FLORIDA GEOLOGICAL SURVEY


Water Temperature Geologic material is a good thermal insulator. It tends to buffer
changes in the temperature of spring water. Thus, spring water temperature does not vary
much and tends to reflect the average annual air temperature in the vicinity of the spring.
This temperature can range from 680F to 75F (200C to 24C), plus or minus several tenths
of a degree. Temperature plays a role in chemical and biological activity within the aquifer
and can help in determining residence time of the water in the aquifer.

Discharge Discharge, or springflow, is controlled by the potentiometric levels in the FAS.
Discharge generally changes slowly in response to fluctuations in the water levels in the
aquifer. Discharge is measured in cubic feet per second or gallons per day.

Other Field Data During sample collection, total water depth, sample depth, local geolo-
gy, adjacent land use and current weather conditions are noted at each spring. This gener-
alized information can be useful in helping to determine certain water quality-related issues
of the spring.

 Laboratory Analytes

Alkalinity The alkalinity of spring water is affected primarily by the presence of bicar-
bonate, hydroxide and carbon dioxide. Highly alkaline waters are usually associated with
high pH, dissolved solids and hardness which, when combined, may be detrimental to the
aquatic environment.

Biochemical Oxygen Demand Biochemical oxygen demand (BOD) is a measure of the
quantity of molecular oxygen utilized in the decomposition of organic material, during a
specified incubation time, by microorganisms such as bacteria. When the BOD is high, the
depletion of oxygen can have a detrimental effect on aquatic organisms. BOD is measured
in mg/L. In Florida, there is no set standard for BOD in groundwater.

Chloride (Cl-) Chloride is the most abundant constituent in seawater, and springs that
are tidally influenced have high chloride concentrations. Chloride is added to the atmos-
phere via marine aerosols from the ocean. In most of Florida's springs, chloride is intro-
duced to the spring system via rainfall. Chloride is chemically conservative and reacts very
little with spring water. When chloride concentrations in drinking water exceed 250 mg/L
it is considered unfit for drinking. This is the secondary standard established by the State
of Florida.

Color The color of spring water can be affected by factors such as the presence of metallic
ions, tannic acids, biological activity and industrial waste. Generally, spring water in
Florida is clear. Color measurements are made on filtered water samples so the true color
of the water is determined. Color is reported in either color units or Platinum Cobalt units
(Pt/Co). In Florida, the secondary (aesthetic) standard for groundwater is 15 color units.

Hardness The hardness of water is a function of the presence of calcium, magnesium, and
other alkali metal ions. The higher the calcium/magnesium content of the water, the hard-
er the water. Hard water forms insoluble residues on surfaces where evaporation has taken
place. Hard water, when used with soap, can also form residues on surfaces. The hardness
of water is expressed either in parts per million, or in milligrams per liter, and is usually a
measure of the calcium carbonate dissolved in the water.