Résumé :
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This research was undertaken to develop and apply a mathematical model of the water quality in large lakes, particulary Lake Huron and Saginay Bay and Lake Erie. A mathematical model of phytoplancton biomass was developed which incorporates both phytoplancton and zooplancton as well as phosphorus, nitrogen and silica nutient forms. Extensive water quality data for lake Huron and Sagina Bay was analyzed and statistically reduced. The model was then calibrated by comparison of computed results to these data. An exhaustive treatment of the kinetics employed for modelling the eutrophication process is presented. The sensitivity of the model to some of its key parameters is examined. In addition, responses of water quality in Lake Huron and Sagina Bay system to variations in total phosphorus inputs are projected. A mathematical model was developed for analysis of the interactions between nutrient discharges to Lake Erie, the response of phytoplancton tothese discharge, and the dissolved oxygen, phytoplancton chlorophyll for diatoms nondiatoms, zooplancton biomass, nutrient concentrations in available and unavailable forms and inorganic carbon are considered in the model. Extensive Comparison of data from 1970 and 1973-74 to model calculations served for 1975, a year when no anoxia was observed. Recent developments in phytoplancton growth and update kinetics are included in this analysis. The methods of sedimentary geochemistery are expanded to include int his analysis of sediment oxygen demand within the framework of mass balances. Projected effects of varying degrees of phosphorus removal on dissolved oxygen, anoxic area, chlorophyll, transparency and phosphorus concentration are presented.
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