Why Is This Lake PINK?

what do ancient egyptian mummies your average carrot flamingos and these canyons on mars all have in common well they all help me answer what i thought was a pretty simple question why is this lake pink okay okay let me back up so in my last video i spent a lot of time looking around east africa and a significant amount of that was spent specifically looking at mount kilimanjaro but after a while my eyes started to be drawn to something else something in the background you can even spot it in the video right here taking a closer look and sure enough among the greens and browns of the earth it's a patch of pink not that far to the northwest of africa's tallest mountains what appears to be a lake immediately i was curious here we have a seemingly natural body of water and a pretty big one at that i mean come on you can see it from space shining a completely otherworldly color can you really blame me for asking questions what i found was that behind this intriguingly colored lake was a uniquely complex system that pushes life to its very limits and gives us a glimpse into what other unearthly or even alien environments might look like okay so my first step in getting to the bottom of this pink lake was to simply figure out what the lake's name was yeah big surprise right i don't actually know the name of every single lake on earth wow how dare i call myself an atlas pro but over my time of pretending to be one i've found the easiest way to figure out what some strange miscellaneous feature on the planet's surface is called is to go to google earth doing this i found well i surely found a lake to the northwest of kilimanjaro but here the color isn't quite the same i mean there's a little pink in there but honestly that could just be a mistake of the satellite image at first this made me a little worried but as it turns out this is actually our first clue following a hunch the next thing i decided to look at was well google earth again but this time i wanted to use their time lapse tool starting the earliest we can in 1984 at this time we can see the lake was pretty much pink and stays more or less the same until 2001 where we can see the lake grows much bigger and loses its color reverting back to the typical dark blue of lake water the very next year though the pink returns stays a little but by 2007 it's almost gone again the same happens in 2010 2013 2016 2018 and even 2020 this switching back and forth was exactly what i was looking for and by this point i thought i knew what was happening but okay you're right i might be getting a little ahead of myself google earth also gave me a name lake natron and now i really had all i needed to get to the bottom of this you see natron has a very old meaning one that traces from english to spanish as natron to the latin natrium to the greek nitron and finally back to africa for its language of origin the ancient egyptian natron where it's used as a place name in the wadi el natrun or the valley of natron checking back to google earth we'll find this valley features some lakes of its own except well these don't look anything like lake natron but just wait a second let's use google time lapse again but this time going back in time doing this we can see that well despite the crazy amount of development that's gone on here in recent years if we go back far enough these lakes also start showing us a pinkish reddish color which is a pretty good sign and means i'm onto something considering both of these places have what's essentially the same name lake natron and natron valley i think the next step is to look deeper into the term natron researching the history of these red egyptian lakes revealed that this valley once served a very important role in egyptian life here a substance unsurprisingly known as natron was mined from the lake shores producing a hard but brittle white crystal these weren't any ordinary rocks however these ones had special properties ones that made them incredibly valuable in ancient times when scrubbed against surfaces in the home they'd become clean brushing your mouth with it made your teeth last longer when put on a wound it would recover faster and perhaps most importantly when put on food it would dry it out allowing it to be preserved and it was this function as a preservative that earned natron a double-fold purpose in ancient egyptian society of course the preservation of food before the time of refrigerators and airtight plastic containers would have already made natron an immensely valuable substance but if it could preserve meat then it could also preserve human flesh making nature a key ingredient in the process of mummification this made not only this substance but by extension these lakes in wadi natron incredibly valuable to ancient egyptians both economically as well as religiously but what actually is natron well if you haven't already figured it out we only need to look at the periodic table for a real answer here we'll find natron is actually its very own element in a or an atrium okay okay now i know you might be thinking huh that's weird i've never heard of the element natrium before but well yeah you have the kind of natron found in these pink lakes actually consists of four different compounds bonded to a carbonate molecule this formed what we'd today call soda ash bonded to a bicarbonate molecule produces what's now known as baking soda bonded to a sulfate makes what's known as sulfate of soda are you starting to notice a pattern here because basically everything containing nitrium formed some kind of soda over time the term natrium was replaced with the name we used today sodium which brings us