The carbon cycle

Question 1

Name the 4 stores carbon is present in

Answer 1

-atmosphere; (as Co2, methane)

-hydrosphere (dissolved CO2)

-lithosphere (as carbonate in limestones, chalk and fossil fuels,)

-biosphere (as carbon atoms in living & dead organisms)

Question 2

What is the carbon cycle

Answer 2

biogeochemical cycle which carbon moves from one sphere to another

-acts as a closed system

Question 3

What are fluxes

Answer 3

movements of organic compounds through an ecosystem

Question 4

Name the 2 components that make up the carbon cycle

Answer 4

-stores

-flows/ fluxes

Question 5

What are the organic stores and inorganic stores within the lithosphere store

Answer 5

organic stores -> litter, organic matter, humic substances found in soil

inorganic stores -> coal, oil, natural gas, oil shale, carbonate-based

Question 6

What are the stores within the hydrosphere

Answer 6

oceanic stores;
-surface layer (euphotic zone) - 900 GtC
-intermediate (twilight zone) & deep ocean layer
-living organic matter - 30 GtC
-dissolved organic matter - 700 GtC

Question 7

Name the 3 states carbon exists in

Answer 7

-gas
-organic
-inorganic

Question 8

What are carbon fluxes measured in

Answer 8

petagrams or gigatonnes of carbon per year.

Question 9

What does the carbon cycle show

Answer 9

how carbon moves from atmopshere through animas, plants & back into atmosphere

Question 10

Name the 8 main processes (fluxes) which carbon is transferred around natural states

Answer 10

-weathering
-respiration
-precipitation
-decomposition
-volcanic eruptions
-photosynthesis
-combustion
-oceans

Question 11

Precipitation and weathering

Answer 11

CO2 reacts with moisture in atmosphere to form weak carbonic acid

-carbonation (form of chemical weathering) -> when carbonic acid falls as rain it reacts with calcium carbonate rocks (sedimentary) & dissolves them

-transfers carbon from lithosphere to oceans

Question 12

Photosynthesis and respiration

Question 13

photosynthesis equation

Answer 13

co2 + water -> oxygen & glucose

Question 14

respiration equation

Answer 14

glucose + oxygen -> co2 + water

Question 15

Decomposition

Answer 15

decomposers break down complex cells and tissues of plants and animals into large biomolecules and then eventually individual atoms

-speed of decomposition is affected by vegetation (deciduous trees)

Question 16

Biomass combustion

Answer 16

combustion of biomass is the burning of living or dead vegattation

Question 17

volcanic activity

Answer 17

pockets of carbon dioxide exist in the Earth’s crust. Volcanic eruptions and earthquakes can release these gas pockets. Outgassing is the release of gas, previously dissolved, trapped, frozen or absorbed in some material (e.g. rock). It occurs mainly along mid-ocean ridges, subduction zones and at magma hotspots

-subaerial and submarine volcanic eruptions release CO2 from within the earths lithosphere

Question 18

oceans

Answer 18

cold oceanic water can hold co2 better than warm ocean water

-cold water sinks (downdwelling) and warm water rises (upwelling) therefore you have vertical mixing of water

-co2 dissolves in the oceans from the air by diffusion, it is moved around within a giant carbon pump

-this is called the physical (inorganic pump)

Question 19

Name the 3 types of oceanic caerbon pump

Answer 19

-biological pump ->

-physical pump

-carbonate pump

Question 20

What is phytoplankton

Answer 20

microscopic plants and plant-like organisms drifting or floating in the sea/freshwater along with diatoms, protozoa and small crustaceans.

Question 21

Explain the carbon cycle

Answer 21

carbon enters atmosphere as CO2 from respiration & combustion

-CO2 is absorbed by producers to make carbohydrates in photosynthesis

-animals feed on plant passing carbon compounds along food chain

-when animals and plants die -> dead organisms are eaten by decomposers & carbon in their bodies is returned to atmosphere as carbon dioxide

Question 22

What is a carbon sink

Answer 22

store of carbon which takes greater amount of carbon in than ouit

Question 23

What is a carbon source

Answer 23

store of carbon where amount of carbon leaving the store is greater than input

Question 24

What is sequestering

Answer 24

natural storage of carbon by physical/ biological processes such as photosynthesis

