What is Alkalinity? the measurement of the buffering capacity of a body of water that is, a body of water’s resistance to the lowering of pH when acids are added to the water the result of minerals that dissolve from rocks and soil as water flows through them

A lake with high alkalinity can neutralize the acidity of the rain thus maintaining a steady pH. Aquatic life – like fish – are able to function normally. A lake with low alkalinity will not be able to neutralize the acidity of the rain so pH will drop. Aquatic life – like fish – will suffer or, perhaps, die.

What factors affect Alkalinity? Geology & Soils: High - limestone and sedimentary rocks (like calcite) and carbonate-rich soils Low – igneous rocks like granite and carbonate-poor soils

What factors affect Alkalinity? Changes in pH: Well buffered streams are not very susceptible to changes in pH Poorly buffered streams cannot tolerate even small changes in pH

What factors affect Alkalinity? Sewage Outflow: Wastewater that contains cleaning agents, whether from homes, industries, etc., can boost the alkalinity of a water body

How is Alkalinity measured? in terms of either ppm or mg/L of CaCO 3 (calcium carbonate) equivalent units: 1ppm = 1mg/L by titration adding a solution of known strength using a titrator measuring the quantity needed to complete the reaction

Sample Collection & Reporting Rinse sample bottle 3 times with sample water Follow kit instructions. Repeat 3 times. Alkalinity values should agree within the precision of the kit (  1 drop of titrant).

What is normal Alkalinity? Fresh water: 20 – 200 ppm as CaCO 3 Sea water: 100 – 500 ppm as CaCO 3 Waters with >100ppm are considered “well buffered” and the pH will remain relatively stable.

Quality Control Procedure: Track dates of chemical purchase. Do not use chemicals past their expiration date. It is recommended that chemicals be replaced at least once a year Periodically use a Baking Soda (NaHCO 3 ) Standard to check accuracy in technique Making the NaHCO 3 standard is a 2-part dilution process

Step 1: Measure 1.9g of baking soda. Be sure the baking soda is dry! Add to 500mL graduated cylinder Fill to 500mL with distilled water and transfer solution to beaker. Mix well. Baking Soda (NaHCO 3 ) Standard

Step 2: Measure 15mL of NaHCO 3 solution and pour into a clean 500mL graduated cylinder. Fill to 500mL with distilled water. The alkalinity of the Baking Soda Standard should be 84 ppm as CaCO 3 (+/- 1)

For Help AMSTI-GLOBE Lynn Vaughan AMSTI-GLOBE Resource Specialist Robin Nelson AMSTI-GLOBE Administrator The GLOBE Program Technology Specialist Jerry Cobbs AMSTI –GLOBE Technology Specialist