Topic 1: Water and Carbon Cycles (P) ✿ Flashcards
What are inputs?
Inputs are when matter or energy is added to a system
What are outputs?
Outputs are when matter or energy leaves the system
What are stores?
Stores are where matter or energy builds up
What are flows/transfers?
Flows/Transfers are when matter or energy moves between stores
What are boundaries?
Boundaries are the limits of a system
What are open systems?
Open systems are when both energy and matter can enter and leave the systems eg drainage basins
What are closed systems?
Closed systems are when matter can’t enter or leave a system (but energy can) eg carbon cycle
What is meant by dynamic equilibrium?
Dynamic equilibrium is when there is a state of balance between inputs and outputs. If changes do occur then feedback will allow for correction.
What is a positive feedback?
Positive feedback is when mechanisms amplify the change in inputs or outputs - meaning the system increases the effects of the change
What is negative feedback?
Negative feedback are mechanisms counteracting the change in the inputs or outputs, trying to decrease the effects to keep it at its normal state.
What is the cryosphere?
The cyrosphere consists of all the frozen water components of earth eg glaciers
What is the lithosphere?
The lithosphere is the outermost part of the earth which includes the crust and the upper parts of the mantle
What is the biosphere?
The biosphere is where all living things are founds
What is the hydrosphere?
The hydrosphere includes all of the water on earth
What is the atmosphere?
The atmosphere is the layer of gas between the earth’s surface and space
Where is fresh water found on earth?
Fresh water on earth:
69% frozen in cyrosphere
30% is groundwater
0.3% is liquid freshwater
0.04% is water vapour in the atmosphere
What does magnitude of water in stores depend on?
Magnitude depends on seasonal factors and location
Why does condensation occur?
Condensation occurs when energy is lost and it cools down, resulting in water vapour cooling to its due point
What are the three causes for warm air cooling down, leading to precipitation?
Other air masses - warm air is less dense than cool air so it’s forced up and cools as it rises - results in frontal precipitation
Topography - warm air rises when it reaches mountains and cools - orographic precipitation
Convection - sun heats the ground and evaporation occurs, and water vapour cools as it rises - convective precipitation
How does cryospheric processes impact water storage?I
Accumulation and ablation change the amount of water stored as ice in the cryosphere, which depends on temperature
Cool temperatures: inputs greater than outputs
Warm termperatures: magnitude decreases due to melting
What is interception?
Interception is when vegitation temporarily store water from precipitation, but only for a short time due to evaporation and throughfall
What is the water table?
The water table is the top surface of the zone of saturation
What are aquifiers?
Aquifiers are porous rocks that hold water
What is throughfall?
Throughfall is water dripping from one leaf to another
What is throughflow?
Throughflow is water moving slowly downhill through the soil
What is percolation?
Percolation is water seeping down through soil into the water table
What is groundwater flow?
Groundwater flow is water moving slowly below the water table through permable rock. Rocks that are highly permeable with lots of joints has faster groundwater flow eg limestone
What is baseflow?
Baseflow is groundwater flow that feeds into rivers through river banks and river beds
What is interflow?
Interflow is water flowing downhill through permable rock above the water table
What creates a water surplus?
Water surplus is created when precipitation exceeds evapotranspiration. The ground stores fill with water so there’s more surface runoff and higher discharge so river levels rise
What happens in drier seasons?
In drier seasons, precipitation is lower than evapotranspiration. Ground stores are depleted as some water is used and some flows into the river channel, but isn’t replaced by precipitation
Why is autumn important?
In autumn, the groundwater stores are recharged due the dry season where there was a shortage of water in the ground
What are the local factors that affect water storage?
Local factors affecting water storage:
-Deforestation
-Storms
-Seasonal changes
-Urbanisation
-Farming
How does deforestation impact water storage?
Deforestation reduces interception and infriltation, but overland flow increases.
River channel increases
How does storms impact water stores?
Storms increase overland flow and through flow, but decrease infriltation. They increase all stores, ie river channels
How does urbanisation impact water stores?
Urbanisation reduces infriltation and increases overland flow
Decreases interception and increases river channel
How does farming impact water stores?
Farming decreases river channel and surface storage due to water extraction for farming
How does seasonal changes impact water stores?
Season changes decrease infriltration, percolation and through flow, resulting in stores decreasing such as the river channel, groundwater and soil water
What is sublimation?
Sublimation: solid directly to gas
What is ablation?
Ablation is melting ice/solids
What is leaching?
Leaching is rainfall washing through soil and carrying the nutrients out of a system
What is decomposition?
Decomposition is organic matter decaying to release nutrients
What is evapotranspiration?
Evapotranspiration is the combined return of water to the atmosphere from evaporation and
transpiration
What is streamflow?
