Which of the following is an example of a chemical parameter measured in surface water testing?

Dissolved oxygen is considered a chemical parameter because it is a measure of the amount of oxygen that is dissolved in water, which is crucial for the survival of aquatic organisms. This parameter is essential for assessing the quality of water since it reflects the water’s ability to support life. In surface water testing, chemical parameters like dissolved oxygen are indicative of various processes, including photosynthesis and decomposition, and can affect aquatic ecosystems significantly.

In contrast, water temperature is a physical parameter that can influence chemical and biological processes in the water but does not directly measure a chemical substance. Flow rate pertains to the physical dynamics of water movement and is not a chemical measurement. Fish diversity relates to biological assessments and the variety of species present in the water body, which is not a chemical characteristic but rather an ecological aspect.