Carbon Flashcards
what is the fast/biological carbon cycle
the movement of carbon from living things up into the atmosphere
What processes occur in the fast/biological carbon cycle
- photosynthesis
- respiration
- digestion
- decomposition
- combustion
- gas exchange
what is digestion
the release of carbon compounds by terrestrial and marine animals after feeding on carbon-rich materials
what is decomposition
the breakdown of animals and plant structures by bacteria, and the release of carbon compounds into the atmosphere, soil, and to the ocean floor
what is released in decomposition
- CO2 when oxygen is present
- CH4 when oxygen is absent
what is gas exhange
the mutual transfer of CO2 between the lower atmosphere and ocean surfaces
what are key features of the terrestrial carbon cycle
- dominated by photosynthesis
- carbon stored in biomass
- part of the fast carbon cycle
- bacteria in decomposition releases CO2
How is carbon transferred to the soil in the terrestrial carbon cycle
leaf litter, roots, and plant debris upon decomposition
What are the human impacts on the terrestrial carbon cycle
- urbanisation and deforestation affect the biomass and carbon exchange between soil and atmosphere
- clearing vegetation through combustion
what are the key features of the marine carbon cycle
- carbon stored as dissolved CO2, bicarbonate ions in solution, tissue of marine organisms
- phytoplankton perform photosynthesis and are eaten by zooplankton
what are the human impacts on the marine carbon cycle
warmer oceans = less CO2 absorption from atmosphere = reduction in phytoplankton activity
What are the key features of the carbon cycle in the atmosphere
- usually in the form of CO2 or CH4
- carbonic acid, formed when CO2 combines with H2O in clouds
- acid rain contributes to weathering and ocean acidification
What natural factors are causing an increase in atmospheric CO2
- periods of increased volcanicity
- glacial periods mean less vegetation
- interglacial periods cause warmer oceans
- winter in the north shuts down biomass
What natural factors are causing a reduction in atmospheric CO2
- long-term reduciton of volcanicity
- glacial periods create cooler oceans
- interglacial periods have more vegetation
- summers in the Northern Hemisphere have increased biomass activity
What human factors are causing an increase in atmospheric CO2
- burning fossil fuels
- causing more wildfires
- an increasing meat-based diet
- melting tundra releasing CO2 and CH4
- clearing natural vegetation for urban/agricultural/industrial use
What human factors are causing a reduction in atmospheric CO2
- CCS schemes
- re/afforestation projects
what is combustion
natural fires release carbon compounds from vegetation to the atmosphere
What happens in stage 1 of the slow/geological carbon cycle: the transfer of CO2 into the oceans from the atmosphere and land surface
carbonic acid rain dissolves surface rocks and transfers soluble bicarbonate compounds to the sea via rivers
What happens in stage 2 of the slow/geological carbon cycle: the deposition of carbon compunds on the ocean floor
- marine plants absorb CO2, while marine animals take in carbon to construct skeletons and shells
- phytoplankton are eaten by zooplankton and carbon-rich excrement falls to the ocean floor
- skeletal and shell remains of marine animals fall to ocean floor
What happens in stage 3 of the slow/geological carbon cycle: the conversion of ocean sediments into carbon-rich rock
- carbon-rich accumulations of deposits may be converted into carbon-rich rocks or become contained as concentrations in sandstones and shales to form organic deposits (lithification) (some become fossil-fuel reserves)
What happens in stage 4 of the slow/geological carbon cycle: the transfer of carbon rocks to tectonic margins
- as sedimentary rocks move in the direction their crustal plate is moving
- if they end up at collision margins, they may be uplifted to become surface mountain ranges
- carbon rich strata may be exposed to weathering (restarting the cycle)
What happens in stage 5 of the slow/geological carbon cycle: the return of carbon compounds to the atmosphere in volcanic eruptions
if carbon-rich rocks move near subduction zones, they could be ejected by volcanic eruptions
What is the physical carbon pump
when carbon compounds are transported to different parts of the ocean through downwelling and upwelling currents
How does CO2 enter the ocean carbon cycle once it is dissolved in surface sea water
- physical carbon pump
- biological carbon pump
- carbonate carbon pump
What role does downwelling play in the physical carbon pump
- downwelling currents bring dissolved CO2 to the deep ocean
- moves into slow-moving deep ocean currents (usually staying there for a hundred years)
What role does upwelling play in the physical carbon pump
- upwelling currents bring deep, cold ocean water to the surface
- when the water warms, some of the CO2 is released back into the atmosphere
what is the biological carbon pump
- driven by marine organisms
- all about photosynthesis, respiration, eating, excreting, and decomposing
What does the biological carbon pump play a major role in
- transforming carbon compounds into new forms
- moving carbon throughout the ocean
- moving carbon down to sea floor sediments
how are phytoplankton important for the biological carbon pump
- photosynthesize and produces carbon compounds
- brings carbon compounds into the marine food web
- some carbon ends up in deep ocean currents and seafloor sediments
- return CO2 and O2 to the atmosphere via respiration
What is the ocean carbonate pump essential to
shell building marine organisms like coral, oysters, clams, pteropods, sea urchins, some forms of planktons, and lobsters
What is the ocean carbonate pump linked to
- the biological carbon pump
- plays a big role in transporting carbon down to deep ocean sediments
What chemical compounds are produced through reversible reactions in the ocean carbonate pump when CO2 combines with water molecules
- bicarbonate ions
- hydrogen ions
- carbonate ions
why are carbonate ions especially important to marine organisms
combine with calcium ions to form calcium carbonate which are used to build shells, plates, and inner skeletons
What happens when shell builders die
- the carbon in their shells is transported to the deep ocean
- becoming part of the deep ocean currents and sea floor sediments
- as most shells dissolve before reaching the seafloor sediments, CO2 is released into the deep ocean currents
what happens to shells that don’t dissolve before reaching deep ocean sediments
slowly build up and form calcium carbonate sediments
how are calcium carbonate (CaCO3) sediments transformed into limestone
lithification (this locks massive amounts of carbon away for millions of years)
What are the two major types of soil carbon
- biomass (living bacteria and fungi)
- non-biomass carbon (cellulose, starch, and lignin in dead plants)
What happens when soils lose their carbon
become degraded and unable to provide nutrients to support plant growth and biodiversity
What are the benefits of improving the soil’s ability to capture and retain carbon
- contributes to mitigation and adaptation to climate change
- makes land more suitable to sustain biodiversity
- preserve food security
what is carbon sequestration
the process of using and storing carbon