We’ve all seen the disaster films. “Armageddon”
taught us that all we need is Bruce Willis and a rag tag team of oil riggers to
save us from a meteor-related extinction. “The Core” showed us what happened if
our planet stopped spinning, (and we learned a valuable lesson about not
playing with Earthquake machines.) Other films like “The Day After Tomorrow”
depict a frozen wasteland or “Waterworld” in which all the ice caps have melted
and we’re completely submerged (epic foreshadowing Congress…)
But what happens when lakes start killing
people?
While it’s probably not going to make a
blockbuster appearance at the box office any time soon, the reality of Limnic
Eruptions, also referred to as Lake Overturn, is a very real, and very deadly
one. So how do lakes go about killing people? I’ll give you a hint, it’s not
because people drown in them, and it isn’t disease hiding in the water. Turns
out, there’s something even more deadly lurking deep down below.
Today at TI&IT we’re going to talk about
Lake Overturn, and two natural disasters in the early and mid-1980s that gave
us great insight into this destructive phenomenon. We’ll also talk about one lake
that, if it were to explode, would kill over 2.2 million people in process and the
procedure for eliminating this issue. We’ll also briefly touch on some of the
other locations where we can find similar situations throughout the world.
But first, let’s talk about where this
indiscriminate killer has already left his mark. And to do that, we need to
travel to Africa. Specifically, Cameroon, to a small lake called Monoun. This
is where the noxious assailant first made his appearance, in the form of an
innocuous, little white cloud.
That Ain’t Casper
See that mass of white accumulated at the
bottom of the lake in the photo above? No, that isn’t from some factories
smokestack. It also isn’t a reflection of light off the lake. It’s something
far more sinister.
No…it’s not Casper the Friendly Ghost either…
It’s a noxious gas; well, maybe not as toxic as you might think. We actually
expel it every time we draw in a fresh breath.
It’s carbon dioxide.
But in 1984, in Cameroon, that little white
cloud was responsible for the death of 38 people bordering the lake. How did
this happen you ask? Well, we may exhale Carbon Dioxide, but that’s just the
thing, we get rid of it. When exposed to it in massive quantities, Carbon
Dioxide can completely displace the air due to its heavier density, effectively
choking out the oxygen in the environment around us. In 1984, that’s exactly
what happened. While the villagers slept, the Co2 sunk over the ridges of the
mountains above and moved slowly through the village, displacing the air and
asphyxiating everyone.
But this was just a shadow of the dangers to
come. Two years later in 1986, a similar event not far away would dwarf the
tragedy of Lake Monoun in every way imaginable. On August 21st, Lake
Nyos spewed a gigantic cloud of gas upward from its depths. The cloud crept
over the villages surrounding the lake while the people slept. By morning,
roughly 1,800 people were dead, stifled of air in their sleep. Livestock lay
dead all over the roads and the countryside.
Fear and panic swept through the area.
Everything from chemical attacks to angry Gods was thrown out as a possibility
for the mysterious deaths occurring around the lakes. Villagers had reported
seeing the white cloud moving across the lakes. In the aftermath of the Nyos
tragedy there were only six survivors, and they had suffered peculiar “burns”
all over their bodies. These lesions were highly inconsistent with anything
people had seen before.
These “burns” would only make sense if the
Co2 had been superheated, but seeing as the corpses of the other victims showed
no signs of scalding trauma this theory held little weight. It would take a
team of brilliant researchers, and a radical new theory, to explain the
tragedies at Nyos and Monoun.
Good thing the world had both of those up its
sleeve.
Nyos’ Secret Volcano
Lair
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After the incident at Monoun a group of
researchers led by Scientist J.C. Sabroux took to the waters to find out just
what had occurred. They paddled out the center of its surprisingly calm waters
and began lowering their equipment in. Basically the tools used were tubes with
openings used to gather samples from the deepest sections of the lake, but as
they drew the tubes to the surface something strange was happening, gas bubbles
were rising up ahead of the equipment, making the surface look like the surface
of a carbonated beverage.
The bottom of the lake was filled with Co2,
this didn’t make any sense to the researchers until they realized something. They
were sitting on a volcano. Volcanoes are well known for their violent history
of erupting various hot gases into the atmosphere, chief amongst them being
Sulphur and Carbon Dioxide.
Just because the volcano doesn’t have any
active plans to decimate the village below doesn’t mean it doesn’t have to let
off some steam. Through underground vents called Chimneys, the volcano sends
the gas upward to the surface where it mixes with ground water. As the ground
water mixes with the lake water the gas is intermixed as well and sinks to the
bottom. The Chimneys also directly feed the lake from below as well and the
high pressures of the great depths keep it trapped at the bottom.
Until an Earthquake does something like
causes a rock slide to send tons of heavy and dense material crashing down to
the depths. As we all know from freshman year Earth Science class, when we drop
dense materials into a glass of water it displaces it. And if you drop a rock
into something carbonated (like a Coca-Cola for instance) it causes the Co2 to
get riled up and rise to the top of the glass.
