Fertilizers, sewage, and disturbance of the land increase phosphorus levels. It also acts to eutrophy bodies of water. Dissolved oxygen is necessary for survival of aquatic organisms. It dissolves in water from the atmosphere and is produced during photosynthesis of water plants. Oxygen is removed from water as bacteria decompose organic materials.
Temperature is important to water because gases dissolve better in cold water than warm.
Oxygen levels will drop as water warms up. The rate of photosynthesis and plant growth also increase. Metabolic rates increase in warm water and even more oxygen is needed. Goggles should be worn when using acids or bases. To learn how water is tested and what the tests indicate.