What is Water Dissolved Oxygen

All we know that oxygen being in the air we breathe, but what about the liquids around us? We are not the only organisms that need oxygen to survive. Oxygen plays a major role in food preservation, water management, and environmental monitoring. It is important to remember that oxygen doesn’t just float around in the atmosphere but, it can also be present in liquids. This makes dissolved oxygen a key measurement parameter for many industries.

Dissolved oxygen is a measure of the amount of gaseous oxygen contained in water. Healthy waters that can support life must contain dissolved oxygen (DO). Dissolved Oxygen enters water by: direct absorption from the atmosphere. rapid movement from winds, waves, currents or mechanical aeration.

Dissolved oxygen is a vital parameter in the environmental monitoring of water quality. It is a great indicator of the general health of the ecosystem. As more organisms die, and eventually decay, it causes a bacterial growth spike. This spike results in an increase in DO use, and a decrease in the overall DO levels. Drops in DO can be enough to cause dead-zones to form, where all of the aquatic plants and animals in a body of water die off. Monitoring DO in aquaculture is done for similar reasons as well.

Laboratory measurements of DO can be direct, but it can also be used to monitor BOD, OUR, and SOUR. BOD (Biological Oxygen Demand) is used to help determine the biodegradable organic matter in water. This gives operators an idea of the general water quality, as well as the level of pollution in the sample. OUR (Oxygen Uptake Rate) is a quicker test than BOD that can be used as an indicator of biological activity of the sample. This is done by monitoring the oxygen consumption in the water. SOUR (Specific Oxygen Uptake Rate) is the amount of oxygen needed in mg/L microbes to consume one gram of food (waste). SOUR is usually monitored in sludge treatment.