Question 25

Name the 5 key processes in the carbon cycle

Answer 25

-mechanical, chemical, biological weathering -decomposition -transportation -sedimentation -metamorphosis

Question 26

Explain mechanical weathering in the carbon cycle

Answer 26

-breakup of rocks by frost; shattering & exfoliation produces small, easy-to-transport particles

Question 27

Explain chemical weathering in the carbon cycle

Answer 27

-breakdown of rocks by carbonic aci in rain -> dissolves carbonate-based rocks

Question 28

Explain biological weathering in the carbon cycle

Answer 28

-burrowing animals and the roots of plants can break rocks up

Question 29

Explain decomposition in the carbon cycle

Answer 29

plant & animal particles that result from decomposition after death and surface erosion store carbon

Question 30

Geological origins

Answer 30

-carbon in limestone and shale -carbon in fossil fuels

Question 31

carbon in limestone and shale

Question 32

carbon fossil fuels

Question 33

Describe the process of chemical weathering

Answer 33

-water reatcs with atmospheric co2 -> carbonic acid -this water reaches the surface as rain reacting with surface minerals, dissolving them -calcium ions transported by rivers from land -> oceans, combine with bicarbonate ions to form calcium carbonate & precipitate out as minerals such as calcite -deposition & burial turns calcite sediment into limestone -subduction of sea floor under continental margins by tectonic spreading -this carbon rises back up and reenters atmosphere as co2

Question 34

What is volcanic outgassing

Answer 34

when pockets of co2 that exist in earth's crust are disturbed by eruptions/ earthquakes -> pulses/ more diffuse fluxes into the atmosphere

Question 35

Name 3 situations where oitgassing occurs

Answer 35

-active/ passive volcanic zones -places with no current volcanic activity -direct emissions from fractures in the Earth's crust

Question 36

oceanic sequestering

Question 37

What is the carbon cycle pump

Answer 37

processes operating in oceans to circulate & store carbon -theres 3 types; biological, carbonate, physical

Question 38

What is the thermohaline circulation

Answer 38

he global system of surface and deep ocean currents driven by temperature and salinity differences between different parts of the ocean

Question 39

Name the 3 types of oceanic carbon pump

Answer 39

-biological pumps -physical pumps -carbonate pumps

Question 40

Explain the biological pumps

Answer 40

-they move co2 from ocean surface to marine plants (phytoplankton) through photosynthesis -this converts co2 into food for zooplankton (microscopic animals) & their predators -these release co2 back into water & atmosphere

Question 41

Explain the carbonate pump

Question 42

Explain the physical pump

Answer 42

move carbon compounds to dif parts of ocean in downwelling & upwelling currents Downwelling occurs in parts of the ocean where cold, denser water sinks. These currents bring dissolved co2 down to deep ocean. Once there, it moves in slow-moving deep ocean currents, staying there for hundreds of years. Eventually, these deep ocean currents, part of the thermohaline circulation, return to the surface by upwelling. The cold deep ocean water warms as it rises towards the ocean surface and some of the dissolved carbon dioxide is released back into the atmosphere. -colder the water, the higher the potential for co2 to be absorbed

Question 43

Explain what occurs in the terrestrial sequestering

Answer 43

plants sequester carbon out of atmosphere during photosynthesis -carbon then enters food chains & nutrients cycles of terrestrial ecosystems -when amilas consume plant matter -> carbon in plant becomes part of their fat & protein -respiration by consumer animals returns carbon back to atmosphere -waste from animals -> eaten by micro-organisms, detritus feeders -when they die -> remains fall to ground -> carbons released into soil

Question 44

Carbon fluxes within ecosystems vary on 2 timescales -what are these 2 timescales

Answer 44

-diurnally; during day fluxes are positive, from atmosphere to ecosystem -at night flux is negative -> loss from ecosystem to atmosphere -> due to rspiration not photosynthesis occuring -seasonally; winter -> co2 increases -> low levels of plant growth -in spring plants grow -> co2 decreases until autumn.

Question 45

Explain primary producers and consumers within terrestrial stores

Answer 45

primary producers -> green plants -> co2 absorbed & convetred into new plant growth during photosynthesis -as plants grow -> release co2 -> atmosphere -> through respiration -primary consumers -> bugs, beetles, herbivores -> feed on producers -> return carbon to atmosphere during respiration