Transcript Alkalinity
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 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. 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. 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 CaCO3 (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 CaCO3 Sea water: 100 – 500 ppm as CaCO3 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 (NaHCO3) Standard to check accuracy in technique Making the NaHCO3 standard is a 2-part dilution process For Help AMSTI-GLOBE www.amsti.org/globe Lynn Vaughan AMSTI-GLOBE Resource Specialist [email protected] Robin Nelson AMSTI-GLOBE Administrator [email protected] The GLOBE Program www.globe.gov Jerry Cobbs AMSTI –GLOBE Technology Specialist [email protected]