Dissolved oxygen refers to measuring the solubility of free oxygen molecules in water. The concentration of dissolved oxygen is an important indicator of the health of aquatic ecosystems, as oxygen is essential for almost all forms of life. The dissolved oxygen in water mainly comes from two sources: atmosphere and photosynthesis; The main factors affecting dissolved oxygen are temperature, altitude, salinity, and flowing water.

The concentration of dissolved oxygen is determined by the intended use of the aquatic ecosystem. In the industrial field, in order to prevent corrosion and boiler scaling, the supply water must ensure that the dissolved oxygen is at a low level. The high level of dissolved oxygen in water can improve the taste of drinking water. However, excessive dissolved oxygen levels can also increase the degree of pipeline corrosion. In the aquaculture industry, if the dissolved oxygen level is too low, fish in the water will suffocate and die; In sewage treatment plants, if the dissolved oxygen level is low, some bacteria will die and the degradation process will stop; Therefore, monitoring the concentration of dissolved oxygen plays an important role in ensuring process efficiency.