to the fourth compound common in natron sodium chloride or what today we'd call table salt altogether the big takeaway here is that both of the lakes in this egyptian valley as well as here in east africa contain exceedingly high concentrations of dissolved salts and sodas the next question we need to answer then is why is lake natron so salty and this is where our time lapse comes back into the picture if you'll remember we saw that over the years the lake switched back and forth from being a regular dark blue to being a dull pink and what this is actually showing us is the water level of the lake regularly fluctuating between being full and drying up this happens as the rainy season comes depositing large quantities of water to east africa filling the lake but then gradually the rain stops the dry season starts and the water evaporates away evaporation can lower the surface of a lake six or eight feet within a few months every time this happens the water that flows into the lake picks up trace amounts of salts residing in the soil and brings them along for the ride into this basin when a raindrop strikes the earth it either runs off into pools or surface streams or it sinks into the ground [Music] the water that gets deep into the ground stores up as a subterranean treasure sometimes moving out like an unseen river to surface as a spring feed a stream and run to the sea well the amount of salt brought into the lake on any given year is rather low as this cycle of rain and drought repeats itself over hundreds thousands i don't know probably millions of years these salts and sodas gradually build up and today lake natron is saltier than ocean water even when full this is the cycle of water by which all life survives the cycle which we tap by different methods according to our location but ocean water isn't pink and so neither is this lake when this is the case from our time lapse we can see the lake only gets pink when the dry season comes around and most of the water evaporates away while all of the salts remain turning whatever water is left hypersaline or in other words really freaking salty but okay okay i know soda ash baking soda and table salt are all white or even colorless and so no matter how much you put in water the color doesn't change at all which means we still haven't answered our question but now that we know lake natron is full of well natron we can start to ask how this collection of salts and sodas might affect the local biology think back to those ancient egyptians for a second who used natron both for cleaning and preservation what do those two things have in common that's right they're about killing bacteria or really any microscopic life that's what kept their teeth clean and prevented their mummies from simply decomposing how this works is a little complicated but trust me we'll get through it if you were ever in any sort of biology class you might remember the term osmosis or the process of chemicals traveling from areas of high concentration to areas of low concentration like water moving from not so salty areas to very salty areas until equilibrium is reached normally microbes take advantage of this by maintaining a higher body salinity than the water they occupy providing an inward flow of water without the organism needing to expend energy but when salinity skyrockets like in lake natron the water becomes far saltier than the body of the bacteria and instead of water moving into it it's actually forced out of their cell membranes and we all know how important water is to life and so without the ability to intake water most microbial life simply dies out or at least goes dormant until the rains return but okay think about that for a second with all the microbial life either dead or dormant there's going to be an over abundance of resources in the environment things like dissolved oxygen available organic matter and access to sunlight are now free for the taking and what's become an essentially non-competitive arena all a microbe needs to do in order to gain access to virtually unlimited resources is to be able to survive the hypersaline conditions of the lake water this offer of boundless food space and energy proved so tempting that not one but two different microbes the algae dunaliella selena and the archaea halobacterium salinarum developed the ability to over produce glycerol in their bodies which effectively act as a salt reversing osmotic pressure and allowing them to once again passively draw water into their bodies this adaptation granted these two microbes a salt tolerance greater than virtually any other organism on the planet gaining them exclusive access to all the resources the lake has to offer however this drastic change from a diverse microbial community consisting of possibly millions of different species down to a community of just two comes with problems of its own the biggest of these problems is the sun you see in a normal sample of lake water microscopic diversity abounds and you end up with an incredibly dense population of microorganisms all sitting on top of one another while this might not sound ideal this is actually what most microbes are used to an easy way to tell just how densely populated any given body of water is is by looking at how clear it is nutrient poor waters like those found in the tropics tend to have far fewer microscopic organisms making the water much clearer while nutrient-rich waters like those found in the arctic are absolutely chock-full of microbes making it far less transparent in lake natron however you have two contradicting conditions on one side you have absolutely no microbes but on the other you have a crap ton