The carbon cycle and energy security EQ1 Flashcards
(36 cards)
What does carbon moving between the carbon pathway refer to?
Carbon existing in gas, liquid and solid forms and biotic and abiotic forms.
Why has the balance of atmospheric gases changed over geological time?
Because of Earth’s changing systems and processes.
What happened to the atmosphere during the Precambrian period?
Volcanic activity added carbon dioxide, water and sulphur dioxide to the atmosphere at an exponential rate.
What happened when primitive bacteria such as cyanobacteria started photosynthesising 3 billion years ago?
Oxygen was added to the atmosphere, while carbon dioxide was absorbed from it.
More complex organisms developed, due to higher oxygen levels.
How is limestone formed by marine organisms?
Calcium carbonate.
Marine phytoplankton absorb carbon through photosynthesis.
Remains accumulate on the seabed.
Over time, this is compacted to form limestone rock.
How else is limestone formed?
Direct precipitation of calcium carbonate from salt/freshwater.
Evaporation of sea water, which leaves behind calcium carbonate deposits.
What happens to carbon during chemical weathering?
Rain falls through the air - becomes a carbonic acid.
Dissolves calcium carbonate.
Erosion processes transfer dissolved carbon, forming deposits on the seabed, eventually forming new rock.
What is the first stage in the formation of coal?
The highest temperatures/pressures concentrate carbon to produce anthracite, which has a high energy potential. Source material must contain 2 per cent of organic carbon for this to happen.
What percentage of source material must organic carbon contain for carbon to produce anthracite?
2%.
What is the second stage in the formation of coal?
Anaerobic reactions convert over 90 per cent of organic carbon into crude oil.
What happens to the crude oil in the formation of coal?
Crude oil moves into permeable and porous rock layers, due to low density.
Becomes trapped within anticlines of impermeable rock.
What is an anticline?
Upfold of impermeable rock.
What percentage of carbon, and what percentage of hydrogen does crude oil contain?
85% carbon.
13% hydrogen.
How is methane created?
Created during coal and oil formation - trapped within the sedimentary rock layers.
What does diagenesis refer to?
The long-term process where sediments are changed into sedimentary rocks.
How do tectonic forces release carbon into the atmosphere?
Carbon-rich sedimentary rocks come into contact with extreme heat, which causes chemical changes and the release of carbon dioxide into the atmosphere.
How many million tonnes of carbon dioxide does volcanic activity release?
300 million tonnes every year.
Why is carbon dioxide the most common volcanic gas?
Least soluble - is degassed earlier in eruptions.
What happens to carbon at subduction zones?
Carbon dioxide is released at shallow crustal depth.
Why is Mount Etna in Italy the most actively degassing volcano in Europe?
Because of limestone and dolomite rocks from Tethys Ocean underneath.
What does the biological carbon pump refer to?
Carbon entering the food web via other organisms that use carbon to make their shells and skeletons (calcium carbonate).
Which type of water holds more gas; cold/deep water or warm/shallow water?
Cold/deep water. Slow-moving deep ocean currents hold carbon dioxide.
Explain why the Southern Ocean may not be such an effective carbon sink in the future.
Deep water rises very gradually to the surface, where it absorbs carbon dioxide from the atmosphere.
What is the role of large gyres?
Moving warm tropical water towards the poles, and colder water towards the equator.
