19 August 2017

Solar evaporation ponds


I was flying into Salt Lake City last week and noticed an interesting landscape (photo above).  After returning home I searched Google Maps and saw that this area was identified as "Compass Minerals":

"At our Ogden, Utah, location at the Great Salt Lake, we draw highly saline waters from the lake’s most remote areas into very shallow solar evaporation ponds to produce salt, sulfate of potash (SOP) and magnesium chloride."
I wonder if the coloration is the result of minerals alone, or whether the ecology of the ponds supports some type of microbial or algal flora.  Anyone know?  [see the comments]

Addendum:  Salt ponds in San Francisco Bay

via

16 comments:

  1. This would be a brine operation, where water's pumped into an area with that mineral, then pumped out and the water evaporated, so the color's coming from something else in that area. Salt, potash, and mag are usually white or grey. I'd be surprised if anything bacterial could survive in there - it would be like the Dead Sea times a thousand.

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    1. I think some of the African wetlands where flamingoes get their color from algae are hypersaline.

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    2. It's possible, though I'd think Compass would want to control growth in their product - dead algae would make their produce stink when they bag it or sell it.

      I've worked at a salt mine for years and have yet to see anything grow in the exposed puddles or brine ponds. But that's a based-on-personal-experience answer, not a scientific one.

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  2. It's probably archaea. That's the domain of organisms that gives the hot springs in Yellowstone their color and they're able to live in much more extreme environments than bacteria. I know they're what makes the halite from Trona, CA pink.

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  3. The reddish color is often from Halobacteria -- extremophile archaea that have bacteriorhodopsin that gives them the red color. Another culprit is Dunaliella salina, a green alga that also has reddish coloring thanks to some carotenoids. There are also quite a few cyanobacteria that make a good living in salt ponds. I don't know of any microbial studies in those Utah ponds in particular, but we know a lot about these types of microbes from the San Francisco Bay and the Guerrero Negro salt ponds.

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  4. Please riddle me this: a friend won't eat Sea Salt because there is plastic in it. Could this be true? I've seen beach sand magnified /microscopic and it looks like another world.

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    1. There is no salt in sea salt as the crystallisation process excretes impurities as the crystals form. Telling people there is plastic in sea salt is, however, a great way to market Himalayan rock salt.

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    2. typo alert: "There is no plastic in sea salt..."

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    3. Ah yes, thank you. I should clarify that there certainly is salt in sea salt.

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    4. It turns out I was wrong: https://www.theguardian.com/environment/2017/sep/08/sea-salt-around-world-contaminated-by-plastic-studies

      It's also in most of the world's water supplies: https://www.theguardian.com/environment/2017/sep/06/plastic-fibres-found-tap-water-around-world-study-reveals

      This is indicative, however that plastic is _everywhere_ and not eating sea salt is not going to make much of a difference.

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  5. I received the following comment in an email from a family member:

    "I will do a bit more checking of literature but here is what I know now: The salt in these ponds is quite different than sodium chloride so extremophilic archaea such as Halobacterium halobium are probably not the dominants as they need very high NaCl, at least 5x sea salt ( by memory). These ponds will also be alkaline and have more in common with African soda lakes. A variety of photoheterotrophic and photoautotrophic bacteria (typically purple in color) tolerate pH in the 8 to 10 range which seems about right based on chemistry, but not certain of their salt tolerance. I assume that the green ponds are less concentrated in salts and are dominated by eukaryotic algae. Again will check. I found some fabulous airplane shots of bright blue evaporation ponds that have little relationship to biology and will send also."

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  6. https://en.wikipedia.org/wiki/Salt_evaporation_pond#Algae_and_colour_of_evaporation_ponds

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    1. Thank you, Guillaume for that link. I've appended an additional photo to the post and now have a topic to harvest for the photos in the next divertimento.

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  7. There is a particularly impressive example in the desert in Xinjiang, China, near the former bed of Lop Nur: https://goo.gl/maps/uFwv5Yvyx5s. That particular one is a potash facility, I believe. Of interest are the canals you can see branching off from the north edge.

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