How do Dangerous Unstable Lakes pose a potential threat to human populations?

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The African continent features deep lakes with stable, dense lower layers that often do not mix with the upper layers, primarily due to higher salinity. This stability can be disrupted by disturbances such as volcanic activity or underwater landslides, potentially leading to the release of dissolved gases like CO2 or methane. If these gases bubble out of solution, they can create a cycle that draws more water from the depths, exacerbating the release of gas. Such events pose significant risks, including the potential for large-scale CO2 releases that could suffocate nearby populations. Simple technologies, like airlift tubes, can be employed to safely reduce dissolved CO2 levels in these lakes. Each lake has unique chemical properties that affect its behavior. Historical instances of gas release have been documented, highlighting the dangers associated with these phenomena.
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The African continent has several deep lakes with a deeper layer that is mostly not mixing with the overlaying layer. This could be due to a higher salinity, making the deeper layer more dense, and therefore stable.
If enough CO2 or methane is pumped into the lower layer of water, it may get close to its saturation point. Nevertheless this can be stable for long times.
However, if something disturbs the deep layer. Part of it may slosh around and moving some of it to a shallower area with less pressure. If gas starts bubbling out of solution, the water becomes less dense volume of water and rises toward. This will draw water from lower regions up under neath to where it will release gas and continue the cycle.

The initial disturbance could be any of a number of things: volcanic heating of deep layers, underwater land slide (maybe from an earthquake) disturbing enough of the deep layer to start the cycle. ?

Water can hold huge amounts of CO2, so really massive amounts can be released, enough to flood a valley with heavier than air CO2 and suffocating them.
This is known to have at least once, and is a potential threat to at least hundreds of thousands.

Using very simple technology, any aquarium hobbyist would be familiar with, an airlift tube, a self powered (once started) pump (the air lift tube), is used to pump saturated water from the bottom of one of these lakes.
The rate is easily controlled with a valve. Amount of dissolved CO2 levels were reduced safely.

Different lakes work differently because they have different chemistries going on. Different solutions.

Much of this and a lot more is in this nice Nature podcast written up as a little article.
Maybe the writer went to a meeting.
 
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I’ve seen something of this on NOVA where heavy gases would get released and stream down a mountain and inundating villages or laying low in a depression until a small animal or child ventures in and can’t breathe.

There was one project that pumped out the trapped methane from a deep lake to prevent the buildup but I can’t remember where in Africa.

https://www.forbes.com/sites/davidb...angerous-volcanic-phenomenon/?sh=55f92fb1247b
 
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Heres the NOVA link

 
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