Physical - Carbon and Water Cycles Flashcards
The cycles as natural systems:
Concept of a system:
A system is the ‘big picture’ of inputs, outputs, transfers and stores, and its links to other systems. They have boundaries and structures and their components interlink and work together.
The cycles as natural systems:
Concept of a system:
Open Systems:
These are systems where both matter and energy can be transferred from, across the boundary into the surrounding environment.
The cycles as natural systems:
Concept of a system:
Closed systems:
A system where energy can be transferred, but not matter across boundaries.
The cycles as natural systems:
Concept of a system:
The components of a system:
Elements: parts that make up the system (animals, atoms, etc)
Attributes: characteristics that can be measured (size, colour, quantity, etc)
Relationships: descriptions of how the elements and their attributes work together to carry out processes (photosynthesis).
The cycles as natural systems:
Concept of a system:
Systems are affected by feedbacks:
1. If the inputs and outputs are balanced, the system is in equilibrium (flows and processes can continue, but consistently so there are no overall changes
2. But, in reality many very small variations in the inputs and outputs happen, and so they stay about equal on average. This is the system in dynamic equilibrium.
3. Larger longer term changes to the balance can cause a system to change and establish a new dynamic equilibrium (an overall shift).
4. These changes can cause positive/negative feedback loops
Positive: these amplify the changes (like the albedo loop)
Negative: these counteract the change and decrease its effects (plants decreasing CO2 in the atmosphere).
The cycles as natural systems
Water cycle systems:
Water cycle systems:
The water cycle on a global scale is a closed system (as no water can come from space).
But on a local scale, it is an open system (a pond with water coming from precipitation, stores of plants, transfers of photosynthesis and groundwater flow, and outputs of evaporation).
The cycles as natural systems:
Carbon cycle systems:
Carbon cycle systems:
On a global scale, the carbon cycle is closed (as no carbon matter comes from space).
But, on a local scale, it is open (e.g. a forest system, with inputs of lead fall, stores of rocks or trees, flows of photosynthesis, respiration and outputs of atmospheric emissions from forest fires).
The cycles as natural systems:
Why is the cycling of water important:
Water:
- It ensures that availability and quantity of water which is fundamental to life of Earth.
- It facilitates key interactions between the land, ocean and atmosphere.
- It creates water vapour, which is the most abundant greenhouse gas, and regulates global temperatures.
- It allows scientists to predict the planet’s future and climate.
The cycles as natural systems:
Why is the cycling of carbon important:
Carbon:
- It ensures that carbon is transferred to where it needs to be. Carbon is what all life is made of and must be distributed by this cycling.
- Carbon can form greenhouse gases that regulate the Earth’s temps.
- The cycle facilitates vital interactions and distribution processes between the land, oceans and atmosphere.
The cycles as natural systems:
The Earth as a system:
The Earth can be seen as a closed system (energy input from the sun and output to space, but no matter is transferred to space).
It has subsystems:
- Cryosphere: all ice in the world (glacial landscapes, Antractica)
- Lithosphere: the Earth’s crust and upper mantle (rocks and soils)
- Biosphere: all living things on Earth (plants, animals)
- Hydrosphere: all water on earth (liquid, solid, gas, saline, fresh) (this crosses over with the cryosphere).
- Atmosphere: the gases between the Earth’s surface and space.
These are interlinked by the water and carbon cycles, matter and energy is transferred across to each system from another (this is a cascading system).
The Carbon Cycle:
Global distribution and major global carbon stores:
Carbon is in both organic (living) and inorganic (non-living, rocks, gases, fossil fuels) stores.
Main global sotres:
1. Lithosphere: Over 99.9% of carbon is stored in sedimentary rocks, and 0.004% is stored in fossil fuels.
2. Hydrosphere: The oceans are the next biggest store (0.04%) with most being from deep oceans in the form of dissolved inorganic carbon (CO2 and other gases are dissolved in water). Some carbon is at the surface and is transferred into the atmosphere.
3. Atmosphere: Carbon is stored as CO2 or methane here (0.001% overall).
4. Biosphere: Carbon is stored in the tissues of living organisms (transferred to the lithosphere when they die and decay) (contains 0.004% overall).
5. Cryosphere: contains less than 0.01% of carbon. Most is in permafrost, where decomposing organic matter is frozen into the ground.
The Carbon Cycle:
Carbon is transferred between stores:
The carbon cycle is a process where carbon is stored and transferred.
It is a closed system, but some carbon is locked away (sequestered) in long term stores (rocks, fossil fuels) and they effectively become inputs when they are released.
The Carbon Cycle:
Main stores and flows of the cycle:
Stores:
- Soils, Earth’s crust (rocks), fossil fuels, vegetation, sediments, oceans, atmosphere.
Flows:
1. Inputs: photosynthesis, decomposition, sequestration, weathering, ocean uptake.
2. Outputs: volcanic eruptions, burning fossil fuels, combustion, respiration, ocean loss.
The Carbon Cycle:
Carbon stores change in size over time due to carbon flows:
Carbon flows between stores that force the change:
1. Photosynthesis:
This transfers between the atmosphere and biomass.
Plants use energy from the sun to change CO2 and water into glucose and oxygen, enabling growth.
Carbon is passed through the food chain and released through respiration and decomposition (longer term).
The Carbon Cycle:
Carbon stores change in size over time due to carbon flows:
- Respiration:
This transfers carbon from living organisms to the atmosphere.
Plants and animals break down glucose for energy, releasing CO2 and methane into the atmosphere.
The Carbon Cycle:
Carbon stores change in size over time due to carbon flows:
- Decomposition:
This is the transfer of carbon from dead biomass to the atmosphere and soils.
After death, bacteria and fungi break down the organic matter and release CO2 and methane.
Some carbon is transferred into the soil in the form of humus (dark organic material).
The Carbon Cycle:
Carbon stores change in size over time due to carbon flows:
- Combustion:
This is the transfer of carbon in living, dead or decomposed biomass into the atmosphere, by burning.
Wildfires are natural forms of this.
The Carbon Cycle:
Carbon stores change in size over time due to carbon flows:
- Weathering
Chemical weathering transfers carbon from the atmosphere to the hydrosphere and biosphere
Atmospheric carbon reacts with the water vapour to form acid rain. When this falls onto rocks, a chemical reaction occurs, dissolving the calcium in the rocks. This is washed into the sea and reacts with the CO2 in the water, forming Calcium Carbonate that forms the shells of sea creatures.