So when the rock slide sent those stones
crashing into the water and to the bottom, it stirred up the Carbon Dioxide.
Excited, it rose to the surface and formed a cloud, killing the villagers. The
ones it didn’t kill suffered burns consistent with overexposure to carbon
monoxide. What ended up happening was when the gas shut their bodies down it
stopped circulating blood to the skin first. As a result the skin cells began
to die and blistered up.
Now there are a lot of lakes that contain
gases throughout the world. What made Nyos and Monoun so special? Well they
were Meromictic Lakes, which means they were stratified, they didn’t intermix.
Allow me to explain this a bit further.
Most lakes throughout the world are Holomictic
or Polymictic. What this means is that through certain means these lakes stir
themselves up to re-oxygenate the water at deeper levels. Wind is a good
example of this, as it pushes along the surface of the water it stirs it up
aiding in current flows, this causes the lake to turn itself over, preventing
gas buildup.
Another method for lakes turning themselves
over is temperature shifts. Optimally at 4 degrees above freezing (32 degrees
F) the water on the top will sink to the bottom because it’s now heavier than
the much warmer water below. This is why during winter months fish tend to
school around the bottom of lakes, the water there is more oxygen rich. The
warmer water rises to the top to start the process over again.
Tropical lakes like Nyos and Monoun are calm
and warm year round and don’t receive the benefits of Polymictic lakes. As a
result, dangerous gas buildups can occur. In 1987, Sabroux and his team
announced their findings to the world, coining for the first time, the term “Lake
Overturn.”
So now that they knew what the problem was,
how the heck do they fix it?
Degassing: Like
Xantac For Lakes!
A lake of Monoun’s size only needs one or two
of these pipes to not only keep it at safe levels but within a course of five
years, almost completely eliminate the gas. Nyos will cost more money however
being that it’s much larger and requires six to eight pipes to accomplish the
same feat.
But what about the deadly giant Lake Kivu
near Rwanda?
Kivu is roughly 2,000 times the size of Nyos
and should it decide to go through a Limnic Eruption (Lake Overturn) it would
take the bordering population (around 2.2 million people) with it. And there’s
an even bigger problem still. Lake Kivu is host to an even deadlier monster at
its depths.
Just above the layer of Carbon Dioxide at the
bottom is another gas, Methane. Those of you familiar with chemistry know that
Methane creates an even bigger problem than Co2, because unlike Carbon Dioxide,
Methane is explosive. It’s a fossil fuel; in fact, Bralirwa Brewery in Rwanda
along Lake Kivu has been using this naturally occurring fuel to fire its
equipment since 1963.
Unfortunately, while this is genius, it doesn’t
chip away at the methane content fast enough to bring it down to safe levels.
International efforts are underway to fund a project which will harvest the
methane from the lake to be used as a fuel source. Venting the Co2 will undergo
a process like Nyos and Monoun, but Kivu will be far more costly because of its
size.
Whatever they choose to do and however they
choose to do it, it needs to be done soon. In the early 2000’s a volcano
bordering Kivu erupted sending molten magma pouring into the lake. Had the lava
reached the layer containing the methane it’s likely a highly explosive
reaction would have occurred and the entire population along the lake would
have been killed. Case in point:
Still don’t believe me? Fine, don’t take my
word for it. But you should certainly listen to the distinguished Professor
Robert Hecky. When he was working for the University of Michigan in the United
States he had core samples drilled from the deepest parts of the lake and his
findings were disturbing. It turns out every 5,000 years or so the gas buildup
gets so great that a Limnic Eruption is inevitable, and we’re just about due.
The good news is that since the breaking of
this news, the scientific community and energy entrepreneurs worldwide have
been chipping in to get at the methane below the bio-line of Lake Kivu. With
any luck a violent eruption like the ones seen in the distant past won’t occur
in Rwanda again.
And that’s great news. Because personally, I
think they’ve had enough bad luck.
So…You Said There’s
More of These…?
I did, and they are located all over the world.
However, not all of them produce gas levels like Kivu, Nyos, and Monoun. As a
result, while they don’t turn over, they don’t pose a threat to the populations
in the surrounding areas. From Lake Vanda in Antarctica:
To Jellyfish Lake in
Palau on the Asian continent:
Even The Black Sea, bordering the countries
Russia, Romania, the Ukraine, Georgia, and Turkey is considered to be
Meromictic:
But don’t fret. If you live on the border of
any of these lakes or other Meromictic ones you needn’t worry. As I said above,
these don’t contain the gases necessary to provide the devastating effects Kivu
is capable of. If you want to see more Meromictic lakes check out the Wiki by
clicking here.
Thanks for reading everyone!
-
Ryan
Sanders
Thanks for reading
everyone! Hope you enjoyed the article today! If you want to read more about any
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