The 'Killer Lake' of Cameroon
Weisburd, Stefi, Science News
In the early morning hours of Aug. 16, 1984, a parish priest, a young man named Foubouh Jean and others were riding in a van past Lake Monoun in the Republic of Cameroon, when they noticed a man on the roadside who appeared to be asleep on his motorcycle. But when the priest drew near the motorcycle, he discovered that the man was dead. As he turned back toward the van, he, too, collapsed. Jean and a companion, smelling a strange odor like that of car battery fluid, realized the air was deadly and began to run away. Jean's companion soon succumbed, but Jean managed to escape to the nearby village of Njindoun.
By 10:30 a.m., authorities had found a total of 37 people lying lifeless on the road, apparent victims of a mysterious chemical cloud that had enveloped a 200-meter-long stretch of the road that morning. No autopsies were conducted, but Emmanuel M. Njock Bata, a physician who examined the bodies, concluded that the people who had been traveling to market in the open air before dawn had died of asphyxia. Bata, now at Tulane University Medical Center in New Orleans, told SCIENCE NEWS that mucus and blood had oozed as foam from the victims' noses and mouths, and their bodies were rigid from seizure. They also had first-degree chemical burns on their skin, though their clothes were unaffected.
The results of an investigation, now being made public, indicate that the cloud that killed the people was generated naturally in Lake Monoun. This is the first known incidence of such a lethal, natural cloud, say the investigators.
There were several signs on Aug. 16 that the lake was involved. When Bata and a police commandant first neared the area at 6:30 that morning, they saw the smokelike cloud coming from the direction of the lake. The cloud reportedly tasted bitter and made them nauseated, dizzy and weak, so they retreated until 10:30 a.m., when it had dissipated. Between the lake and road, animals, grasses and shrubs had been killed, and plants on the shore had been flattened. Njindoun villagers also reported hearing a loud explosion from the lake about 11:30 the night before. And on Aug. 17, authorities noted that Lake Monoun was reddish brown, indicating that the normally placid waters had been stirred up.
The government of Cameroon, which had at about that time put down an attempted coup, was worried that the incident might have had political overtones, so they kept the event quiet, according to volcanologist Haraldur Sigurdsson. With the help of the U.S. Agency for International Development, Cameroon invited Sigurdsson and Joseph Devine, both at the University of Rhode Island in Narragansett, to Africa to work with Cameroon volcanologist Felix Tchoua in a study of the lake. The researchers were to determine whether the cloud had been produced naturally or by humans -- whether, for example, chemicals or explosives had been dumped into the lake.
Sigurdsson's group could find no evidence of human wrongdoing. And now that the U.S. and Cameroon governments have granted permission to air the story, the researchers can divulge their theory of the "killer lake." William Evans, who along with Theresa Presser and Katherine Pringle at the U.S. Geological Survey in Menlo Park, Calif., conducted the chemical analyses for the study, will present the researchers' findings Dec. 13 in San Francisco at the fall meeting of the American Geophysical Union.
When he first arrived at the lake, Sigurdsson suspected that the cloud had been produced by an abrupt volcanic eruption, because Lake Monoun is one of many small volcanic crater lakes in the region. Volcanic gases might have rushed up through the lake, expanding into an asphyxiating cloud of carbon dioxide and other gases. …