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Earth's life support systems - OCR Paper 1
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Detailed notes on earth's life support systems for paper 1 OCR a level geography. All the content which you need for your exams.
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Earth’s Life SupportSystems
, Importance of Carbon and Water Cycle
GOLDILOCKS ZONE: earth is the perfect distance away from the sun, to allow water in a liquid form
LITHOSPHERE: outer rigid part of the earth, including the crust and upper mantle and is divided into tectonic plates
BIOSPHERE: occupied by living organisms
HYDROSPHERE: all the water on the earth
CRYOSPHERE: the frozen part of the earth
ATMOSPHERE: all the gases surrounding the earth
CARBON WATER
- 0.04% of air - Drinkable
- Stored in carbonate rocks such as limestone, sea floor - People
sediment, ocean water, the atmosphere and in the Manufacturing e.g. brewing/ paper making/food
biosphere Economic activity e.g. irrigation, electrics
- Economic resource Oxygen circulation and nutrients
For fossil fuels (oil, natural gas and coal) - Fauna
Oil is also used as a raw material in production, from Panting - cooling
plastics to paint and synthetic fabrics Used for chemical reactions
- Agriculture crops and forest trees store carbon - Flora
Used by humans e.g. food, timber, paper, textiles etc. Photosynthesis
Respiration
Maintaining rigidity to transport minerals
Transpiration cools down the plant
- Climate
Water vapour absorbs longwave radiation
Clouds reflect ⅕ of solar radiation to lower temp
Creates stable thermal conditions
Oceans (71%) absorb heat
, Water Cycle
DRAINAGE BASIN: area of land which is drained by a river
FACTORS AFFECTING INTERCEPTION LOSS
LAG TIME: how long it takes for rain to flow in streams Wind speed
PRECIPITATION - Rates of evaporation increase with wind speed
Vegetation type
1. Water vapour in the atmosphere cools - Trees = large surface area = increases interception
to dew point loss
2. Condenses into tiny droplets/ice - Greater from grass than crops
particles to form clouds Tree species
3. Reach a certain size and leave the cloud - Increases in evergreen conifers compared to
Variation in rain intensity changes impact e.g. heavy rain deciduous trees as they have leaves yearly and water
bounces on ground = compresses = overland flow adheres to space between conifer needles = increases
Variation in duration too much rain = water log evaporation
Seasonality of rainfall river discharge and flooding (winter), Interception storage capacity
summer = increased evapotranspiration - Initially rainfall is intercepted (dry vegetation) and is
Interception - vegetation intercepts TRANSPIRATION then saturated as output through stemflow increases
precipitation as temporary storage and
Diffusion of water vapour to the atmosphere CLOUDS
eventually evaporates or falls on ground
from the stomata of plants Cumuliform - flat based, vertical development
Infiltration - by gravity into the soil
10% of the moisture Air heated from earth surface = rise freely
Throughflow - to streams and rivers
Influenced by temp, wind speed, water (convection) = expand (pressure falls) = cools to
Overland flow - across ground surface as
availability dew point = condensation
sheet or trickles and when rainfall exceeds
infiltration rate Stratiform - layered
Saturated/ really dry soil = overland flow More trees = more interception When air mass moves horizontally across cool
Percolation - water flowing through pore Winter = less transpiration and less surface (advection)
spaces in permeable rock interception Cirrus clouds - form at high altitude, tiny ice
Advection - horizontal movement of water Snow = less infiltration and groundwater crystals
through atmosphere storage Don’t produce precipitation
Antecedent conditions - soil before due to More streams = more channel precipitation
previous conditions Drip flow = from the leaves
Groundflow - through geology Stem flow = through the stem
, Carbon Cycle PHOTOSYNTHESIS
Land plants and phytoplankton - 120 gigatones annually
Largest store = lithosphere Others = oceans, hydrosphere, cryosphere, Energy used as glucose for growth and reproduction
biomass Carbon sink
Most carbon = above tropic of cancer Least = Arctic and Antarctic
Sedimentary rock holds 99.9% RESPIRATION
PRECIPITATION Part of fast carbon cycle
Anthropogenic emissions = increase rainfall acidity = increases Rate of decomposition depends on climate
C02 in atmosphere = increases acidity of ocean surfaces = Plants and animals absorb oxygen and burns carbohydrates and
harmful to marine organisms provides energy for metabolism and growth
C02 dissolves in rainwater = forming weak carbonic acid
WEATHERING
COMBUSTION In situ breakdown of rock
Fossil fuels Rainwater contains dissolved C02 = weak carbonic acid = slowly
Organic matter burns with oxygen dissolves limestone and chalk
Releases C02, sulphur dioxide and nitrogen oxides Carbonation releases carbon from limestone to streams, rivers,
Wildfires caused by lightning oceans and atmosphere
Burning for cultivation and grazing Biological weathering - chelation - water mixed with dead and
decaying organic material in the soil = forms humid acids =
SLOW CARBON CYCLE attacks minerals
1. CO2 is trapped in rocks and dissolved C02, 02, Ca is used Physical weathering - freeze thaw = increases SA and breaks
by marine organisms to create calcium carbonate to form down rock
shells and skeletons Chemical weathering - transfers 0.3 billion tonnes of carbon
2. Organisms die and sink to sea floor yearly
3. After millions of years, the pressure and heat changes
shells into carbon rich sedimentary rock (limestone) FAST CARBON CYCLE
4. Tectonic processes subduct limestone into mantel - 1. Phytoplankton captures the sun’s energy to
dehydrates and is released into atmosphere as C02 photosynthesise
5. C02 is released from rocks due to chemical weathering. 2. Carbohydrates feed aquatic life in the food chain
Weak acids in rainwater dissolve carbonate chemicals, 3. They either die and decompose = C02 returned to atmos
releasing C02 into the atmosphere, rivers and oceans or they respire = C02 returned to atmos
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