Carbon and energy Flashcards
(256 cards)
What are the 3 carbon stores?
Inorganic (in rock as bicarbonate/carbonate)
Organic (in plant material)
Gaseous (eg: CO2, CH4, CO)
What are the 2 biggest stores of carbon?
Marine sediments + sedimentary rock (100 mil Gt)
Ocean (40,000 Gt)
What are some medium sized stores of carbon?
Fossil fuels
Soil organic matter
Permafrost/ice
What are the 2 smallest stores of carbon?
Atmosphere + terrestrial plants
What are 8 fluxes in the carbon cycle?
Burning fossil fuels
Plant/soil respiration
Photosynthesis
Volcanoes
Litterfall
Rivers
Deforestation/land use change
Ocean uptake/loss
What is the role of latitude in flux speed of CO2?
Levels of photosynthesis + respiration greater in northern hemisphere as greater landmass, greater temperature variations
What is the geological carbon cycle?
Slowest part of the carbon cycle (millions of years)
What are the 5 steps to the geological carbon cycle?
- Mechanical + chemical + biological weathering
- Decomposition of carbon-storing plants and animals
- Rivers carry particles to ocean where deposited
- Sediments accumulate, burying older sediments below (shale/limestone)
- Metamorphosis, layering builds pressure so deeper sediment -> rock eg: shale -> slate. limestone -> marble, volcanoes release CO2 to atmosphere
What are the 3 key processes in the geological carbon cycle?
Chemical weathering
Fossil fuel formation
Volcanic outgassing
How does chemical weathering play a role in the geological carbon cycle?
H2O + CO2 -> carbonic acid, which dissolves rock into calcium ions
Ions transported by river to ocean, where combines with bicarbonate ions and carbonates
Precipitates out as minerals eg: calcite, which turns to limestone via deposition and burial
Then subducted at plate margins, outgassed by tectonic activity
How does fossil fuel formation play a role in the geological carbon cycle?
Gas + oil: 300 mil years ago dead organisms sank to ocean floor, buried deeper + changed to kerogen under heat + pressure + no oxygen, generates oil/gas over millions of years
Coal: remains of plants covered 100 mil years ago, forms peat, eventually solidified into coal
How does volcanic outgassing play a role in the geological carbon cycle?
Outgassing of CO2 from pockets in crust at subduction zone with extreme tectonic pressure
Degassing of CO2 from magma at divergent hotspots/geysers
-> eruptions return CO2 to atmosphere (negative feedback)
What is the speed of the oceanic carbon pump?
Much faster
What does phytoplankton do?
Account for half of all photosynthetic activity
Lives at well-lit surface of water
Sequesters (removes and stores) atmospheric carbon
What are the 3 types of oceanic carbon pump?
Biological carbonate pump
Carbonate pump
Physical pump: thermohaline circulation
How does the biological carbonate pump work in the carbon cycle?
Phytoplankton sequester 2Gt of CO2 to ocean /y
At base of food chain, so consumed by other marine organisms who respire, returning CO2 to water + atmosphere
How does the carbonate pump work in the carbon cycle?
Calcium carbonate shells/skeleton sinks to ocean floor,building up seabed (sedimentary rock)
Subducted + emitted via volcanoes as part of geological carbon cycle (creates global carbon equilibrium)
What is both the biological carbonate pump and the carbonate pump reliant on?
Mainitainence of ocean temperature + currents + recycling of nutrients
How does the physical pump/thermohaline work in the carbon cycle?
Global system of surface/deep ocean currents driven by temperature/salinity differences
Downwelling results in cold, dense water sinking at poles. bringing dissolved CO2 to slow, deep ocean current for hundreds of years
Returns to surface by upwelling and warmer water rises at equator, holding less CO2 -> some dissolved CO2 returns to atmosphere
What are terrestrial primary producers?
Land-based green plants that use solar energy to produce biomass
What are 3 differences in terrestrial carbon stores?
Forest biomes hold most global carbon (1146 Gt)
Then temperate grassland, tropical savannah
More stores in soil than vegetation
How does temperature affect net primary productivity?
Higher temp = high NPP as high rate of photosynthesis
What are the 3 carbon terrestrial fluxes?
Diurnal (more sequestration in day)
Seasonal (more sequestration summer)
Anthropogenic (forest burning releases carbon)
What is soil?
Thin surface of the crust containing organic and inorganic matter