Assertion: aquifer's water | /r/HasProperty | exposed to oxygen
Facets:
value: in the air
type: LOCATION
Source sentences:
text: When water that contains large concentrations of dissolved iron is pumped from a well and exposed to oxygen in the air, the dissolved iron reverts to an insoluble form that is visible as a black to reddish-brown precipitate, which clouds and discolors the water and stains porcelain fixtures and laundry.