Hey Cryolist,
A bunch of people expressed interest in this topic, I wanted to send a round up back out to the list.
Lots of ideas about different surface tension, the role of sediment in the water, and ideas to try to recreate in the lab.
Happy hypothesizing!
Allen
Alex Michaud
Just saw your cryolist post and watched the video with fascination. To me it looks a bit like a metal-oxide surface layer (we call them metallic sheens) that develops over anoxic water that contains dissolved Fe or Mn (see the film developing at the surface of a pool of water in the Toolik Lake region). My guess is that it is partly that and also a lot of fine glacial clays. Maybe lots of clays + metal oxides. I have poked many metal oxide films on the surface of stagnant water and it breaks in a more fractured sea-ice pattern than a star. Maybe the clay addition alters the surface tension to allow star formation. That is my best guess. Given that they see it in spring, it could support my idea because winter water under glaciers can go anoxic and stimulate Fe reduction which would produce the required dissolved Fe that produce the oxide at the surface. If there is a lot of carbon it could be lipids, maybe from the degradation of snow or ice algae. I don't know their oil content. Did they look for Fe or Mn? If there is a lot of either of those two, then it is a reasonable explanation.
Daniel Otto:
I saw your cryolist message. I'm actually working on a project that has one of its big focuses on carbon coming out of glaciers in meltwater. We also happen to have some extra room for water grab samples in our contracts since field work has been a bit slower than usual! Next time I am out that direction I could probably grab some samples. We are getting back ions, nutrients, and a bunch of carbon quality stuff. Very cool phenomena! I'm definitely curious to know where that stuff comes from and what causes that effect.
I suspect that what we are seeing is a surface tension effect. Since it doesn't work with sticks, etc, it's probably due to oils on your finger. Ask your friend to try placing a drop of oil on the surface and see what happens. Or, it could also be soap or hand cream residue that would change the surface tension.
Felix S Ng
Interesting. My suggestion: try to recreate the phenomenon in a lab (analogue or approximate) experiment? Then investigate more? There may be various usable jars of colloidal "oil+granular" paste/sauces in our kitchen... but dumping clay into a water tub should be relatively easy to do too.
Bruce RAUP
The video made me think of my junior high school experiment where a drop of oleic acid spread out on the surface of water, pushing aside some dust we'd put on the water first. But this looks a bit sub-surface, so probably different from, say, finger oils spreading out on water. But maybe finger oils have something to do with it. Do the tour guides do anything to prepare the surface or sub-surface conditions for this?
Tetsuo Sueyoshi
I had an impression that it's a similar phenomenon by surface tension,
something like these I found on YouTube:
...though I haven't figured out what makes the surface tension of the water
weaker around the finger for the case of glacier water ...
Before finding these videos, I found an educational material below,
unfortunately in Japanese only:
They put some explanation there.
Here is a translation by Translated with www.DeepL.com/Translator (free version):
1. if you put a little detergent solution in the center of the pepper powder spread on the surface of the water, the pepper will instantly turn into a doughnut shape. This is a good place to start. When sugar water is poured over the surface of the pepper, the donut-shaped pepper will try to return to its original shape. The surface tension of the water will pull the pepper powder out of the water and it will spread. Comparing the surface tension of water and kitchen detergent, the surface tension of kitchen detergent is weaker, so you can see that the kitchen When the detergent is applied, the pepper dust is attracted towards the water, which has a higher surface tension.
2. Also, sugar water has a stronger surface tension than water, so when the sugar water falls to the surface of the water, the surface tension is stronger and the pepper dust tries to return to its original state.
