W & C cycles: Importance of Water and Carbon Flashcards
Explain the importance of water in supporting life on the planet (for humans, flora and fauna). (1.a)
- Humans: Water makes up 60-75% of human body
weight. Humans cannot survive for more than 3 days without water. Water is the medium used for all chemical reactions
in the body including circulation of oxygen and nutrients. - Flora: Water needed for photosynthesis, which
generates glucose & starches. Water also used in transpiration to cool plants. - Fauna: Water acts as a solvent for nutrients and oxygen in animals, generating glucose and starches.
Explain how carbon is the building block of life Earth (for natural world, for humans). (1.a)
- Natural World: Carbon forms 95% of all known compounds on Earth. It also provides a natural greenhouse effect, allowing for life to exist.
- Humans: Humans cannot live without carbon and they are made up of 18% of this element. Carbon makes up the finite resource of fossil fuels essential in society.
Distinguish between open and closed systems. Isolated systems? (1.a)
- Open systems allow for energy and mass to pass the system boundary. Example: The Ocean. Energy and heat (via solar radiation) as well as mass (through water vapour and precipitation) pass through. (Explain evaporation basically).
- Closed systems allow energy, but not mass to pass the system boundary. Example: The Earth as a whole. Mass is generally not exchanged BUT energy as solar radiation between the sun and Earth does pass the atmosphere into the Earth system.
- Isolated systems do not allow mass or energy to pass the system boundary.
Analyse how water is cycled (i.e. slow and fast flows) between land, oceans and atmosphere through open and closed systems? (1.a)
=> In an open system, water moves much more freely. It is evaporated from rivers, lakes and oceans, forming clouds in the atmosphere as water vapour cools and condenses. Via precipitation, water on surface stores are replenished. Eventually, water flows back through rivers and streams into oceans.
=> In a closed system, after water is added initially via precipitation from the atmosphere, it is absorbed by plants or utilised for other purposes including by humans. Through flows such as transpiration or evaporation, water vapour exists the system, but is collected and condensed back into liquid form for reuse, ensuring that a closed loop of water recycling is created.
Analyse how carbon is cycled (i.e. slow and fast flows) between land, oceans and atmosphere through open and closed systems? (1.a)
=> In an open system, carbon is exchanged between the different spheres such as the atmosphere and the biosphere. CO2 is exchanged via the atmosphere and biosphere via processes like photosynthesis and respiration. Plants take CO2, converting it into organic carbon, which is then consumed by animals. When animals respire, they release CO2 back into the atmosphere.
Fast: Between the land and ocean, carbon is exchanged through ways such as photosynthesis and respiration of organisms like phytoplankton. Alternatively, gas exchange via CO2 from the atmosphere dissolves into the surface layer of the ocean, it diffuses into an area of lower concentration of CO2.
NOTE: Slow store. Carbon rich sedimentary rock. Can be subducted and release by volcanic activity.
=> In a closed system, after carbon is initially introduced into the system via organic matter, such as plant material. During decomposition, organic matter can be broken down into CO2. CO2 can be converted by plants into organic carbon, which can be consumed in other forms by animals. When animals respire, they release CO2, which again can be utilised by plants, closing the loop of carbon cycling.
Describe water cycles as systems with inputs, outputs and stores.
=> Inputs:
Precipitation: (water in any form, such as rain, hail, sleet). Water vapour condenses in the atmosphere and falls into the system.
Surface runoff: Water enters stores through this input. It does not infiltrate, but runs over the land. Eventually enters rivers, lakes and oceans.
Infiltration/ Percolation : Some precipitation infiltrates into the soil moisture store. May move through porous soil and percolate further, replenishing the groundwater store and aquifers.
=> Outputs:
Evaporation: Water is lost from the Earth’s surface as high temperatures and solar radiation converts liquid water into water vapour, which enters the atmosphere.
Transpiration: Plants absorb water through their roots and release it to the atmosphere through their stomata.
=> Stores:
Atmosphere: Contains 0.001% of water, which tends to be cycled to different stores quickly. Stores evaporated water vapour as humidity.
Oceans: 97% of water, largest store. Source of evaporation. Destination for precipitation and runoff.
Surface Water: Such as lakes and rivers. Receive input from precipitation, runoff, and groundwater discharge. Releases via evaporation evaporation and river discharge.
Describe the carbon cycle as a system with inputs, outputs and stores.
=> Inputs:
Atmospheric CO2: CO2 is constantly being exchanged between the atmosphere and terrestrial ecosystem by processes such as respiration, combustion and volcanic activity.