Streamflow is water that flows through streams and into the ocean or as tributaries to other
rivers
What is stemflow?
Stemflow is the flow of water that has been intercepted by plants or trees, down a stem, leaf,
branch or other part of a plant
How do you calculate water balance?
Precipitation = total runoff + evapotranspiration +/- storage
How does deforestation impact the water cycle on a local scale?
Deforestation - less interception, soil less likely to absorb water
How does storm events affect the water cycle on a local scale?
Storm events increase surface runoff and water storage
How does seasonal changes affect the water cycle on a local scale?
Seasonal changes - More
interception in spring; Snow reduces
flows; Hot weather reduces
precipitation
How does agriculture affect the water cycle on a local scale?
Agriculture - Pastoral (Livestock)
ground trampled so less infiltration;
Arable (Crops) - Ploughing increases
infiltration. Ditches increase runoff
What is the soil water budget?
Soil water budget is the change in soil water store during the year
What happens to the soil water budget throughout the year?
There is a surplus of water in the winter months, after recharge of soil water in autumn. Soil water
is recharged in autumn because the inputs of precipitation exceed the outputs of
evapotranspiration (because it rains more and it is cooler).
The water is utilised in spring and summer, when potential evapotranspiration of plants is highest
due to warmer weather.
The stores are depleting when evapotranspiration is greater than precipitation . This can lead
to a deficit of soil water.
What is meant by field capacity?
Field capacity is when the soil holds as much water as it can without any outputs occuring
What are the characteristics of systems?
Characteristics of systems:
-Generalisations of reality
-Have a structure that’s defined by its parts and processes
-Function in the same way - inputs and outputs
-Connected together
-Functional relationships exist between parts
-Exchange energy +/or matter beyond its defined boundary
Transfers involved in the carbon cycle
Transfers involved in the carbon cycle:
-Photosynthesis
-Combustion
-Respiration
-Decomposition
-Diffusion
-Weathering and erosion
-Sequestration
What is sequestration in the carbon cycle?
Sequestration is carbon being stored away eg in rocks
What are the carbon stores in the carbon cycle?
Carbon stores:
-Marine sediments and sedimentary rock
-Oceans
-Fossil fuel deposits
-Soil organic matter
-Atmosphere
-Terrestrial plants
Natural processes that impact the carbon cycle
Natural processes that impact the carbon cycle:
-Wildfires
-Volcanic activity
Human processes that impact the carbon cycle
Human processes that impact the carbon cycle:
-Fossil fuel usage
-Deforestation
-Farming practises
Carbon forms
Carbon forms:
-Carbon dioxide (gas in atmosphere, soils, oceans)
-Methane (gas in atmosphere, soils, oceans, sedimentary rock)
-Calcium carbonate (solid compound in rocks, oceans, marine organism skeletons)
-Hydrocarbons (solids, liquid or gas in sedimentary rocks)
-Bio-molecules (complex carbon compounds in living things eg carbs)
Negative feedback
In negative feedback, the process that occurs is counteracted by an opposing process, causing the effects to cancel each other out and nothing to change
Positive feedback
In positive feedback, a process occurs which causes another process to occur, which starts a chain reaction that heightens the first process
Positive feedback in hot climates
Positive feedback in hot climates:
-Wildfires created by global warming releases large amounts of CO2 into the atmosphere which increases the warming effect
-High temperatures thaw permafrost and release CO2 and methane, leading to further warming
-As sea temp rises and ice melts, warming effect increases as there’s less ice to reflect the sun’s heat
Negative feedback and climate change
-Increased photosynthesis from rising temp > more vegetation growth > more co2 absorbed > warming effect decreased
-High temp and CO2 levels increase carbon fertilisation in plants > absorb more co2 from atmosphere
-High CO2 levels cause phytoplankton to grow > more photosynthesis > less CO2 in atmosphere
-More phytoplankton > releases substances that cause cloud formation > less radiation from sun reaching oceans > reduces temp > phytoplankton decreases
Amazon rainforest characteristics
Amazon rainforest characteristics:
-Largest rainforest in the world
-300 billion trees + 15000 species
-Stores 1/5 of all carbon in plant’s biomass
-Found in South America - spreads across 9 countries
-Home to 34 million people
-Closed system (most water does not leave the system, only 30% of water enters sea wheras rest is evapotranspired, intercepted, etc
Carbon storage in the amazon rainforest
Carbon storage in the amazon rainforest:
-UFZ estimated that Amazon rainforest was a carbon sink in 2019, absorbing around 600 million tonners per year
-The increase in atmospheric CO2 -> growth spurt of Amazon’s basin trees -> growth stimulation feeds through system, causing trees to live faster and die younger
