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A Level Geography (OCR) > ELSS (Topic 2) > Flashcards

ELSS (Topic 2) Flashcards

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1
Q

What % of Earth’s surface is oceans?

A

71%

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2
Q

How do oceans moderate Earth’s environment? (3 ideas)

A
  1. Absorbing heat, storing it and releasing it slowly
  2. Clouds reflect 1/5 of solar radiation- lowers temperature (albedo effect)
  3. Water vapour absorbs long-wave radiation from the Earth- helps maintain global temps 15*C higher than would be
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3
Q

How do flora use water? (4 ideas)

A
  1. Manufacture own food so need water for: photosynthesis (combining CO2, sunlight & water = glucose and starches); respiration (converts glucose to energy through reaction with oxygen- release CO2 & water)
  2. Maintain rigidity- wilt when run out of water
  3. Transport mineral nutrients from the soil
  4. Cooling- transpiration of water from leaf surface cools plants by evaporation
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4
Q

How do fauna use water? (2 ideas)

A
  1. Water = the medium for all chemical reactions- i.e. circulation of oxygen and nutrients
  2. Evaporative cooling achieved through panting
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5
Q

How do humans use water? (3 ideas)

A
  1. Water = the medium for all chemical reactions- i.e. circulation of oxygen and nutrients
  2. Cooling- sweating
  3. Economic activity- generate electricity, irrigate crops, provide recreational facilities, satisfy public demand (drinking water, sewage disposal), industry (food manufacturing, brewing, steel making)
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6
Q

How is carbon stored? (5 ideas)

A
  1. Carbonate rocks (limestone)
  2. Sea floor sediments
  3. Ocean water (as dissolved CO2)
  4. Atmosphere (CO2 gas)
  5. Biosphere
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7
Q

How is life carbon based?

A

Built on large molecules of carbon- proteins, carbohydrates, nucleic acids

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8
Q

How can carbon be used as an economic resource? (3 ideas)

A
  1. Fossil fuels (coal, oil, natural gas) power the global economy
  2. Oil is used as a raw material in manufacturing of products (from plastics to paint and synthetic fabrics)
  3. Agricultural crops and forest trees store large amounts of carbon available for human use (i.e. food, timber, paper, textiles etc)
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9
Q

What is the atmosphere?

A
  • Envelope of gases surrounding the planet
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10
Q

What is the cryosphere?

A
  • Frozen part of the Earth’s surface
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11
Q

What is the lithosphere?

A

Rigid outer part of the Earth (upper mantle and crust)- divided into tectonic plates

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12
Q

What is hydrosphere?

A
  • All the water on the Earth’s surface
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13
Q

What is the biosphere?

A
  • Space at the Earth’s surface and within atmosphere occupied by living organisms
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14
Q

What is the pedosphere?

A
  • Soil layer of Earth
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15
Q

At a global scale, what are the 3 main stores of the water cycle?

A
  1. Oceans (biggest store)
  2. Atmosphere (smallest store)
  3. Land
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16
Q

What are the main processes by which water moves between the 3 stores? (4 ideas)

A
  1. Precipitation
  2. Evapotranspiration
  3. Run-off
  4. Groundwater flow (horizontal movement of water within aquifers)
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17
Q

What is the long-term storage of carbon AND what % does it hold of all carbon on Earth?

A

Sedimentary rocks

99.9%

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18
Q

What stores does the carbon in circulation move between? (4 ideas)

A
  1. Atmosphere
  2. Oceans
  3. Soil
  4. Biosphere
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19
Q

What are the main processes by which circling carbon moves between the stores? (4)

A
  1. Photosynthesis (atmosphere to terrestrial biomass)
  2. Respiration (terrestrial biomass to atmosphere)
  3. Oxidation (human activity- combustion to atmosphere; decomposition- terrestrial biomass to atmosphere; soil to atmosphere)
  4. Weathering (sedimentary rocks to atmosphere)
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20
Q

What is a large-scale, infrequent event which moves a large amount of carbon from sedimentary rock to the atmosphere?

A

Volcanic eruption

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21
Q

Define systems

A

Systems are groups of objects and the relationships that bind the objects together

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22
Q

What is a closed system?

A

A system with inputs and outputs of energy, but without any movement of materials across system boundaries

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23
Q

What is an open system?

A

A type of system whose boundaries are open to both inputs and outputs of energy and matter

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24
Q

What type of system are the water and carbon cycles at a global scale?

A

Closed systems

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25
Q

Why are the global water and carbon cycles closed?

A

Only energy (and not matter) can cross the boundaries of the global water and carbon cycles

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26
Q

What energy drives the global water and carbon cycles?

