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Deoxygenation of a Florida lake during winter mixing
Author(s) -
Whitmore Thomas J.,
Brenner Mark,
Rood Brian E.,
Japy Kate E.
Publication year - 1991
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1991.36.3.0577
Subject(s) - anoxic waters , water column , deoxygenation , stratification (seeds) , environmental science , turbidity , halocline , epilimnion , chemocline , surface water , oxygen , oceanography , hydrology (agriculture) , environmental chemistry , geology , chemistry , nutrient , hypolimnion , biology , eutrophication , environmental engineering , botany , salinity , germination , seed dormancy , geotechnical engineering , organic chemistry , dormancy , biochemistry , catalysis
Johnson Pond occupies a small, deep, solution basin ( A = 2.2 ha, z max = 17.5 m) in north Florida. This warm, monomictic lake gains and loses 5,945 cal cm −2 annually. Dissolved color and algal turbidity limit light and heat penetration, causing steep gradients in temperature, oxygen, dissolved inorganic C, and remobilized sedimentary P during stratification from March through November. Water below 5 m is cool (<14°C) and anoxic throughout the year. Weak chemical gradients can persist in the water column during homothermy. The lake is ineffectively mixed because of morphometry, wind sheltering by trees, and the brevity of homothermy. An unusual consequence of winter mixing is very low oxygen concentrations in surface waters (< 1 mg liter −1 ). Surface‐water oxygen is diluted by upward mixing of deeper anoxic waters, and O 2 is consumed by BOD and reduced Fe and S. Deoxygenation at mixis occurs in several African lakes, but is unreported in warm, monomictic lakes of North America.