The Carbon Cycle

By Moira Whitehouse PhD

• The characteristics of the remarkable carbon atom make possible the compounds that are necessary for life on Earth.

• Carbon is an element found throughout the universe.

• It is found in all living things and without carbon there would be no life on Earth.

• Carbon is also part of nonliving things such the oceans, rocks ,animal shells, and the atmosphere.

• Carbon atoms continually move through living things, the oceans, the atmosphere and the crust of the Earth.

• Carbon doesn’t just stay in one place however. It’s always on the move.

• This movement is known as the carbon cycle

Carbon dioxide, a gas in our atmosphere, is partly carbon and is an important part of the carbon cycle.

A carbon dioxide molecule is made up of one part carbon and two parts oxygen.

carbon

oxygen

http://cfs.nrcan.gc.ca

During photosynthesis, carbon dioxide is taken into the plant and changed into plant food. The carbon is then stored in this food. In this process of photosynthesis, oxygen is given off.

Carbon moves through its “cycle” in several ways, one way is by photosynthesis.

During respiration, animals take in oxygen and breathe out carbon dioxide.

Carbon on the move through respiration (breathing)

arthursclipart.org

In this diagram we see the exchange of the gases—carbon dioxide and oxygen between plants and animals.

Plants are the foundation of a food chain. The carbon that is stored in its food is passed down from one animal to another though this chain.

Here we see carbon on the move through the food chain.

That’s because when plants and animals die, their bodies decay and carbon dioxide is released into the air—carbon moves back into the air.

And here, carbon is being moved through decomposition.

Let’s review what we have studied so far.

Diagrams in the next four slides show how carbon moves in its cycle.

1. Carbon dioxide in the air moves to plants through photosynthesis

2. Carbon moves from plants to animals through the food chain

3. From live plants and animals (respiration) and burning fuel back into the atmosphere as carbon dioxide.

4. From dead plants and animals through decomposition back into the atmosphere as carbon dioxide.

http://www.kscience.co.uk/animations/carbon_cycle.htm

Here is a website with three choices which show the movement of carbon through the carbon cycle. Simply choose download and then select the process you wish to study.

Remember fossil fuels are our main source of energy.

We use fossil fuels to:

Now let’s look at how fossil fuels fit into the carbon cycle.

1. Power all our vehicles--cars, trucks, buses, trains, planes and tractors.

Steam

Often, coal or natural gas is burned to heat water. The water changes into steam which turns a turbine which then turns a coil of wire inside a magnet generating electricity.

2. Generate our electricity.

Large generators produce the electricity we use in our homes, schools and work places.

3. Power all the factories that make the things we use.

Do you remember how fossil fuels—crude oil, coal and natural gas—are formed?

Yes, they are formed from the remains of plants and animals.

The carbon from the dead plants and animals is stored in fossil fuel.

However, in order to use fossil fuels for energy, we must burn them.

And when they burn, carbon dioxide is given off and returned to the air—carbon on the move again.

Some of this carbon is cycled back through carbon dioxide to the plants particularly trees.

National Center for Atmospheric Research and UCAR

Can you follow carbon moving through the cycle in the diagram on the left.

The Carbon Cycle