Regional Geology and the Chemical and Trophic State Characteristics of Florida Lakes

Abstract

A limnological survey of 165 Florida lakes was conducted between September 1979 and August 1980 to determine their chemical and trophic state characteristics. A wide range of limnological conditions was documented. Average lake pH values ranged from 4.1 to 9.2 and average total alkalinity concentrations ranged from 0 to 204 mg/L as calcium carbonate (CaCO₃). Average specific conductance values ranged from 11 to over 5600 μS/cm at 25° C. Mean total nitrogen concentrations ranged from 0.063 to 4.6 mg/L and mean total phosphorus concentrations ranged from 3 to 834 mg/m³. Although lake trophic states ranged from oligotrophic to hypereutrophic, Florida lakes as a group can be characterized as productive, softwater lakes. Over 75 percent of the sampled lakes had total alkalinity concentrations below 40 mg/L as calcium carbonate and total hardness concentrations below 75 mg/L as calcium carbonate. Most of the sampled lakes were either mesotrophic (52 percent) or eutrophic (35 percent) because total phosphorus levels exceeded 10 mg/m³ in over 75 percent of the lakes. The mineral composition of the lakes seems to be strongly related to Florida's geologic and physiographic development.