Has anyone seen the show on Discovery/TLC/PBS (sorry, I haven’t seen it for a long time) about the area in Africa where Carbon Dioxide seeps out of the ground from geothermal activity and collects in low-lying areas (since it’s heavier than air). Freaky cool. They film a lizard walking down the hill into this bowl-shaped depression. It starts to gasp and generally stagger and freak out, before managing to wander back uphill and, luckily, out of the gas pocket. I think they also showed a bird that didn’t wise up in time. Especially unnerving was the fact that the corpses stayed extremely well-preserved.
I think I remember the show. It was about a lake in a volcanic crater in Cameroon. Carbon dioxide would build up in the depths of the lake until some disturbance would send it to the surface. I’m guessing it might have been on NOVA a few years back.
The July issue of Scientific American had an article about the lakes in Cameroon that “erupted” in the 1980s, releasing vast quantities of CO2 and killing hundreds.
Apparently the CO2 (as toadspittle correctly states, from local geothermal activity) accumlates in the lower layers of the lake until some critical mass is reached or some disturbance occurs and, unfortunately, once begun the release is self-sustaining.
The article interviews a rare survivor and discusses attempts to prevent the deadly buildups from occuring. Some of the techonological solutions appear promising and relatively inexpensive, but this is a very poor part of the world so it is sadly unlikely that they will be implemented.
FWIW, unlike nitrogen, high concentrations of carbon dioxide can be fatal even when adequate oxygen is present.
Finally, a funny family story: We live relatively close to Mt. Rainier which, though long quiet, could possibly erupt. Molten lava is not a threat but volcanic gases and lahars (the Mt. St. Helens-like hot ash flows) are. (There are towns built on the old lahar plains that have actual volcano drills where they evacuate school children to higher ground.) At any rate, Mrs. Pluto and I and the Plutinos were out for a drive one day and Mt. Rainier was dramatically dominating the skyline. The possibility of eruption came up (most of the Plutinos are boys, who think that kind of thing is way cool) and I was pontificating about the poisonous gases, etc. The boys were speculating about what kind of poison gases these might be when their sister, at the time about six years old, opined that she knew a kind of poison gas. Surprised, we asked her to explain. “Our farts!”, she said.
Right. In addition to the hapless wildlife dying on dry land, I think there was also a big part of the program devoted to a lake’s gas eruptions … possibly associated w/ poor (economically, as well as unlucky) locals who worked in the sulfur trade. I think they had to walk down to the lake’s edge and pick up enormous chunks of precipitated sulfur, then carry them back up. Researchers were trying to develop better forecasting methods to predict when the CO2 would erupt, since it often burst out and killed all the workers in the vicinity.
It seems to me that some sort of low-tech pump was installed in the lake that slowly vents off small amounts of CO2 all the time, so a big outburst doesn’t happen again.
There’s a travel book by Dervla Murphy, I think it’s called “With Eggbert in Cameroon” or something like that (Eggbert was her horse’s name), about her travels around Cameroon on horseback. She visits the area of those lakes that leak deadly gas and describes and discusses them well. Dervla is an old Irish lady and is the toughest woman in the world IMHO.