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Africa

Toxic gas beneath DRC lake threatens millions

A deadly threat is lurking beneath DR Congo’s Lake Kivu. Rising carbon dioxide could affect millions of residents if engineers fail to stop the gas emission from reaching the water's surface.

Kazana Ragi fears for his village Nzulo. The fisherman and motorcycle taxi driver lives on the Gulf of Kabuno, in the northwest of Lake Kivu. The water is much shallower than the rest of the lake, the risk that carbon dioxide (CO2) escapes here is significantly greater than in the deeper parts.

Locals here are already facing the dangerous threat of the gas emissions. In 2008, it was buried 25 meters below the surface, now it is just 12 meters, said the Ministry of Energy and Water and the Volcanological Observatory at the nearby metropolis of Goma.

Fisherman Ragi believes that the gas is already affecting the livelihoods of people. "If you leave the fishing net long inside the water, the gas destroys it, and if you go into the lake, the skin becomes white. That scares me," the 28-year-old told DW.

Though such observations have not yet been scientifically proven, local residents are afraid of the carbon dioxide. If something happens and they can not explain it, they quickly put the blame on the gas.

Fishermen inside a wooden canoe as other men look on.

Residents in the Gulf of Kabuno are scared of Lake Kivu's carbon dioxide

Thomas d'Acquin Muhiti, president of the Civil Association of North Kivu province, understands the panic of his countrymen. Carbon dioxide is very dangerous. "In a short time it can come up and explode," said the civil rights activist.

CO2 is actually nontoxic to humans, but if taken in high concentrations it hinders the absorption of oxygen which could quickly lead to death. Apart from reaching the surrounding villages on the Gulf of Kabuno, a CO2 bubble would also affect the barracks of MONUSCO, the UN peace-keeping mission which is stationed in eastern DR Congo.

$3 million dollar project

The government of North Kivu province insists that no immediate danger exists. Nevertheless, people need to take preventative measures said the Minister of Energy and Water in Goma, Anselme Kitakya. The French company Limnological Engineering has now been contracted to remove the carbon dioxide from the Gulf of Kabuno with the help of a new technology. The Congolese government in Kinshasa has invested $3 million (2.6 million euros) in the project.

Engineers have already installed a platform 2 kilometers (1.2 miles) from shore. From there, a pipe extends to the depth of the sea where there is the highest concentration of carbon dioxide. With a special instrument, a gas-lift, you pull the water upward, explains Pierre Lebrun, project manager at Limnological Engineering. The gas is then separated from the water, says Lebrun. "The water is pumped back whereas the CO2 evaporates into the atmosphere."

Two men carry instruments to measure carbon dioxide levels in Lake Kivu, DRC.

Geochemist Mathieu Yalire (L) constantly monitors CO2 emissions around Lake Kivu

Initial tests have shown that the technique works, assured the manager. In June, the pilot project is to be turned into a permanent operation. If all goes as anticipated, three more plants would be installed by the end of the year. The pipes must remain in the lake for a long time since the two active volcanoes, Nyiragongo and Nyamulagira, are underground constantly spitting carbon dioxide in Lake Kivu.

In addition to carbon dioxide, Lake Kivu also emits methane. Rwanda, which lies on the other side of the lake, is already seeking to produce electricity from the gas. Kigali and Kinshasa plan to build a common methane power station which could in turn reduce the risk that carbon dioxide escapes. If the pressure on the two gases in the depth increases, the methane initially makes its way to the surface opening the gate for carbon dioxide to escape.

Trapping carbon dioxide

In the Gulf of Kabuno there is virtually no methane gas. It is all about reducing the carbon dioxide in the lake. But the engineers have to proceed with caution and not release too much carbon dioxide into the air at once. This could put humans, animals and the environment at risk since CO2 is a greenhouse gas that contributes to global warming.

The DRC government wants to plant 360 hectares of land with 560,000 eucalyptus trees. "Reforestation is part of the project on the Gulf of Kabuno" said Minister Kitakya. However, the trees will not be able to swallow all the gas, especially during the early stages.

Nyiragongo volcano in Goma, DRC.

Nyiragongo volcano continues to feed Lake Kivu with carbon dioxide underground

There is also the issue of the purified water from the depths. It is pumped back into the lake, but must not be mixed with the water above. The chemical nature of the water layers in Lake Kivu differs from one to another. Substances found in the deep sea would kill the fish in the bio-zone at the surface.

"It would be a disaster if the remaining water would be in the bio-zone. That would destroy the ecosystem. The fish and other animals may no longer exist," explained Mathieu Yalire, head of geochemical department at the Goma Volcanological Observatory. That would have enormous consequences for the people on the Gulf of Kabuno who depend on fishing the lake for their living. Fisherman Ragi has only one wish: That the dangerous gas would get out of the lake.

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