Photosynthesis: Includes organisms such as plants, algae and phytoplankton. Converts atmospheric CO2 into organic carbon compounds, incorporating carbon into the biosphere.
=> Outputs:
Respiration: Organisms release CO2 in return for energy, returning carbon as CO2 back into the atmosphere.
Decomposition: Can be caused by bacteria and fungi. They release CO2 back into the atmosphere after breaking down dead organic matter.
Combustion: Burning of fossil fuels release CO2 back into the atmosphere.
=> Stores:
Biosphere: Involves plants, animals and microorganisms, who act as stores of living biomass.
Oceans: A massive reservoir for dissolved CO2, also involved in marine shell and skeleton.
Fossil fuels: Formed over millions of years, these hold carbon accumulated until burnt via human activity.
Examine the distribution and size of major stores in water systems: atmosphere, ocean, water bodies, ice (cryosphere), soil, vegetation and groundwater.
=> 97% of water is stored in oceans. This is saline. The other 3% is fresh water.
=> 2% is stored in polar and glaciers. (67% of fresh water).
=> 0.7% is stored as groundwater/ aquifers.
=> Lakes hold 0.01%
=> Soil moisture/ Atmosphere: 0.001%
Examine the distribution and size of major stores in carbon systems.
=> Sedimentary rocks and ocean sediment: 100,000 bn tonnes.
=> Oceans: 39,000 bn tonnes.
=> Fossil fuels: 4,000 bn tonnes.
=> Soil: 1,500 bn tonnes.
=> Atmosphere: 720 bn tonnes.
=> Plants: 560 bn tonnes.
Water cycle: Spatial change for precipitation, snowmelt (ablation) and evapotranspiration.
Spatially:
=> Precipitation: Warmer climate increases this, allowing for greater water holding capacity. Increases in tropics and high latitudes. Decreases in 10-30 degrees North and South of the equator around desert areas (experience less than 250mm of water annually.
=> Evapotranspiration: Can vary based on vegetation density. Areas such as rainforests will have higher evapotranspiration, as there are more plants to release water, thus also influencing evaporation. -> More moisture in the atmosphere for precipitation, more water can return to the ground, be cycled back by evaporation. Rainforest V Desert again.
=> Snowmelt (Ablation): Higher altitudes experience colder temperatures, so see slower snowmelt. Lower altitudes see faster melting. Aspects facing the sun may melt faster too.
Water cycle: Temporal change for precipitation, snowmelt and evapotranspiration?
=> Precipitation: Seasonal variation. Greater precipitation during winter months and rainy seasons V lower precipitation during summer months and dry seasons.
=> Snowmelt (ablation): Certain times of the years may experience warmer temperatures and greater solar radiation/ isolation leading to faster snowmelt. (Summer!)
=> Evapotranspiration: Much higher in summer months due to warmer temperatures increasing rates. Also longer days (so stomata of plants stay longer open).
Carbon cycle: Spatial change for precipitation (carbonic acid in rain), photosynthesis, decomposition, weathering (main forms of chemical weathering), respiration, combustion.
=> Carbonic acid in rain: High levels of precipitation and carbon rich rock regions.
=> Decomposition: Places such as rainforests with high temperatures, high levels of rainfall and much organic matter will have much faster rates of decomposition. In comparison, places like the Arctic Tundra will not.
=> Photosynthesis: Spaces with sufficient sunlight water and nutrients.
=> Chemical weathering: Areas with high rainfall and temperatures, especially in tropical regions, experience accelerated chemical weathering processes.
=> Respiration: Depends on temperatures primarily, higher temperatures can help to accelerate biochemical reactions.
=> Combustion: Either highly industrialised nations OR nations which make use of high levels of slash and burn deforestation. E.g China for the former, Brazil for the latter.
Carbon Cycle: Temporal changes for precipitation (carbonic acid in rain), photosynthesis, decomposition, weathering (main forms of chemical weathering), respiration, combustion.
=> Carbonic acid in rain: May vary on season depending on atmospheric carbon dioxide levels. E.g more in Spring and summer due to vegation growth.
=> Photosynthesis: Varies seasonally. May vary diurnally too.
=> Decomposition: Higher in warmer months as influenced by temperatures. -> Microbial activity is more active and organic matter turnover is accelerated.
=> Chemical Weathering: Higher in wetter and warmer climates like the Amazon, leading to increased carbon release from minerals and rocks over time.
=> Respiration: Increases generally with warmer periods and decreases during colder months.
=> Combustion: Seasons may vary practices, such as August being a prime time for slash and burn.