of nutrients this means whatever microbes do spec into surviving in an environment like this are now going to be receiving way more sunlight than they ever needed to be used to while this might sound like a good thing for what are in fact photosynthetic organisms we can't forget that overexposure to the sun is always damaging and so facing the brunt force of the sun with no other bacteria to hide behind these two microbes needed to adapt not only to the extreme saltiness of the lake but also the damaging amount of solar radiation bearing down on them from above what these microbes did to protect themselves from the full force of the sun is well exactly what i do when i get too much sun turn really really pink of course i do this by getting sunburned but this algae and archaea accomplish this by coating their bodies in pigments or in other words compounds that specialize in absorbing certain wavelengths of light duna lyella selena coats its exterior in a pigment known as beta carotene which yeah is the same reddish orange pigment stored up in the bodies of carrots that give them their characteristic color that's why if you look at donaliella selena under a microscope you can very clearly see this pigment in effect turning their bodies the same orange color as your typical carrot halobacterium salinerum on the other hand uses the pigment bacterial rubrin which makes their bodies take on a more reddish purple color despite being different hues these additional pigments serve the same function rejecting at least some of the sun's rays so now that these microbes are both highly resilient to excessive salt concentrations and damaging degrees of sunshine they're free to live and reproduce in the waters of lake natron gaining them access to all the resources it has to offer causing them to explode in population occupying every drop of the lake water it's this over abundance of just these two colorful microbes mixed together that produces the lake's peculiar color the orange of donaliella and the purple of halobacterium apparently adding up and averaging out to the pink you're seeing now and this is where things get interesting at least from an ecological perspective as once you have just one or two forms of microbial life you have the foundations for an ecosystem and so despite the harsh chemistry of the lake these pink microbes manage to support populations of equally pink filter feeders like briny shrimp which in turn support even larger animals like you guessed it flamingos in fact lake natron is the only breeding ground for the lesser flamingo a species that ranges across africa and even parts of india africa is a land of vast plains like the serengeti and africa is a land of delicate beauty with graceful creatures like the flamingos now when i first learned this i thought this was a little strange as most birds prefer to consume higher order foods like the seeds of a tree and rarely ever eat microbes but it would appear that flamingos buck this trend instead choosing to filter feed by plunging their heads into the water upside down and essentially drinking up the pink microbes as well as the pink briny shrimp and it's this reliance on these more basic food sources that brings these pigments into the digestive tracts and ultimately the bodies of flamingos giving the birds their distinctive color so there you have it this lake is pink because over millions and millions of years these salts in the earth have drained from the soil into its basin turning the resulting lake into a salt lake and depending on the season a hypersaline lake to the point where the only microbes that can survive are extremophiles which coat their bodies in pigments to protect themselves from the sun's rays these pigments in turn make the lake as well as the few members of its animal community pink but hang on if the natural cycles of a lake eventually turn them salty then why don't all lakes eventually become pink or pinkify if you will well so far we've seen how the specific geology of an area has forced the local biology to adapt altogether producing a unique ecology which if my banner is to be trusted means that there's just one last tenet of earth science that's unaccounted for in my explanation everyone's favorite geography and this is what sets lake natron apart from all the others first if we take an up-close look at the setting lake natron finds itself within we'll see its basin occupies a position literally within africa's great rift valley here the somali plate is pulling away from the african plate which given a few million more years will result in two distinct land masses separated by a new sea for the time being however these diverging plates have only produced a massive valley system stretching straight through the continent a side view of this valley would look something like this where we can see the african plate and somalian plate sitting high above the valley floor trapping any water that enters this has produced a series of endoraic basins where water can flow into but not out of lake natron's position within this valley makes it impossible for salts deposited here to ever leave unlike most other lakes where water flowing out carries excess salts with them besides this the floor of the rift valley is also relatively flat which means most of lake natron is actually quite shallow that's why high resolution images of the lake during the dry season show the lake split into two different parts there are the parts that remain dark blue these are the deepest pockets in the lake and then there's the rest of the basin which either dries up completely or maintains just a very thin layer of water and it's this shallow