Kivu, on the border between the Democratic Republic of Congo and Rwanda, are thought to be the only ones to accumulate carbon dioxide in the lower strata of their basins.