Water that briny creates an osmotic pressure outward, IIRC. Arsenic would be washed out of the organisms rather than soaking in. And those flamingos have to be getting their drinking water from somewhere else.
“And those flamingos have to be getting their drinking water from somewhere else.”
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Ya think?
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Sorry, not true. Any such osmotic pressure is only in effect for a very short period of time before it equilibrates across the cell membranes. Same for the arsenic. Microbes adapted to fresh water and immediately placed in salt will mostly die, and brine microbes immediately placed in fresh water will basically explode. But over generations, osmotic pressure is of zero consequence.