How alpine streams work

In aquatic ecosystems, such as the world’s oceans, streams and lakes, numerous aquatic organisms, ranging from bacteria to fish, respire oxygen and exhale CO₂. These gases must therefore be continually “exchanged” from the atmosphere to the water and vice-versa. Because mountain streams often flow over steep drops and rugged terrain, this creates a lot of turbulence and causes air bubbles to be trapped in the water, appearing white (aka ‘white water’). These bubbles accelerate the gas exchange. Strikingly, the same mechanism is at work when white-capped waves appear on the surface of rough seas. Until now, scientists have ignored the contribution from air bubbles and have used the same approach to calculate gas exchange velocities in mountain streams than in calm lowland streams. via