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SIMULATION OF DISSOLVED OXYGEN PROFILES IN A TRANSPARENT, DIMICTIC LAKE
Citation:
Stefan, H., X. Fang, D. Wright, J. Eaton, AND J. McCormick. SIMULATION OF DISSOLVED OXYGEN PROFILES IN A TRANSPARENT, DIMICTIC LAKE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/234.
Description:
Thrush Lake is a small, highly transparent lake in northeastern Minnesota. rom 1986 to 1991, vertical profiles of water temperature, dissolved oxygen, chlorophyll a concentration, underwater light irradiance, and Secchi depths were measured at monthly intervals during the ice-free period. verage Secchi depth was 7.5 m. Metalimnetic oxygen maxima were observed every summer. he oxygen peaks were related to Chl a distribution and water transparency. eterministic one-dimensional model was developed to simulate vertical dissolved oxygen (D.O.) profiles on a daily time @e throughout the open-water season. he model includes oxygen production by photosynthesis and surface reaeration as well as oxygen consumption by plant respiration and biochemical and sedimentary oxygen demand. he measurements suggest that the model must use different Chl a and sedimentary oxygen demand values in the surface mixed layer and below the surface mixed layer in conjunction with high transparency to obtain a metalimnetic oxygen maximum. easured Chl a values are specified as input to the D.O. model. he model reproduces measured D.O. distributions with a standard error of 1.4 mg liter-1 and shows the observed metalimnetic oxygen maxima. odel output changes only slightly with starting date of simulation and initial D.O. values. imulated water temperature and D.O. distributions in the lake, especially the surface mixed-layer depth and the metalimnetic oxygen maxima, are sensitive to changes in water transparency.