Find flux of CO2: convert (μmolCO2 (mol air)^-1) to (mgC)(m^-2 of ground hr^–1)

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SUMMARY

The discussion focuses on converting CO2 concentration measurements from a data logger, recorded in (μmolCO2 (mol air)^-1), to a flux measurement in (mgC)(m^-2 of ground hr^–1). The user has obtained trendline equations for both closed and clear chambers, indicating the rate of CO2 change. The slope of the trendline represents the rate of change of CO2 concentration over time, confirming that it is expressed in (μmolCO2 (mol air)^-1) per second. The user requires additional data, specifically the volume of the chambers, to complete the flux calculations.

PREREQUISITES
  • Understanding of gas concentration units, specifically (μmolCO2 (mol air)^-1)
  • Familiarity with linear regression and trendline equations
  • Knowledge of photosynthesis measurement techniques in ecological studies
  • Basic principles of flux calculations in environmental science
NEXT STEPS
  • Calculate the volume of the chambers used in the experiment
  • Learn about converting CO2 concentration to carbon flux using the appropriate formulas
  • Explore the implications of background CO2 emissions in ecological measurements
  • Review methods for measuring photosynthesis rates in different environmental conditions
USEFUL FOR

Ecologists, environmental scientists, and researchers conducting experiments on photosynthesis and carbon flux measurements in terrestrial ecosystems.

mroldboy
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Homework Statement


I am doing an experiment to find the difference in photosynthesis between different areas of grass.

I have and am taking more measurements. But essentially I need to convert the data I have into a flux per area over time.

the data logger records the data of CO2 concentration in (μmolCO2 (mol air)-1). I had it set to do so every second and recorded data fro 4-5 minutes.

I have the slope of the trendline, but I am unsure what that slope is.

Is the slope (μmolCO2 (mol air)-1) per second since its rise/run?


Homework Equations


equations of the data I have

closed chamber: y = 2.3778x + 588.26

clear chamber: y = -0.3184x + 399.19


The Attempt at a Solution



basically I want to find how much CO2 was used. so if I have X amount of CO2 being emitted from the ground that is my background noise. I did that with a closed chamber so no light got in and therefor no photosynthesis occurred. Then measured the same grass with a clear chamber and got a decrease. This decrease should be more since there was still background noise. So the grass was using at least as much CO2 as was emitted from the ground plus some more.

I can't actually do the calculations since I am missing an important piece of data in the volume of the chambers. which were different sizes as well.

I want my flux in (mgC)(m^-2 of ground hr^–1)

Can anyone give me a basic walkthrough of how to do this?
 
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mroldboy said:
I have the slope of the trendline, but I am unsure what that slope is.

Is the slope (μmolCO2 (mol air)-1) per second since its rise/run?

Yeah. The slope of the graph is the rate of change of CO2 concentration with time. Therefore, it has dimensions of [concentration]/[time] in the units you happen to be using for those two quantities (which you indicated).
 

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