Lake Ontario oxygen model. 1. Model development and application

Allochthonous and autochthonous factors involved in oxygen depletion from the hypolimnial region of lakes are discussed. The development of a two-box model to predict the seasonal and annual oxygen variations in the epilimnion and hyperlimnion of Ontario lake is described. The model required estimates of the thermocline depth and vertical transport coefficient across the thermocline together with surface temperature. The application of the model utilizing temperature data routinely collected over a nine year period between 1966 and 1974 is reported. Model predictions showed reasonable agreement with observations. The model and observed data implied that oxygen was pumped from the hypolimnion to the epilimnion and the atmosphere throughout summer stratification. Vertical transport accounted for approximately 10 per cent of the mean hypolimnetic oxygen depletion rate of 1.3 g oxygen per m2 per day.