> Chlorinated and fluorinated compounds, and other similarly constructed organic compounds are DNAPL - dense non aqueous phase liquids. They sink. They hit the water table, and keep sinking, not only below the water table, but further. Finding cracks in the bedrock and they keep sinking. It is almost impossible to get at them to clean them all up . Some small fraction of the DNAPL pollutants may be transported with the ground water, the rest stays and goes deeper. And you can't get at them.
This sounds like a self-solving problem: pollutants sinking deep, well past water table, near-impossible to get at, never to be seen again (and presumably recycled by Earth's geology in a hundred thousand years). What am I missing?
> They are also somewhat volatile, so they sometimes migrate up. Sometimes as gases.
Also, I can imagine that while they stay on the bottom they still contaminate some water above slightly and continuously since molecules in liquids generally like to move around a bit.
This sounds like a self-solving problem: pollutants sinking deep, well past water table, near-impossible to get at, never to be seen again (and presumably recycled by Earth's geology in a hundred thousand years). What am I missing?