The Carbon Cycle

Carbon is an essential element for life on earth. It is found in the atmosphere, the water, the soil, and in living things. Places where carbon is found are called carbon reservoirs. Carbon takes many forms and moves from one reservoir to another in a series of biological and chemical processes known as the carbon cycle.

Carbon is found in the atmosphere in the form of carbon dioxide (CO 2 ) CO 2 disperses the suns energy keeping the atmosphere warm Originally most of the CO 2 in the atmosphere was released from volcanoes Today, most of the CO 2 in our atmosphere is released by burning fossil fuels (coal, oil, and natural gas)

Many of the molecules that make up plant cells contain carbon Plants take CO 2 from the atmosphere in a process called photosynthesis 6CO 2 + 6H 2 O + Energy --> C 6 H 12 O 6 + 6O 2 CO 2, water, and sunlight are used to make glucose (sugar) and oxygen

Many of the molecules that make up animal cells contain carbon Animals obtain carbon by eating plants and other animals animals produce carbon dioxide in a process called cellular respiration C 6 H 12 O 6 + 6O 2 --> 6CO 2 + 6H 2 O + Energy Glucose and oxygen are used by the body to make CO 2, water, and energy

CO 2 is absorbed at the ocean’s surface and used by photosynthetic algae Carbon moves up the food chain when small animals eat algae and larger animals eat smaller animals When animals die and sink to the bottom of the ocean, carbon is brought down to the deep ocean

Carbon enters soil when plants an animals die and are broken down by insects, bacteria, and fungi in the soil Some CO 2 is absorbed by plants for photosynthesis Some CO 2 turns into fossil fuels over millions of years

Carbon remains stored in fossil fuels until the fuels are burned for energy Burning fossil fuels in automobiles and electric generators releases CO 2 into the atmosphere Coal, oil, and natural gas are all examples of fossil fuels They form out of the buried remains of plants and animals over millions of years