14 - Fast and Slow Carbon Cycle Pumps Flashcards
What are the two “pumps” that move carbon between the ocean and atmosphere?
The biological pump and the physical pump
Draw a diagram of the fast carbon cycle?
What is the Physical(inorganic pump)?
- Involves the mixing of surface and deep ocean waters by vertical currents, creating a more even distribution of carbon both geographically and vertically in the oceans.
What is the Biological (organic) pump?
- The ocean’s biologically driven sequestration of carbon from the atmosphere to deep sea water and sediment.
Stat about the biological pump
- 50 GT of C02 a year is sequestered by the biological pump
How much carbon does the fast cycle move compared to the slow cycle?
- The fast carbon cycle involves around 1,000 to 100,000 million metric tons of carbon a year
- The slow carbon cycle moves between 10 and 100million tonnes of carbon a year and as it involves the lithosphere, the carbon moves more slowly between stores.
Timings for Slow Carbon Cycle
- 100-200 million years
Draw a diagram of the slow carbon cycle
What is Carbon Sequestration?
- Carbon sequestration is the process of capturing and storing atmospheric C02 in other stores
- i.e. forests, soil, oceans, geological formations
Stat
How much more C02 does the Ocean hold more than the atmosphere?
The ocean holds 50 times more C02 than the atmosphere
Describe the biological pump
- The surface of the ocean absorbs carbon dioxide from atmosphere via process of diffusion
- Phytoplankton use this dissolved carbon dioxide for food and to build their structures; bodies; skeletons (i.e. organic carbon compounds)
- Phytoplankton is part of a food chain and they are eaten by other organisms. This means carbon gets passed down the food chain as other marine creatures consume the carbon compounds
- All the living organisms in food chain respire and so release carbon dioxide back into the ocean
- When the organisms die their remains (full of carbon compounds) sink to the ocean floor and accumulate to form carbon-rich sediments
- Also as the dead organisms sink, their remains are attacked by bacteria and decompose, which releases CO2 into the deep ocean.
Stat
How much of the carbon absorbed from the atmosphere actually reaches bottom sediments?
Only about 1-2% of carbon absorbed from atmosphere reaches bottom sediments
Describe the physical/solubility pump
- CO2 is dissolved in surface ocean by diffusion
- Surface currents & dissolved CO2 move water towards poles
- When the water gets close to poles the water cools, becomes more dense and therefore sinks. This is called downwelling.
Downwelling only occurs in certain places on earth - i.e. North Atlantic Ocean near Greenland and Iceland
- Cold water can hold a lot of carbon dioxide, so lots of CO2 transported from the surface ocean to the deep ocean. Some carbon can be trapped for centuries in deep ocean
- The carbon doesn’t just stay in the deep ocean forever eventually deep ocean currents will rise to the surface in the process of upwelling (i.e. Indian Ocean, Pacific Ocean)
- This means that CO2 that was previously in the deep ocean layer eventually is diffused back to the atmosphere
- Normally this happens in warmer areas like around the equator (i.e. Indian Ocean, Pacific Ocean)
- Warmer water can’t hold as much CO2 so more CO2 diffuses into the atmosphere
How do trees sequester carbon?
- Vegetation sequesters carbon through the process of photosynthesis, where trees absorb carbon dioxide from the atmosphere and convert it into organic compounds that are stored in various parts of the tree, including the leaves, stems, trunk, and roots
- However, since trees are living organisms, they also respire and release some carbon dioxide back into the atmosphere.
- When trees die, the carbon stored in their organic compounds will decompose and release carbon dioxide back into the atmosphere
- Some of the carbon molecules that are broken down during decomposition will make their way into the soil and be stored there.
