carbon EQ1 Flashcards
What is carbon
An chemical element with a simple atomic structure that has the ability to bond with other elements
Relates complex molecules which are the basis of living matter
Why does plant life rely on carbon
It is necessary for photosynthesis
What are the 4 main carbon stores, and what form does carbon take in each
The atmosphere - as CO2 and CH4
The hydrosphere - dissolved as CO2
The lithosphere - as carbonates in limestone and fossil fuels such as coal oil and gas within rock
Biosphere - in living and dead organisms
What is the largest flux of carbon
Photosynthesis
What is the smallest flux of carbon
Volcanic eruption
What is a dynamic equilibrium of carbon
A situation in which the total amount of carbon entering a system is balanced by the total amount of carbon leaving
What causes variation in the dynamic equilibrium of the carbon cycle
Natural variation through forest fires and climate
Main variation is fossil fuel combustion and land cover Change
What are deep ocean hydrothermal vents
Fissures in the planets surface which issue geothermally heated water and minerals
Commonly fund close to tectonic margins especially divergence at mid ocean ridges or hotspots
How often does the entire ocean circulate though hydrothermal vents
Every 40 million years
What is known as the slow carbon cycle
Geological cycle
What is the geologic carbon cycle
The cycling of carbon through rock in the lithosphere taking millions of years
What is the geological carbon cycle driven by?
Tectonic movement, mountain building, weathering and erosion
What is released from rocks from weathering and erosion? What happens to it?
Calcium and bicarbonate
Washed into sea and used to form shells
Returned to a rock store when creatures die through sedimentation and burial of organic and inorganic carbon compounds
How many tonnes of carbon move through geological cycle annually
10-100 million tonnes of carbon annually
How is carbon released to the atmosphere from the lithosphere
-released during subduction
- Emitted in volcanoes outgassing
Describe chemical weathering
Atmospheric co2 combines with water vapour to form weak carbonic acid
- acid dissolves rocks and released calcium and other minerals
What is outgassing
To release or give off a gas
What is sedimentation
Process of settling or being deposited as sediment
What is precipitation in carbon
Causes a substance to be deposited in solid form from a solution
How do humans influence geological carbon cycle
Temperature increase from climate change Accelerates chemical weathering process
Poor land practice increase erosion rates - adding more carbon to rivers which can be deposited on the ocean floor where sedimentation occurs
How does negative feedback work in rebalancing the carbon cycle
Increased volcanic activity means increase in co2 emissions and loss of carbon from rocks
Temperature rises so more uplift of air, more rain
So more chemical weathering and more ions deposited on ocean floors
So more carbon stored in rocks
How and why do carbon fluxes vary between day and night?
During the day fluxes are positive from the atmosphere to the ecosystem due to photosynthesis
At night it’s negative as plants respire rather than photosynthesise
which land based eccosystem sequesters the most carbon, and what % does it sequester
The Amazon rainforest sequesters 17% of all terrestrial carbon
more than any other land based biome
Why is the Amazon so significant in carbon;sequestration
Intense sunlight and dense vegetation so efficient photosynthesis
Warm, moist climate leads to rapid decomposition and absorption by roots fixing carbon in the biomass of plants and trees
Why do carbon fluxes vary seasonally ?
Bulk of terrestrial ecosystems are in the northern hemisphere
Atmospheric co2 concentration rises in the northern hemispheres winter as leaves decay and less co2 being sequestered during photosynthesis
How much of global carbon is being stored in the soil
20%-30%
What is the ratio sequestration of carbon in soil compared to other sources
Soil sequesters :
- 2x more than the atmosphere
- 3 x more than terrestrial vegetation
What are the 2 sources of carbon in soils
Organic - plants photosynthesis and store carbon, transfer carbon to soil when they die and decompose
Inorganic - developed in limestone- found in arid soils
How much carbon is humus made up of
60%
Where does the majority of carbon cycling and formation occur in soil
Topsoil - lower down in permafrost regions
What factors explain variations in hue biological carbon store of soil
Climate - arid soils store much less carbon than in colder regions
Soil type - fly rich soils have higher carbon content than sandy soils
Management and use of soils - soils have lost carbon due to disturbance and land use change
How much do arid soils store compared to colder soils
Arid - 30 tonnes per hectare
Colder - 800 tonnes per hectare
What is a carbon balance
The difference between co2 uptake by ecosystems thorough photosynthesis and co2 lost to the atmosphere by respiration
Why are wetland biomes such significant carbon sinks
Wetlands constant path which is a large carbon store having stored carbon for thousands of years
Why might slash and burn upset the carbon balance in soil
Reduced interception leads to greater leaching of carbon
Erosion of humus rich topsoil
Net carbon loss from the soil to the atmosphere
How does the burn part of slash and burn have varying effects on the carbon balance
Burning vegetation releases carbon into atmosphere
By pyrogenic carbonaceous matter accumulates in soil from forest fires
How does anthropogenic climate change leading to thawing of permafrost upset the carbon balance in soil ?
