THE CARBON CYCLE

What Is Carbon? An element The basis of life of earth Found in rocks, oceans, atmosphere

Carbon Cycle The same carbon atoms are used repeatedly on earth. They cycle between the earth and the atmosphere.

Inorganic Carbon Carbon exists in the nonliving environment as: Carbon dioxide (CO2) Carbonic acid ( HCO 3 − ) Carbonate rocks (limestone and coral = CaCO 3 ) Deposits of Fossil fuels Dead organic matter

Organic Carbon Hydrocarbons: CH 4 Carbohydrate: CH 2 O

Carbon reservoirs

The atmosphere. (CO2) The biosphere (include fresh water systems and non-living organic material, such as soil carbon) The oceans (including dissolved inorganic carbon and living and non- living marine biota) The lithosphere (sediments, Earth core including fossil fuels)

Carbon Cycle

Carbon is released into the atmosphere in several ways Respiration by plants and animals. Decay of animal and plant matter. Combustion of organic material Production of cement. The ocean releases CO2 into the atmosphere. Volcanic eruptions and metamorphism

Carbon is taken from the atmosphere in several ways Photosynthesis. The oceans when the seawater becomes cooler, more CO 2 dissolve and become carbonic acid. In the upper ocean areas organisms convert reduced carbon to tissues, or carbonates.

Photosynthesis CO 2 + H 2 O + sunlight  CH 2 O + O 2

Plants Use Carbon Dioxide Plants pull carbon dioxide from the atmosphere and use it to make sugars through photosynthesis. The carbon becomes part of the plant (stored food).

Animals Eat Plants When organisms eat plants, they take in the carbon and some of it becomes part of their own bodies.

Respiration CH 2 O + O 2  CO 2 + H 2 O + energy Done by plants and animals

Combustion or Oxidization of hydrocarbon CH O 2  CO H 2 O + energy

Plants and Animal Die When plants and animals die, most of their bodies are decomposed and carbon atoms are returned to the atmosphere. Some are not decomposed fully and end up in deposits underground (oil, coal, etc.).

Carbon Slowly Returns to Atmosphere Carbon in rocks and underground deposits is released very slowly into the atmosphere. This process takes many years.

Carbon in Oceans Additional carbon is stored in the ocean. Many animals pull carbon from water to use in shells, etc. Animals die and carbon substances are deposited at the bottom of the ocean. Oceans contain earth’s largest store of carbon.

Cycle – Repeats Over and Over and Over and Over …

Carbon Cycle Diagram Carbon in Atmosphere Plants use carbon to make food Animals eat plants and take in carbon Plants and animals die Decomposers break down dead things, releasing carbon to atmosphere and soil Bodies not decomposed — after many years, become part of oil or coal deposits Fossil fuels are burned; carbon is returned to atmosphere Carbon slowly released from these substances returns to atmosphere