What is Alkalinity

1

• What is Alkalinity?
• Alkalinity is the measurement of a body of
  waters resistance to the lowering of pH when
  acids are added to the water.
• Alkalinity
• Rain and snow melt are important sources of acid
  addition.
• Alkalinity, like temperature and pH, has a strong
  impact on the kinds of aquatic life that will
  survive in water.
• Alkalinity is measured in ppm (mg/L) as CaCO3.
• This measurement is suggested for intermediate
  and advanced students.

2

• Significant Values
• Fresh water has alkalinity of 20 - 200 ppm as
  CaCO3.
• Levels between 100 - 200 ppm as CaCO3 will
  stabilize the pH level in a stream.
• Sea water has alkalinity of 100 - 125 ppm as
  CaCO3.

3

• Instrumentation
• Alkalinity Test Kit (See Toolkit)
• Distilled water bottle
• 100 mL graduated cylinder
• Sample bottle
• Latex gloves
• Safety goggles

4

• Instrument Placement
• Take water sample near the same location as the
  water temperature measurement, weekly at the same
  time of day.
• Collect water in the sampling bottle.

5

• Quality Control Procedure
• The requirement for the calibration procedure has
  been dropped for 2001.
• However, it is required that chemicals not be
  used past their expiration date.
• It is highly recommended that the chemicals be
  replaced at least once per calendar year if you
  are making weekly measurement this will not be a
  problem.
• You may be required to enter chemical purchase
  dates in the future.

6

• Element Reporting
• Make measurements weekly, at the same time of
  day.
• Complete the Hydrology Investigation Data Work
  Sheet for Alkalinity.
• Take the average of the alkalinity values
  measured by the student groups. If the recorded
  values are all within 6.8 mg/L (Hach kit) or 4
  mg/L (LaMotte kit) of the average, submit the
  average value to the GLOBE Student Data Server.