Measurements ofDissolved Oxygen (DO)and Chemical Oxygen Demand (COD)in Tap Water,Ponds,and River Water in Our Life

In the present study,we measured dissolved oxygen (DO)and chemical oxygen demand (COD)in tap water, ponds, and river water in our life. The obtained data showed the difference values in various places. It is notable that the values of COD of the pond in site of Wakayama University were markedly increased from 2009to 2022. On the other hand, the evaluated DO and COD values of the Kishigawa River and the Hikata River in Wakayama Prefecture remained unchanged for long periods of time. Therefore, these values are considered to environmental indicators. It is expected that the studies of DO and COD measurements can be applied in chemistry class and themed research of high school.