Glacier Front - Mysterious Bubbles - East Greenland

In the background is the end of the ice sheet where blocks of ice fall off into the sea to melt and/or be carried away. The foreground is an area of shallow water just a few inches deep where in some areas there were steady streams of bubbles rising to the surface, you can see four of them at the bottom of this picture. The bubbles were small but raising rapidly like those produced by an air pump in an aquarium. Quite how any air came to be trapped and escaping in this way was another puzzle that I couldn't answer.