The Carbon Cycle

Earth-Space ScienceThe Geosphere Lesson 02

The Carbon Cycle

By the end of this lesson you should be able to:

• Discuss the steps of the carbon cycle• Analyze movement of matter and energy

through the carbon cycle• Discuss interactions of the carbon cycle with

all spheres of Earth (hydrosphere, cryosphere, geosphere, biosphere & atmosphere)

Carbon and Carbon Dioxide• Carbon – the 6th most abundant

element in the universe. – Some examples: Coal, Graphite, Diamonds

• Carbon Dioxide– Two (di) oxygen atoms bonded to one

Carbon – often written as CO2

– A trace gas, crucial in photosynthesis when plants take in CO2 and release O2

6 CO2 + 6 H2O → C6H12O6 + 6 O2

Carbon dioxide + Water + Light energy → Glucose + Oxygen

How does the carbon cycle impact Earth's spheres?Biosphere – Includes all living things on Earth, such as plants and animals.

Geosphere – The land surfaces and interior of the Earth.

Hydrosphere – All of the water in the Earth’s oceans lakes, rivers and streams.

Atmosphere – The thin layer of gas surrounding the Earth

Cryosphere – All of the ice on Earth such as glaciers and the icecaps.

Exosphere- Everything located outside of the Earth, including stars and galaxies.

Earth Cycles• Essential element: A chemical element from the periodic table

that is necessary for life processes on Earth

• Biogeochemical cycles: The essential elements move through cycles in the Earth system, taken up by living organisms (Biosphere) and then returning to one of the Earth’s spheres after the organisms die, and eventually are taken up by living organisms.

• Conservation of Matter Review – Matter cannot be created or destroyed (from BWS)

• The Carbon Cycle : The carbon cycle is the movement of carbon between the biosphere and the other nonliving spheres of Earth. Smaller cycles exist within the main Carbon Cycle. And we will look at those now…

Carbon Dioxide CO2 Where is it?

+ CO2 is held in surface water as a dissolved gas

+ Dead and decaying plants and animals release CO2

+ CO2 is released by factories and people burning fossil fuels

+ CO2 is exhaled by living creatures during respiration

+ CO2 is held in the atmosphere as a trace gas

+ Trees use CO2 to make food and give off oxygen. Deforestation leads to higher CO2 levels.

Photosynthesis & Respiration

Short Term Carbon CycleA product of the carbon cycle is oxygen, when the

process of photosynthesis takes carbon from the atmosphere and stores it in the plant as sugar that can be used as a source of energy.

Oxygen released from plants is then exchanged in the lungs of animals during the process of respiration

One of the products of the process of respiration is carbon dioxide (CO2), which is released back into the atmosphere.

Animals release the carbon in the food molecules back to the geosphere through the process of excretion. Plants and animals also release stored carbon through the process of death/decomposition.

Carbon is released by other organisms, known as decomposers, which break down waste material. The carbon becomes a part of the geosphere or hydrosphere once again.

What are Fossil Fuels?

• Living creatures on Earth are Carbon based• Dead organisms (mostly plants) become

buried, metamorphose (heat and pressure)• Burning of fossil fuels releases the trapped

Carbon• Considered Non-Renewable because it takes

millions of years for the metamorphism to occur – Used much faster than produced

Long Term Carbon CycleA Geologic Process

• Carbon is stored in rocks, soils, and fossil fuels, and is also released through volcanic eruptions

• Fossil Fuels include – Coal, Oil, and Natural Gas and can be burned for energy, releasing CO2

• Combustion (burning) of plant matter (leaves etc) also releases CO2 to the atmosphere

• Deforestation removes plants therefore they can no longer remove CO2 from the atmosphere

Long Term Carbon CycleDiffusion

• Can you smell your perfume as well at the end of the day as you can at the start?

• Diffusion – substances move from high concentration to low concentration

• Gaseous CO2 is dissolved in the ocean in large amounts and will diffuse to the atmosphere

• Rain can pick up CO2 from the atmosphere producing acid rain

• Takes CO2 back to the Earth, and hydrosphere

Long Term Carbon CycleBiosphere & Geosphere

• Some sea animals take CO2 from ocean water and secrete shells

• When the animals die, their shells fossilize, eventually break down, or weather/erode and release Carbon

• Shells, and excrement will all fall to the bottom of the water, leading to a higher Carbon content in deep water.

• Ocean currents circulate water and brings carbon to the surface

• Note that the blue boxes represent the products

• Other writing represents the process

What can YOU do?

Carbon footprint: "the total set of greenhouse gas (GHG) emissions caused by an organization, event, product or person.".

http://timeforchange.org