Water contacting air is what you want. Without geeking out too much, the pressure on your water is greater with depth. This higher pressure allows your deep water to hold more gasses in suspension. As the water rises, it will start to release those trapped gasses. Also, water in contact with air will re-oxygenate in very short order. If sprayed, it will saturate in 18 to 24 inches of air travel. You will loose some water to evaporation, but if O2 is your only problem, spraying your deep water through the air will re-oxygenate that moved water. An outboard motor will also move a lot of water in a crisis, exposing it to the air.
