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Name: Patricia 
Status: student
Grade: 9-12
Location: VA
Country: USA
Date: Fall 2012

I am currently designing a project which involves lemna minor and varying concentrations of atmospheric carbon dioxide, however I am having trouble coming up with a way to maintain co2 levels constant over a period of several days..... Is there anyway to go about this?


The best way that I know to maintain a constant concentration of carbon dioxide is to slowly release carbon dioxide gas from a gas cylinder through a chamber where you would keep your plants.

To vary the carbon dioxide concentration, you could use tanks with different concentrations or you could use a GPT (gas phase titration) system which precisely mixes a gas with air to achieve a particular concentration.

The GPT system I mention above is not commonly available in high schools, but you might be able to borrow one from a company, university, or laboratory that uses them.

Gas cylinders of various sizes and gas concentrations are available from a large number of companies (AIRGAS, Scott, AGA, etc.), but tend to be costly.

David R. Cook Meteorologist Atmospheric and Climate Research Program Environmental Science Division Argonne National Laboratory

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