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Lateral Solute Concentration Gradients in Stratified Eutrophic Lakes
Author(s) -
Stauffer Robert E.
Publication year - 1985
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr021i004p00554
Subject(s) - hypolimnion , eutrophication , epilimnion , thermocline , phosphorus , chemocline , oceanography , water column , environmental science , phytoplankton , oxygen , sediment , hydrology (agriculture) , geology , ecology , nutrient , chemistry , biology , geomorphology , geotechnical engineering , organic chemistry
Lateral concentration gradients in dissolved oxygen and phosphorus were studied in the metalimnion of Lake Mendota and the hypolimnion of Green Lake, Wisconsin. Oxygen concentrations were invariably lower (by up to 4.5 mg/L) in the 3‐m interval overlying shelf sediments as compared to adjacent stations in deeper water. Conversely, phosphorus concentrations were up to 65 mg/m 3 higher overlying the shelves. In Mendota, the “shelf shift,” −ΔO/ΔP, was low as compared to expectations based on Redfield's equation for the aerobic oxidation of sedimenting phytoplankton; this difference indicates a net sediment release of P under aerobic conditions, corroborating laboratory studies. For Lake Mendota a phosphorus profile at the deep hole station underestimates total lake phosphorus by circa 3% in midsummer. Because of its elongated asymmetric basin and related factors, the deep hole sampling bias is larger (circa 15%) for Green Lake. Based on lateral oxygen gradients and flux‐gradient computations, the lateral eddy diffusivity is 2 × 10 5 m 2 day −1 in the metalimnion of Mendota and the hypolimnion of Green Lake.