In mine closure, artic mines will protect their tailings and waste rock using thermal covers that insulate them from heat, and allow permafrost to form, thus entombing the PAG (Potentially acid generating material - acid drainage presents orange like this too). The frost prevent oxygen (and dissolved oxygen - from water) from interacting with the material, and causing the acid-generating reaction.
With the thawing of natural permafrost, iron that was frozen (as water soluble reduced iron) is released and then oxidized, causing the orange water.
It’s a geochemistry issue.
In mine closure, artic mines will protect their tailings and waste rock using thermal covers that insulate them from heat, and allow permafrost to form, thus entombing the PAG (Potentially acid generating material - acid drainage presents orange like this too). The frost prevent oxygen (and dissolved oxygen - from water) from interacting with the material, and causing the acid-generating reaction.
With the thawing of natural permafrost, iron that was frozen (as water soluble reduced iron) is released and then oxidized, causing the orange water.
So it’s rust.
Rust, or rusty water with battery acid pH
Battery acid is extremely concentrated compared to that water. Iron can only precipitate if it is very dilute.
https://pubs.usgs.gov/publication/70022523#:~:text=Extremely acidic mine waters with,Mine at Iron Mountain%2C CA.
Yes, that was measured somewhere in some amount. But not in this picture here for several reasons.
If left for itself, that is the concentration it tends to go to since the water evaporates, leaving the H2SO4 behind.