1.4 Carbon Cycle - APES

Carbon Cycle Overview

Movement of molecules that contain Carbon (CO₂, glucose, CH₄) between sources and sinks

Some steps are very quick (FF combustion) → Some are very slow (Sedimentation & burial)

Leads to an imbalance in which reservoirs or sinks are storing carbon

• Atmosphere is the key C reservoir: Increasing levels of C in atm. Leads to global warming

Carbon Sink: A carbon reservoir that stores more carbon than it releases

Carbon Source: Process that adds C to atm.

• FF (Oil, coal, natural gas) combustion

• Animal ag. (Cow burps & farts = CH₄)

• Deforestation releases CO₂ from trees

Photosynthesis

Removes CO₂ from the atmosphere & converts it to glucose 

• Glucose = Biological form of C & stored (chemical) energy in the form of sugar

• CO₂ sink

• Plants, algae, phytoplankton

Cellular Respiration 

Done by plats/animals to release stored energy

• Uses O₂ to break glucose down and release energy

• Releases CO₂ into atmosphere 

• CO₂ source (Adds CO₂ to atm.)

Ocean & Atmosphere

• Direct exchange: CO2 moves directly between atmosphere & the ocean by dissolving into & out of ocean water at the surface

Happens very quickly & in equal directions, balancing levels of CO2 between atm. & ocean

• B/c of direct exchange, increasing atm. CO2 also increases ocean CO2, leading to ocean acidification

• Algae & phytoplankton take CO2 out of the ocean & atm. through photosynthesis

  • Coral reef & marine org. with shells also take CO2 out of the ocean to make calcium carbonate exoskeletons

• Sedimentation: when marine org. die, their bodies sink to ocean floor where they’re broken down into sediments that contain C

• Burial: over, long, periods of time, pressure of water compresses C-containing sediments on ocean floor into sedimentary stone (limestone, sandstone) - long-term C reservoir

Burial, Extraction, & Combustion

Burial: Slow geological process that stores C in underground sinks like sedimentary rock/FF

• Sediments (bits of rock, soil, organic matter) compressed into sed. rock, or FF, by pressure from overlying rock layers or water

Fossil Fuel: Coal, oil, and natural gas are formed from fossilized remains of organic matter

Extraction & Combustion: Digging up or mining FFs & burning them as an energy source: Releases CO₂ into the atmosphere.

Burial (Formation of FF’s) takes far longer than extraction & combustion, which means they increase concentration of CO₂ in the atmosphere