When assessing Dissolved Oxygen in water, which physical condition is NOT a factor?

When assessing Dissolved Oxygen (DO) levels in water, water purity is not a direct factor influencing the solubility of oxygen. Instead, DO is primarily affected by physical conditions such as atmospheric pressure, salinity, and water temperature.

Atmospheric pressure plays a significant role because the higher the pressure, the greater the amount of oxygen that can dissolve in the water. Water temperature is crucial as well; warmer water typically holds less dissolved oxygen due to decreased solubility at higher temperatures. Salinity also affects the solubility of oxygen; as salt concentrations increase, the capacity of water to hold dissolved gases like oxygen decreases.

While water purity can influence the overall quality of water and potentially the biological processes that consume oxygen, it does not directly dictate the physical conditions for dissolved oxygen levels in the way that the other factors do. Thus, it is correct to say that water purity is not a relevant factor in the assessment of dissolved oxygen in water.