A

Sun’s energy (external to the Earth)

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27
Q

What type of system are smaller scale water and carbon cycles?

A

Open systems

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28
Q

Examples of smaller scale cycles (2 ideas)

A
  1. Drainage basins
  2. Forest ecosystem
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29
Q

Why can smaller scale cycles be considered open?

A

Materials as well as Sun’s energy can cross system boundaries

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30
Q

What % of global water is stored in oceans?

A

97%

31
Q

What % of global water is stored in polar ice and glaciers?

A

2%

32
Q

What % of global water is stored as groundwater (aquifers)?

A

0.7%

33
Q

What % of global water is stored in atmosphere?

A

0.001%

34
Q

How much water is frozen in the ice caps of Antarctica and Greenland?

A

3/4

35
Q

How much fresh water is stored below ground in permeable rocks?

A

Only 1/5 of all fresh water

36
Q

What can explain the fact that only a minute fraction of water is found in the atmosphere?

A

Rapid flux of water (into and out of atmosphere)

37
Q

What is the avg. residence time of a water molecule in the atmosphere?

A

9 days

38
Q

How much water does the global water cycle budget circulate per year (estimate) as inputs and outputs between the principal water stores?

A

505,000km3

39
Q

What are the main inputs and outputs of the water cycle? (7 ideas)

A
  1. Water vapour evaporated from oceans, soils, lakes and rivers
  2. Vapour transpired through the leaves of plants
  3. Precipitation (rain, snow, hail etc)
  4. Condensation (fog)
  5. Ice sheets, snowfields, glaciers release water by ablation (melting & sublimation)
  6. Run-off (drains precipitation & meltwater from land into rivers)- BUT some continental drylands drain to inland basins (i.e. S-W USA)
  7. After infiltrating soil, water may percolate (gravity) into permeable rocks/aquifers- eventually reaches surface (springs & seepages- contribute to run-off)
40
Q

What is the biggest stores of carbon AND how much (bn tonnes)?

A

Sedimentary (carbonate) rocks (i.e. limestone, chalk) and deep ocean sediments- 60,000 - 100,000,000

41
Q

Where is most of the carbon not stored in rocks & sediment found AND how much (bn tonnes)?

A

Oceans (as dissolved CO2)- 38,700

42
Q

What are the smallest stores of carbon AND how much (bn tonnes)? (3 ideas)

A
  1. Atmosphere (600)
  2. Land plants (560)
  3. Soils/peat (2,300)
43
Q

Why are these smaller stores of carbon still crucial?

A

Represent most of the carbon in circulation at any one time

44
Q

What are the 2 different strands of the carbon cycle?

A
  1. Fast cycle
  2. Slow cycle
45
Q

How long is carbon stored in rocks, sea-floor sediments and fossil fuels locked away for?

A

Millions of years

46
Q

What is the total amount of carbon in circulation by the slow cycle?

A

Between 10 - 100 million tonnes a year

47
Q

How does the slow carbon cycle work? (3 steps)

A
  1. CO2 diffuses from atmosphere to oceans- marine organisms (i.e. clams, corals) make their shells & skeletons by fixing dissolved carbon with calcium = calcium carbonate (CaCO3)
  2. Organisms die, sink to ocean floor
  3. Accumulate and over millions of years, heat and pressure convert them to carbon-rich sedimentary rocks
48
Q

What is the typical residence time for carbon held in rocks?

A

150 million years

49
Q

How is carbon held in rocks released? (2 ideas)

A
  1. Volcanic eruptions- carbon-rich sedimentary rocks = vented to atmosphere (subduction)
  2. Rocks exposed at surface (tectonic movements & erosion) = attacked by chemical weathering- i.e. carbonation attacks carbonate minerals in rocks, releasing CO2 to atmosphere, and in dissolved form to streams, rivers and oceans
50
Q

How do carbonaceous rocks form AND examples?

A

On land, partly decomposed organic material buried beneath younger sediments

e.g. coal, lignite, oil and natural gas (act as carbon sinks that endure for millions of years)

51
Q

Which stores does carbon circulate most rapidly between in the fast cycle? (4 ideas)

A
  1. Atmosphere
  2. Oceans
  3. Living organisms (biosphere)
  4. Soils
52
Q

How much quicker are the transfers in the fast cycle than in the slow cycle?

