2.2 – The Carbon Cycle

Where is Carbon Stored?

Short Term Stores:Land and marine animals and plants and in

decaying organic matter. Atmosphere as CO2 and in the upper layer of the

ocean in its dissolved form. Long Term Stores:In water: Intermediate and deep depths of the

ocean as dissolved CO₂On land: coal, oil gas deposits (fossil fuels) dead

plants and animalsLargest stores are found in SEDIMENTARY ROCK

(eg: limestone) and marine sediments

SedimentationDecaying matter and soil particles begin to

form layers, eventually becoming rock

CarbonateCarbon/oxygen organisms containing calcium

carbonateBecomes limestone

How is Carbon Cycled Through the Ecosystems?

1. Photosynthesis2. Respiration3. Decomposition4. Ocean Processes 5. Volcanic eruptions and large scale forest

fires

1. Photosynthesis

Chemical process that cycles both C and O2 through ecosystems Coverts solar energy into chemical energy

CO2 in the atmosphere enters the leaves of plants and reacts with water in the presence of sunlight to produce carbohydrates (glucose) and O2 :

Consumers eat producers and obtain energy from them in the form of carbohydrates

Some micro-organisms such as cyanobacteria use photosynthesis, not just green plants for energy!

2. Cellular Respiration

Process where animals and plants (in the absence of light) release CO₂ into the atmosphere by converting O2 and glucose (C6H12O6) into CO₂ and water:

C6H12O6 + 6 O2 6CO2 + 6 H2O + energy

3. Decomposition

The breaking down of dead organic matterDecomposers include: bacteria, fungi,

insects, worms (aka Detrivores).They breakdown cellulose (plant matter)

and in the process convert it into CO2

4. Ocean Processes

Ocean currents and colder oceans found at high latitudes cause more carbon to be retained as it sinks deeper into the depths of the ocean.

These deeper carbon rich currents move slowly to the tropics where it gradually is warmed and is released back into the tropical atmosphere:

Carbon in the Ocean

5. Volcanic Eruptions and Forest Fires

Carbon dioxide is released from volcanoes due to the melting of sedimentary rock, a rich store of carbon into the atmosphere

Forest fires due to the rapid burning of trees releases carbon dioxide into the atmosphere.

6. Human Activities

Activities such as: industry, motorized transportation, land clearing, agriculture, urban expansion

Have a negative impact on the carbon cycleSince 1850 (industrial revolution) carbon

dioxide gas in the atmosphere has increased by 30%

We are producing more carbon than the natural carbon cycle can store it.