-Increased surge in rate of tree deaths in the amazon rainforest
Water storage in the amazon rainforest
Water storage in the amazon rainforest:
-Average discharge of water into the Atlantic Ocean by the Amazon approx 175,000 m^3/s entering each day
-Rio Negro (tributary of the Amazon) second largest river - 100m deep and 14km wide
-Average rainfall across whole Amazon basin approx 2300 mm annually - some may never reach grown due to interception of forest canopy
Drivers of change of the Amazon Rainforest
Drivers of change of the Amazon Rainforest:
-Deforestation (rate of almost 20,000km per yr between 2000-2007)
-Brazil is world’s 4th largest climate polluter (75% attributed to deforestation and land use change)
-Slash and burn techniques to remove forest
-Moisture evaporated from deforestated areas forms shallow cumulous clouds which usually do not produce rain
-If destroyed, vast carbon store released into the atmosphere
Effect ofslash and burn techniques to remove forest (eg in the Amazon Rainforest)
Effect of slash and burn techniques to remove forest (eg in the Amazon Rainforest):
-Reduces the retention of humidity in the soil’s top layer down to a depth of one emtre
-Facilitates sudden evaporation of water previously retained in the forest canopy
-Increases albedo (reflectiveness) and temperature
-Reduces porosity of soil, causing faster rainfall drainage and erosion
Changes of climate in the Amazon rainforest
Changes of climate in the Amazon rainforest:
-Temperature increase of 0.25-0.5 degrees celcius every ten years since mid 1970s
-Temperature expected to increase by 2-3 degrees celcius by 2050
Vegetation changes in the amazon rainforest
Vegetation changes in the amazon rainforest:
-WWF estimates that 20% of rainforest already been lost, due to deforestation and climate change
Soil changes in the Amazon
Soil changes in the Amazon:
-Amazon soils contain 4-9kg of carbon in upper 50cm of soil layer, 30-60% of this is released when the forest is burnt
-When forest clearance first occurs, soils are exposed to heavy tropical rainfall -> rapidly washes away topsoil and attacks deep weathered layer below > moist soil washed away into rivers
River changes in the Amazon Rainforest
River changes in the Amazon Rainforest:
Changes in total precipitation, extreme rainfall events and seasonality may:
-Overall reduction in river discharge
-Increase in silt washed into rivers which could disrupt river transport routes
-Destroys freshwater ecosystems
-Destroy water supply for amazonian peoples
Warming water temp may kill off temp-dependant species and change river system biodiversity
Process of combustion in the carbon cycle
Process of combustion in the carbon cycle:
-It is a flow/transfer of carbon
-Carbon is transferred from solid to liquid/gaseous state
-Can come from wildfires and volcanic activity
-Carbon gets transferred from biosphere or lithosphere store to the atmosphere store
Impact of changing land use on the shape of a flood hydrograph
Impact of changing land use on the shape of a flood hydrograph:
-Flashy hydrographs (high peak discharge and short lag time)
-Land use-> impermeable surfaces -> high run off
-Urbanisation -> removes vegetation -> less interception
-Increased flooding increases peak discharge and shortens lag time
-Drainage basin acts as open system, meaning they are affected by inputs and outputs
-Changes in the water cycle over time could also include storm events, seasonal changes and human activity
Whst are the major stores of carbon?
Major stores of carbon = lithosphere, hydrosphere, cryosphere, biosphere, atmosphere
Natural carbon sequestration
Natural carbon sequestration -> processes such as organic matter falling to the ocean floor where it accumulates as carbon-rich layers of sediment where they eventually lithify (become stone) -> increases the lithosphere store
Human process of carbon sequestration
Human process of carbon sequestration -> planting vegetation to remove CO2 from the atmosphere and storing it as organic material in the biosphere store and decreasing the atmosphere store
Impacts of deforestation on the flow of water in a tropical rainforest
Impacts of deforestation on the flow of water in a tropical rainforest:
-Reduced evapotranspiration from plants -> less condensation and precipitation
-Air warms more quickly over land in cleared areas of forest, crating localised low pressure and thunderstorms -> increases precipitation rates at a local scale
-Exposed soils -> increases rates of infiltration, percolation and soil water and ground flows
Effect of land use change in the flow of water through a tropical rainforest
Effect of land use change in the flow of water through a tropical rainforest:
-Land use changes -> building settlements -> overland flow, infiltration and river discharge within affected drainage basin hydrological system
Effect of water abstraction on the flow of water through a tropical rainforest
Effect of water abstraction on the flow of water through a tropical rainforest:
-Water abstraction -> for agriculture -> lowers the water table -> reduces channel flow (discharge) in local rivers
