THE FLORIDA STATE UNIVERSITY ARTS AND SCIENCES ...

CHAPTER SEVEN
7. APPLICATION TO JACKSONVILLE, FL
Three study areas are considered; Eggleston Heights, Julington Creek and Lake Shore.
The areas are subdivisions within the city of Jacksonville which is a part of Duval County
and under the St Johns River management district. This region is composed of well
drained soils. The primary aquifer for drinking water is the Floridian aquifer which is
overlain by the surficial aquifer. In most of Duval County, the surficial aquifer system is
divided into two water-bearing units, the upper water-table unit and the lower limestone
unit. These two units are separated by sediments of low permeability and water cannot
easily move from one unit to the other.
The surficial aquifer system ranges in thickness from less than 10 ft (3.03 m) in the St.
Johns River Valley to about 100 (30.3 m) ft in western Duval County (Fairchild, 1972)
and is separated from the underlying Floridan aquifer system by the intermediate
confining unit. The water-table unit is the upper part of the surficial aquifer system and
consists of sediments ranging from 25 ft (7.5 m) to 50 ft (15.15 m) that were deposited
during the formation of the marine terraces and beach ridges associated with glaciation..
Geologically the surficial aquifer system is composed of undifferentiated fine to medium-
grained quartz sands, siliciclastics, fine to coarse grained sand but could contain thin beds
of sandy clay (Miller, 1997; Davis, 1998; Belanger et al., 2009)
The three statistical methods developed in this work are used to estimate a denitrification
rate; the methods while mainly statistical have also included the use of stable isotopes.
All the methods are applied to the three study areas and results are compared to
understand the importance of denitrification in the area.
As this work is primarily concerned with denitrification in saturated zone of the surficial
aquifer the water filled porosity is considered to be 100 percent. Since temperature of the
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