A

10 - 1,000 x faster

53
Q

What are the key components of the fast cycle? (2 ideas)

A
  1. Land plants
  2. Microscopic phytoplankton in the oceans
54
Q

How does carbon cycle in the fast cycle? (3 ideas)

A
  1. Photosynthesis- CO2 absorbed (land plants & phytoplankton- combine it with water to make carbohydrates e.g. sugars/glucose)
  2. Decomposition of dead organic matter by microbial activity- returns CO2 to atmosphere
  3. Atmospheric CO2 dissolves in ocean surface waters while the oceans ventilate CO2 back to atmosphere- through exchange, individual carbon atoms = stored (natural sequestration) in the oceans
55
Q

How long do individual carbon atoms remain in the oceans for?

A

Avg. 350 years

56
Q

What is dynamic equilibrium?

A

A system displaying unrepeated average states throughout time

57
Q

What happens in the short-term to inputs, outputs and stores of the water and carbon cycles?

A

They will fluctuate from year to year

58
Q

What happens in the long-term to flows and stores of the water and carbon cycle?

A

Usually maintain a balance, allowing a system to retain its stability

59
Q

What do negative feedback loops within systems do?

A

Restore balance

60
Q

Example of negative loop in a drainage basin (3 steps)

A
  1. Heavy rainfall increases water stores in aquifers
  2. Causes a raise to the water table, increasing flow from springs
  3. Water table reverts to normal level
61
Q

Example of negative feedback loop in the carbon cycle (3 steps)

A
  1. Burning fossil fuels increases atmospheric CO2
  2. At same time, stimulates photosynthesis (plant growth)
  3. Remove excess CO2 from atmosphere
62
Q

What is urbanisation?

A

The conversion of land use from rural to urban (i.e. farmland and woodland replaced by housing, offices, factories and roads)

63
Q

How does urbanisation affect the stores and flows in the water cycle? (4)

A
  1. Increased impermeable surfaces, allowing for little to no infiltration (store), increasing run-off (flow)
  2. Urban areas have drainage systems designed to remove surface water rapidly (i.e. pitched roofs, gutters, sewage systems), decreased lag time, increasing flood risk
  3. Removal of vegetation, decreased storage (interception & absorption), increased run-off (flow), decreased lag time so increased flood risk
  4. Encroaches on flood plains (natural store of water), reducing water storage capacity in drainage basins, increasing river flow and flood risk
64
Q

How does urbanisation affect the stores and flows in the carbon cycle? (2)

A
  1. Increased emission of CO2 (cars, factories etc) leading to increased atmospheric store
  2. Decreased vegetation, decreased photosynthesis, decreased storage of CO2 in biosphere
65
Q

How does farming affect the stores and flows in the water cycle? (3)

A
  1. Tractors and heavy machinery compact soil (impermeable), increasing run-off and river discharge
  2. Irrigation systems take water from rivers & groundwater- most is lost to evaporation, decreasing ground storage & river storage
  3. Ploughed furrows act as drainage channels, accelerating run-off and soil erosion
66
Q

How does farming affect the stores and flows in the carbon cycle? (3)

A
  1. Clearance of forest for farming reduces carbon storage in above and below ground biomass
  2. Ploughing releases carbon to atmosphere, creating a carbon source
  3. Soil erosion most apparent when crops have been lifted and soils have little protective cover, releasing CO2
67
Q

How does forestry affect the stores and flows in the water cycle? (4)

A
  1. Higher rates of interception- e.g. conifers’ needle-like structure, ever green and high density
  2. Increased evaporation- evaporated off leaf surfaces after interception
  3. Reduced run-off & discharge- high interception & evaporation and absorption of water by roots
  4. Transpiration rates increased- e.g. Sitka spruce in the Pennines around 350mm/year of rainfall equivalent
68
Q

How does forestry affect the stores and flows in the carbon cycle? (3)

A
  1. Increased store of carbon- e.g. mature forest trees contain on avg. 170-200 tones C/ha (10x higher than grassland, 20x higher than heathland)
  2. Increased carbon store in soil- in England, measurements of forest soil carbon around 500 tonnes C/ha
  3. Sequester carbon from atmosphere BUT only active carbon sink for first 100 years- forestry plantations rotation of 80-100 years to mitigate
69
Q

What is an aquifer?

A

A layer of permeable water-bearing rock that can contain or transmit water (e.g. chalk)

70
Q

What is abstraction?

A

The process of taking water out of the ground, temporarily or permanently

71
Q

What is the water table?

A

The level in the ground below which the ground is saturated

72
Q

What is groundwater?

A

Water that is held within the ground in the soil or in pores (spaces) in the rock

73
Q

What is recharge?

A

The replenishment of an aquifer by absorbing water from precipitation

74
Q
A

A Level Geography (OCR) (5 decks)

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