The amount of oxygen that can be dissolved in water is a function of temperature, concentration of dissolved solids, and atmospheric pressure. An equation developed by APHA (1985) is used to calculate the saturation concentration of dissolved oxygen:
Oxsat​=exp[−139.34410+Twat,K​1.575701∗105​−Twat,K2​6.642308∗107​+Twat,K3​1.243800∗1010​−Twat,K4​8.621949∗1011​] 7:3.5.3
where Oxsat​ is the equilibrium saturation oxygen concentration at 1.00 atm (mg O2​/L), and Twat,K​ is the water temperature in Kelvin (273.15+°C).