Carbon dioxide circulates naturally in Earth’s atmosphere as part of the carbon cycle (the process in which carbon dioxide is exchanged between the atmosphere, oceans, soil, plants, and animals). According to the EPA, since the industrial revolution, humans have altered the carbon cycle through activities like burning fossil fuels, which adds CO2 to the cycle, and deforestation which reduces natural ways in which CO2 is removed.
The increase in greenhouse gases, like CO2, trap heat in the atmosphere and contribute to global climate change. The pie-chart from the EPA shows a breakdown of the sources of carbon emissions in the United States. Other major greenhouse gases are methane and nitrous oxide.
PocketLab Air is an all-in-one science lab for investigating climate change and air pollution in your environment. PocketLab Air can measure carbon dioxide, as well as particulate matter (PM1, PM2.5, PM10), ozone, weather conditions, and can calculate the Air Quality Index. Using your phone's GPS, you can also map your data using your geo-location.
How Does the CO2 Sensor Work?
The carbon dioxide (CO2) sensor uses non-dispersive infrared (NDIR) radiation to measure the concentration of CO2 in the air. The sensor operates through the following method:
- An infrared light emitting diode (IR LED) emits light at a wavelength of 4.26 um.
- The IR light passes through the air and hits CO2 molecules which absorb that specific wavelength of light.
- The light absorption causes vibrations of the CO2 molecular bonds and reduces the amount of IR light that passes through the air.
- An infrared (IR) detector, also called a photodiode, detects how much IR light passed through the air sample.
- An optical filter covers the detector to only allow light with 4.26 um wavelength to pass through.
- The IR detector is calibrated to a known CO2 concentration in a laboratory and the data is stored in the sensor memory.
Measure your own respiration:
Exhale your breath toward the front of your PocketLab Air while measuring Carbon Dioxide. What do you notice?
Inside the cells in your body, when glucose (from the food you eat) reacts with oxygen (from the air you breathe), producing carbon dioxide, water, and energy. You use the energy and exhale the carbon dioxide.
Cellular respiration in yeast:
Yeast, a common fungus, is an ingredient often used in baking. When yeast is active in warm water, it can convert sugar into carbon dioxide through cellular respiration.
- Mix warm water with a tablespoon of yeast in a small dish.
- Place the list next to the PocketLab Air in a larger container that can be sealed.
- Add a tablespoon of sugar to the mixture of yeast and water and seal the large container.
- Record CO2 measurements and observe the yeast and sugar mixture.
As the yeast consumes the sugar the mixture will react and foam. What do you notice in the CO2 graph? Why?
Cellular respiration in seeds:
- Germinate lima beans by placing them in water and leaving them in a dark room for 24 hours.
- Place the germinated lima beans and your PocketLab Air inside a container.
- Seal the container.
- Record CO2 data with your PocketLab Air.
- Repeat the process with seeds that are not germinated.
- What do you notice?
Photosynthesis in a Terrarium:
- Build a terrarium by filling a large clear container with soil and a live plant.
- Place the PocketLab Air in the terrarium (to keep it free from the soil, use a tripod attachment or tape it to the inside of the terrarium).
- Place the terrarium in a sunny area.
- Record weather and CO2 data over time.
- What do you notice over the course of 24 hours? Specifically, how does the data change during the day compared to during the night? What does the data tell you about sunlight and plants?
For more environmental science lessons, using PocketLab Air, click here.
Citizen Science Investigation
There are many ways in which humans have added CO2 to the carbon cycle. Using your PocketLab Air, investigate what areas in your neighborhood emit high amounts of CO2.
Hint: Transportation accounts for 34% of carbon emissions in the US. A high traffic area might be a good place to start. Make sure you are being safe around traffic and always stay on the sidewalk.
A Carbon Sink is a natural or human-made reservoir that can accumulate carbon from the atmosphere and store it for a period of time. Trees and other plants are natural carbon sinks through the process of photosynthesis.
After finding areas in your neighborhood that emit high amounts of CO2, consider how Carbon Sinks could be better implemented in your community to combat climate change?