Dissolved oxygen is oxygen dissolved in water and it is an environment indicator as important as pH in the measurement of the water quality of rivers and lakes. In lakes, a massive proliferation of phytoplankton caused by a red tide may consume almost all the dissolved oxygen in the water, resulting in the deaths of massive numbers of fish and shellfish from suffocation due to the lack of dissolved oxygen. In recent years,
the amount of dissolved oxygen in culture solutions used in cell culture processes is being controlled. This chapter describes what dissolved oxygen is and methods for measuring dissolved oxygen levels.
