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Quality of a River - Water Quality
Chemistry: Alkalinity


Alkalinity is a measure of the water's capacity to buffer against large changes in pH. It generally is determined by the amount of minerals such as calcium and magnesium carbonate. Alkalinity is a basic (forgive the pun) measure of a stream's biological productivity.

Some common sources include:

  • Dissolved compounds in rain and snow
  • Dissolution of compounds in soil, sediments, and bedrock
  • Byproducts from biological processes in the stream

Spring-fed streams running through limestone topography have high alkalinity and high levels of dissolved minerals, especially calcium carbonate, which is linked to the high productivity of aquatic organisms in ways scientists don't fully understand. These productive "hard-water" streams, because of their geology, are often called "limestone" streams.

Streams originating in bogs, granitic or sandy lakes, and other non-limestone topography, are typically low in alkalinity, with few dissolved minerals. While they may hold large fish, their productivity in terms of pounds of fish per acre or similar indicator, is lower in comparison to a limestone stream.

Because we don't fully understand the role of alkalinity to river system productivity, we can't fully appreciate how our activities impact this relationship.


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Introduction
Flow
Shape
Connections
Quality
Description
Temperature
Oxygen
Alkalinity
Nutrients
Sediment
Contaminants
Status
Life
Summary
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