Geology topics

Research about central Florida

Source-linked reports with geographic coverage including central Florida.

4 recordsLinked to original sources

USGS1996

Hydrology of central Florida lakes, a primer

Lakes are among the most valued natural resources of central Florida. The landscape of central Florida is riddled with lakes—when viewed from the air it almost seems there is more water than land. Florida has more naturally formed lakes than other southeastern States, where many lakes are manmade, created by building darns across streams. The abundance of lakes on the Florida peninsula is a result of the geology and geologic history of the State. An estimated 7,800 lakes in Florida are greater than 1 acre in surface area. Of these, 35 percent are located in just four counties (fig. 1): Lake, Orange, Osceola, and Polk (Hughes, 1974b). Lakes add to the aesthetic and commercial value of the area and are used by many residents and visitors for fishing, boating, swimming, and other types of outdoor recreation. Lakes also are used for other purposes, such as irrigation, flood control, water supply, and navigation.

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USGS1993

Biogeochemical and hydrological processes controlling the transport and fate of 1,2-dibromoethane (EDB) in soil and ground water, central Florida

Widespread contamination of ground water in central Florida by 1,2-dibromoethane (EDB) has resulted because of its heavy usage as a soil fumigant during a 20-year period, its relatively high aqueous solubility, and the low sorption capacity of the highly permeable sandy soils lacking organic matter. Two models were used to improve understanding of biogeochemical and hydrological processes that control the transport and fate of EDB in soil and ground water. First, a mass-balance model was developed to estimate the maximum concentration of EDB in ground water resulting from known application rates of EDB. Key processes that were quantified in the model included volatilization, diffusion of EDB vapor in soils, partitioning between aqueous and gaseous phases, sorption of EDB vapor on organic carbon and soil particles, chemical and biological degradation reactions, and nonreversible binding of EDB to soils. Model calculations using an EDB half-life of 0.65 year closely reproduced the maximum observed concentrations in ground water, 37 and 0.22 micrograms per liter, at downgradient sites in two study areas in central Florida. Maximum concentrations of EDB in ground water also were estimated in a second model that incorporated an analytical solution to the three-dimensional advection-dispersion equation for instantaneous point sources of EDB entering the flow systems in the two study areas. The model used an EDB half-life of 0.65 year (obtained from the mass-balance calculations), mean ground-water flow velocities of 0.6 to 1 meter per day, coefficients of longitudinal hydro-dynamic dispersion of 0.6 to 1.0 square meter per day, and coefficients of transverse hydrodynamic dispersion of 0.1 square meter per day. Peak concentrations of EDB in ground water calculated from the analytical model agreed closely with observed peak concentrations measured from 1983 through 1987.

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USGS1965

Radiocarbon determinations for estimating groundwater flow velocities in central Florida

Carbon-14 activity was determined from HCO 3 - in samples of groundwater obtained from the principal artesian aquifer in Florida. From these data the "age" of water obtained from a series of wells, each progressively farther down gradient on the piezometric surface, was established. Relative carbon-14 ages indicated a velocity of groundwater movement of 23 feet (7 meters) per year for about 85 miles (137 kilometers) of travel. A velocity of 23 feet per year was calculated independently from Darcy's law.

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USGS1963

Preliminary results of a study of calcium carbonate saturation of ground water in central Florida

The departure of ground water from equilibrium with calcite is being studied in central Florida . Measurements of pH, temperature, and concentration of bicarbonate made in the field are used with standard laboratory analyses of water samples to calculate an ion activity product (K) for calcium carbonate . The calculated Kiap is compared with the equilibrium constant (Keq) for calcite to determine the departure from equilibrium. The calcium concentration is lowest in the area of the highest piezometric surface. Some of the highest concentrations of bicarbonate are in the area of low calcium . In about half of the area of study , the water is undersaturated with respect to calcite. This indicates that solution of limestone can occur several hundred feet below the water table.

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