water where salt levels skyrocket and reddish pink colors take over you see this shallowness means the lake has a very high surface area to volume ratio and more surface area means more space for sunlight to hit and cause more water to evaporate contributing to what makes this lake so so so salty but if we zoom out a little further we'll also find more global scale factors at play here for starters lake natron's position almost exactly on the equator again increases its exposure to the sun driving those evaporation rates through the roof on top of this despite sitting at the same latitude as the congo rainforest only a few hundred miles away lake natron occupies a far more arid corner of africa where rains aren't nearly as plintable and come only seasonally altogether the local and global positioning of this lake make for the perfect combination of factors to kick-start the geologic biologic and ecological processes that result in a pink lake and this is where i got really excited because if all it takes for a lake to pinkify is high temperatures low precipitation and maybe some lucky geography then surely there must be other places around the world with similar conditions and yeah of course there is i mean we already saw these lakes in egypt experiencing the same discoloration which again can be found in a place that's really hot really arid and lacks outflow channels there's also lake redpa in senegal which receives salt not only through water straining into it but also from ocean spray blowing salt waters directly over it even if we go back to lake natron we'll find another smaller pink lake to the north lake magati though if we zoom in we'll find that much of the pinkest areas are actually man-made evaporation pools which they use to extract salts from the lake water and that's just in africa if we look to europe we'll find the salinas de torre vieja in spain which stay pink all year round while in asia there's iran's lake hermia which only occasionally turns red in the americas there's laguna colorada in bolivia which okay i guess is a little more orange than it is pink but all that means is that there's probably a greater ratio of dunliella found here but perhaps the best continent for pink lakes would be australia where we can find hutt lagoon hillier lake lake lashiel and qua raiding lake and trust me there are a lot more so be sure to tell me what other pink flakes i missed in the comments ultimately what these pink lakes show us is that despite their hyper saline conditions life is more than capable of thriving in extreme environments in fact these incredibly rare lakes serve as a lesson on just how resilient life can truly be which has implications beyond our own planet take mars for example a world teetering on the brink of liquid water at lower latitudes the water vapor condenses to form clouds that ride high in the atmosphere or swirl around the slopes of martian volcanoes and further south in the canyons and valleys there is frequently an ice haze seen to form and evaporate in the early hours of the morning as the sun warms the atmosphere we've already observed its slopes running with brine during its warm season and it isn't too hard to imagine that somewhere maybe even in just a single inconspicuous gully these primordial waters could form a spontaneous pool this oblique truncating of one set of terraces by another indicates that the climate turns on and off the first geological evidence for cyclical climatic change on a planet other than the earth now maybe a temperature event like this only happens once every 100 years or every 500 or thousand or even a million years but no matter the frequency this flood and drought cycle would nonetheless lead to the buildup of salts in basins across mars just as it does here on earth and so chemically speaking the closest analog we have for these earliest potential puddles of mars are our own pink licks which also just barely managed to win the fight against evaporation because of mars low atmospheric pressure and low temperatures water can't exist in liquid form [Music] it must either freeze or evaporate and if life can continue to persist and even thrive here there's hope that some form of life however primitive however radical however extreme some form of life could be able to call mars home [Music] the speculations about changes in the atmosphere and climate were closely related to the notion that life in some form might exist on mars hey everyone i hope you all had fun learning about pink lakes with me today this idea came to me really fast and i just knew i had to make this video as it's not often i get an idea that checks off all the atlas pro boxes so neatly so if you want to help support me and the channel there's a link on screen that'll take you over to my patreon other than that come on and subscribe already don't you want to be able to say you were here before 1 million uh also give the video a like if you hope this video does well against the cruel algorithm and make sure to send me pictures of even more crazy lakes over on twitter thanks some of africa's birds are so large you can feed a family of 10 from a single ostrich egg you

Channel: Atlas Pro

Views: 240,477

Keywords: education, geography, science, atlaspro, geology, biology, ecology, bacteria, molecular, algae, red, pink, shrimp, mars, flamingo, africa, kenya, tanzania, kilimanjaro, egypt, mummy, natron, lake, pond, bloom, osmosis, australia, hutt, lagoon, salinar, salt, baking, soda, sodium, natrium, element, periodic, table, sulfur, water, liquid, sun, photosynthesis, hillier, carrot, ancient

Id: 2kmb1ARg9m0

Length: 24min 10sec (1450 seconds)

Published: Mon Oct 18 2021