Question was:
"how large an area is typically impacted by limited mixing and diffusion?" Or, "If the cold water in the open hole has a concentration of 13-14 mg/L of oxygen, at steady state, how far from the hole must you be before the oxygen level is lethal, assuming no additional sources of oxygen?"
My commentary - To my knowledge very little testing has been done for the amount of water current movement that occurs from a bottom diffuser aerator. Depth placement of the diffuser I think will have a significant influence on how far the diffuser currents spread. One has to keep in mind that water that is at a uniform 39F will move and spread a lot further distance compared to summer water temperatures. IMO the water will spread a lot further than one would expect.
Solar radiation through the iced shoreling areas causes water current movement.
If you can only do "partial aeration" of a pond, and the pond is getting close to winterkill low oxygen conditions, are the fish capable of sensing the column of aerated water and congregating there until conditions improve?
After thinking about this especially during iced winter conditions, I believe that the sound of the rising bubble plume and is perceived a long distance by fish. I don't think we realize how sensitive fish are to their surroundings. Fish can readily feel water movement, current and underwater sounds. This is the habitat that they grow up in. This is their adapted world. For them, sensitivity is critical to survival. IMO bubbling action at one end of a 1 acre ice covered pond will be perceived at the opposite end of the pond. The bubbling sound in the middle of a 5 acre pond during calm winter ice cover may even be perceived throughout the entire pond.
