RICHARD – Lake Monitoring
Richard watched a dissolved oxygen analysis and measured how much oxygen was in a lake. But why is dissolved oxygen important in lakes and in streams? For that matter, what is dissolved oxygen? How does it get into water?

Well, never fear, we’re here to tell you what you need to know about dissolved oxygen!

Dissolved oxygen is the amount of oxygen trapped in between the molecules of water.

Dissolved oxygen gets into water three ways:
1. It is diffused from the surrounding air. This means that the oxygen in the air around the lake or stream passes from the air into the water.

2. It is added to the water by aeration. Aeration is moving water very quickly. Have you ever shaken a bottle of water and lots of bubble appeared? That’s aeration. Air is trapped between the molecules of the water.

3. It is a waste product of photosynthesis. As animals, when humans breathe our body keeps the oxygen from the air around us, but carbon dioxide is waste. Photosynthesis is the way plants breathe, but it is the opposite of the way animals breathe. They take in air but only keep the carbon dioxide. Even water plants do this, so the oxygen they waste is released into the water.
Water where plants and animals live needs enough dissolved oxygen. Streams keep themselves clean only when they have enough oxygen to support the plants and animals that eat waste products and move dirt and so on. Too little oxygen, even for only a few hours, can result in large areas of fishkills.

Even too much dissolved oxygen can be a problem, but this doesn’t happen very often. If too much oxygen gets into the water, bubbles form and get into the blood and breathing organs of fish and animals. These bubbles are called emboli.