Lake Ontario oxygen model. 1. Model development and application

Abstract

w A mathematical model for dissolved oxygen has been formulated for Lake Ontario. The lake is treated as one box during winter circulation but as two boxes (epilimnion, hypolimnion) during summer stratification; inflows, outflows, vertical transport across the thermocline, atmospheric reaeration, photosynthesis, and decomposition are considered. For each year, temperature data are used to estimate the vertical exchange coefficient and the thermocline depth as a function of time. Predictions of the oxygen model show reasonable agreement with observations for a 9-year period. This agreement provides some verification for the model and for the application of the oceanic stoichiometry of Redfield to lakes. Model predictions and observations suggest that oxygen is transported from the hypolimnion to the epilimnion and from the epilimnion to the atmosphere during summer stratification. Vertical transport accounts for ca. 10% of the hypolimnetic loss of oxygen.

Predicting changes in hypolimnetic oxygen concentrations with phosphorus retention, temperature, and morphometry

“…Because hypolimnetic oxygen depletion is accelerated by nutrient enrich-ment, resulting in deteriorating water quality (e.g. Edmondson 196 1, 1966;Dillon et al 1978;Lind 1987), several studies have attempted to develop models that can predict the rate at which oxygen is consumed within the hypolimnion (Lasenby 1975;Cornett and Rigler 1979;Walker 1979;Charlton 1980;Trimbee and Prepas 1988). The empirical link between surface water productivity and oxygen consumption described in these models is supported by studies of the individual processes (respiration, photosynthesis, and the turbulent transport of oxygen) affecting oxygen concentrations (0,).…”

Lake Ontario oxygen model. 2. Errors associated with estimating transport across the thermocline

“…Seasonal estimates of ktil using methods 1,2, and 2A are given in Table IIC for 6 years for Lake Ontario. Overall, there is not much difference in the estimates obtained for method 1 [that used by Snodgrass and Dalrymple (17)] and method 2 (that which accounts for entrainment). Accordingly, the error associated with not considering entrainment in estimating feth (17) is small.…”

“…Overall, there is not much difference in the estimates obtained for method 1 [that used by Snodgrass and Dalrymple (17)] and method 2 (that which accounts for entrainment). Accordingly, the error associated with not considering entrainment in estimating feth (17) is small. A larger difference results between methods 2 and 2A than between methods 1 and 2; hence, the interpretation of what temperature parameter to use for describing the temperature of the water being entrained into the epilimnion is quite critical.…”

Predicting the potential long-term influence of climate change on vendace (Coregonus albula) habitat in Bassenthwaite Lake, U.K.

“…The LOX model is physically based and conceptualises a lake as consisting of two layers, a well‐mixed epilimnion that lies above a quiescent hypolimnion. It is based on formulations suggested by Snodgrass & Dalrymple (1985) and Stefan & Fang (1994). The mass balance equations used to describe oxygen concentration in these layers are …”