1 Water and Carbon Cycles Flashcards
What is the ‘Goldilocks zone’?
The Earth is the ‘right’ distance from the sun for water to exist in large quantities in liquid form
Use the comparison of Mars and Mercury to Earth to support the importance of liquid water to life
On Mercury, 48 million miles from the sun, surface temperatures of 430C mean that only water vapour can exist
On Mars 141 million miles, -65C, water exists at the pole in the form of ice - although there might be very small amount of liquid water too
How does water help to create benign thermal conditions on Earth?
Oceans (71% of Earth’s surface) moderate temperatures by absorbing heat, storing it and releasing it slowly
How do cloud moderate the environment?
Made up of tiny water droplets and ice crystal reflect around a fifth of incoming solar radiation and lower surface temperatures
How do ocean currents moderate the environment?
Redistribute heat from the equatorial regions towards the poles, preventing excessive heating and cooling of different parts of the planet
How does water vapour moderate the environment?
Greenhouse gas
Absorbs outgoing long-wave radiation, helping maintain a global average surface temperature of 15C (approx 35C warmer than it would be without)
Why is water important for flora (plants)?
Plants area nearly all autotrophic (manufacture their own food)
Photosynthesis - production of glucose from CO2 and water using solar radiation
Transpiration - of water from leaf surfaces cools plants
Respiration - converts glucose to energy by reacting with oxygen, releasing water and CO2 in the process
Require water for rigidity and a medium to transport minerals
Why is water important for fauna (animals)?
Makes up 65-95% of all living organisms
Crucial for growth, reproduction and other metabolic functions
Respiration converts glucose to energy by reacting with oxygen, releasing water and CO2
Medium for all chemical reactions and for vital processes such as blood and nutrient circulation
Why is water important for human uses?
Used in industry, to generate electricity, to irrigate crops, for recreation and leisure, for drinking water and sanitation
Why is carbon important to life on Earth?
Life is carbon based - amino acids (proteins), carbohydrates and nucleic acids
Economic resource - fossil fuels (coal, oil and natural gas)
Carbon-based crude oil is a raw material in manufacturing of products (plastics, paint, synthetic fabrics)
Biomass - agricultural crops and forest trees store large amounts of carbon available for human use as food, timber, paper, textiles and many other products
What is carbon?
Common chemical element
Stored in carbonate rocks such as limestone, sea floor sediments, ocean water (dissolve CO2), the atmosphere (CO2 gas) and in the biosphere
Describe the global water cycle
Closed system
3 main stores - atmosphere (smallest) , oceans (biggest) and land
Moves via precipitation, evapotranspiration, run-off and groundwater
Draw the global water cycle
Describe the global carbon cycle
Closed system
Long-term storage in sedimentary rocks (99.9% of all carbon)
Most of the carbon in circulation moves rapidly between atmosphere, ocean, soil and biosphere
Processes: photosynthesis, respiration, oxidation (decomposition, combustion) and weathering
Why can the water and carbon cycles be regarded as both open and closed?
Global:
Closed systems driven by the Sun’s energy (external)
Only energy cross boundaries
Smaller scales (drainage basin or forest ecosystem):
Open systems
Material also crosses boundaries
How is Earth’s water stored?
Oceans - 97%
Freshwater - 2.5% of water
Glacier and Ices caps - 2% total (68.7% of freshwater)
Aquifers - 0.7% total (30.1% of freshwater)
Lakes - 0.01
Soils - 0.005
Atmosphere - 0.001
Rivers - 0.0001
Biosphere - 0.00004
What are some inputs of water into the atmosphere?
Water vapour evaporated from the oceans, soils, lies and rivers, and vapour transpired through the leaves of plants - Evapotranspiration
How does water leave the atmosphere?
Precipitation and condensation
Ice sheets, glaciers and snowfields release water by ablation (melting and sublimation)
Where does precipitation and meltwater drain to?
Drains from the land surface as run-off into rivers
Most rivers flow to oceans, some to inland basins
Majority of water as precipitation reaches rivers only after infiltrating and flowing through the soil
Where does the water go after infiltration?
Water under gravity may percolate into permeable rocks or aquifers
This groundwater eventually reaches the surface as springs/seepages and contributes to run-off
What are the main stores of the global carbon cycle?
Atmosphere, oceans, carbonate rocks, fossil fuels, plants and soils
How much carbon is in each of the stores?
Carbonate rocks, limestone and chalk, and deep-ocean sediments are by far the biggest carbon store (60000-100,000,000 billion tonnes)
Oceans as dissolved CO2 (38,700)
Atmosphere (600)
Land plants (560)
Soils/peat (2300)