Rising temperatures
Melting of permafrost
Releases trapped methane into the atmosphere
How many times greater a store of carbon is the ocean compare to the atmosphere
50x
What % of oceanic carbon is stored in undersea algae, plants and coral?
93%
What % of carbon is in dissolved form?
7%
What is the oceans net gain of carbon per year
1.2Gtc per year
What are the three main types of carbon cycle pumps
- biological pump
- carbonate pump
- physical pump
Where are the highest chlorophyll concentrations (where tiny surface dwelling ocean plants thrive)
Cold polar waters
Or places where ocean currents bring cold water to the surface (eg equator or continental shores)
Why are there often more phytoplankton in colder regions
Cool temperatures are a sign that water has welled up to the surface from deeper in the ocean
Carrying nutrients that have built up over time
Why is there a phytoplankton bloom in summer months
Nutrients accumulate in dark winter months when plants can’t grow
Plants flourish in wprimg and summer when sunlight returns
Why are phytoplankton important in the carbon cycle
Phytoplankton abundant so represent 50% of earths biomass
Photosynthesise on a vast scale, so constantly sequester carbon dissolved in water
When consumed or die, carbon transferred through food web and released back into atmosphere as consumers respire
Or descend to ocean floor and stored in sediment
What is the carbon pump
Marine organisms such as coral, oysters and lobsters utilise calcium carbonate to make hard shells and skeletons
When organisms die, shells either dissolve (co2 dissolves in water) or sink to bottom and accumulate
Limestone sediment forms
How does carbon return to the atmosphere from the carbonate pump
Limestone sediment is subducted at plate boundaries
Returns to the atmosphere through eruption and outgassing
What is Thermohaline circulation
A conveyor belt of ocean currents that helps shift carbon in the biological and carbonate pumps between the surface and deep ocean
Why is there a large spacial difference of co2 concentrations in the ocean
Co2 mixed much more slowly in the ocean to the atmosphere
Explain the physical pump
Cold water absorb co2 from the atmosphere and warm waters release it
Cold water denser so sinks, conveyor belt moves towards tropics
Water warms and rises at tropics, Tavel back to the poles
Carbon distributed across the ocean
Which major ocean currents transfer carbon through the physical pump from tropics to poles
Gulf Stream current
Why does upwelling happen in cold regions?
Upwelling currents, turbulence from surface winds
Why does the main current of thermohaline circulation begin in the poles
Accumulation of sea ice mains salt concentration increases
Combination of cold and salt means water becomes denser and sinks
Deep ocean conveyor belt created
How does upwelling influence sequestration of carbon
Upwelling releases nutrients to surface
Algal bloom
Greater sequestration of carbon happens through biological pump
How is greenhouse gas naturally released to the atmosphere ?
Evaporation adds water vapour
Animals and plants respire to release co2
No2 released by processes in soil
Swamps release methane
Volcanic eruptions release all
How does the natural greenhouse effect work?
The sun emits shortwave radiation
Earths surface absorbs solar energy as heat
this heat emitted from earths surface as infrared radiation
Greenhouse gases absorb infrared radiation and trap the heat to increase the temperature of the atmosphere
How much heat is retained by greenhouse gases
16° C
Why is the natural greenhouse effect important?
Life enabling as we couldn’t survive on a planet 16° colder
How much of CO2 mess it ions come from fossil fuels since the 1980s
75%
How do temperature trends influence precipitation levels
As global temp increases so does EVT
so water vapour increases in atmosphere
Areas with highest sun (equator) have highest rainfall and low pressure - sets hadley cell in motion
Which ecosystems absorb the most carbon?
Tropical rainforests and coral reefs
Why do coral reefs absorb so much carbon
The marine equivalent of a rainforest
Shallow warm water ideal for plant growth
Why are there more algal blooms occurring in the arctic
Melting of of arctic sea ice ice means greater expanses of the ocean are now exposed to direct sunlight as seasonal thaws last longer
Increased sunlight means increased photosynthesis of phytoplankton
So more co2 absorbed in arctic
What are features of healthy soil
- provides air, water and nutrients for microorganisms and plants to thrive
- contains more carbon and organic matter
- sequesters carbon
- enables infiltration and percolation to reduce flood risk and risk of soil erosion
- retains moisture to regulate temperature during heatwaves
What is the average age of rocks containing soil and gas
70-100 million years old, coal even older
Why is carbon important in maintaining healthy soils?
Soil health depends on organic matter inputs and outputs- without carbon nutrient and water cycles can’t operate properly
Organic matter supports microorganisms which control the nutrient cycle
Provides porous spaces for infiltration and storage of water which enhance plant growth
