Testing CO2 Rates

The rate at which carbon-dioxide is produced in an aquatic environment may be measured using the so-called "carbon-dioxide diurnal rate of change curve method" (see the reference below). This method allows limnologists to measure changes in the rate of photosynthesis or respiration for an aquatic ecosystem.

The method involves using pH meters to determine the diurnal variation of pH in the water. A sample of water is bubbled with an inert gas (such as nitrogen) in order to raise the Ph level. The sample is then titrated with a solution of distilled water that has been saturated with carbon-dioxide (at standard atmospheric pressure). The titration allows a researcher to establish a relationship between pH and total dissolved carbon-dioxide.

Once this relationship is known, then the limnologist may measure changes in the pH of water samples, and translate that change in pH into a corresponding change in the concentration of carbon-dioxide.

Beyers, R. J. 1963. The metabolism of twelve aquatic laboratory microsystems. Ecol. Monogr. 33: 281-306.
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The Geometry Center Calculus Development Team

A portion of this lab is based on a problem appearing in the Harvard Consortium Calculus book, Hughes-Hallet, et al, 1994, p. 174

Last modified: Fri Jan 5 09:51:10 1996