These bubbles are pure oxygen that has been produced via photosynthesis by the green algal filaments and is still trapped as bubbles in the waters of its birth.
The carbon dioxide is dissolved in the water and is absorbed directly from the water. With the help of sunlight the green chloroplasts in the plant cells split the carbon dioxide to for carbohydrates and the oxygen is released as a waste byproduct. In this case it forms bubbles until it can be dispersed to allow our planet to breath.
In this case it is occurring at high altitude in a mountain region where there are enough animals shedding their waste to be able to provide the necessary nitrogen in the water for algae to thrive.
