The carbon cycle EQ1

Question 1

What are the sour main processes in the biogeochemical carbon cycle?

Answer 1

photosynthesis
Respiration
Decomposition
Combustion

Question 2

What are the four main processes in the geological carbon cycle?

Answer 2

Volcanic out-gassing
chemical weathering
lithification (creating sedimentary rock)
metamorphism

Question 3

Compare the geological carbon cycle and the biogeochemical carbon cycle.

Answer 3

Both are closed systems that circulate carbon between the stores
Bio- short term, living organisms
Geo-long term, non-living processes

Question 4

What are the different spheres of carbon?

Answer 4

Lithosphere - fossil fuels +rocks mainly calcium carbonates
Biosphere_ living and dead organisms
Hydrosphere - dissolved CO2
Atmosphere - CO2 and methane

Question 5

What are the different carbon stores?

Answer 5

Crustal - sedimentary rock
soil- microorganisms break down plant matter
Ocean surface - dissolved CO2 and plankton undergoing photosynthesis
Oceanic deep - dissolved carbon at great depths
Atmospheric - CO2 and methane
Terrestrial ecosystems - plants from photosynthesis

Question 6

Explanation of some key processes in the geological carbon cycle.

Answer 6

Weathering of rocks releases carbon containing compounds.
Plants and animal biomass releases carbon during decomposition.
Rivers transport particles to the ocean where they are deposited.
Over millennia these sediment accumulate and are cemented to form layers of sedimentary rock by the process of lithification
Heat and pressure causes metamorphism.

Question 7

Why are oceans an important carbon store?

Answer 7

One of the worlds largest carbon stores
Store 50 times more carbon that the atmosphere.
93% is stored in algae, plants and coral.
7% in dissolved form.

Question 8

What are the three pumps in ocean sequestration of carbon?

Answer 8

Biological pump
Carbonate pump
Physical pump

Question 9

What are phytoplankton?

Answer 9

Microscopic organisms (plants) that live in watery environments.
They photosynthesis moving carbon from the atmosphere into their biomass as glucose.
They are very sensitive to changes in temperature, sunlight, water depth, wind and nutrient levels.
When populations grow exponentially it is known as a bloom.

Question 10

What is the biological pump in the ocean sequestration of carbon?

Answer 10

Phytoplankton transfer carbon dioxide from the atmosphere to the ocean by photosynthesis.
Carbon is returned to the near surface when phytoplankton decompose but some falls to the ocean depths.

Question 11

How is nutrients cycled in the ocean?

Answer 11

Phytoplankton respire and photosynthesise in the top layer.
Organic material sinks when it dies.
Cold water at the bottom of the ocean rises, this pulls nutrients up to the top layer.
Warmer surface water is preventing cold water up-welling and nutrient cycling, reducing phytoplankton blooms.

Question 12

What is the carbonate pump in the biological sequestration in the ocean of carbon?

Answer 12

Phytoplankton sequester carbon during photosynthesis, contained within their calcium carbonate shells.
Carbon is passed up the food chain to consumers e.g zooplankton. Consumers release carbon back into the ocean surface by the biological process of respiration.
Dead decomposing marine life falls to the bottom of the ocean and undergoes the process of lithification to form sedimentary rocks.

Question 13

What is the physical pump in biological sequestration of carbon in the ocean?

Answer 13

Also known as thermohaline circulation.
Regulates global ocean temperatures and circulates carbon.
Colder water has a higher salt content and density, this causes it to sink pulling in warmer water from tropical areas.

Question 14

Thermohaline circulation evaluation.

Answer 14

+ circulates carbon from upper to deeper waters.
+ensures water is nutrient rich to support food chains.
- One cubic meter takes 1000 years to circulate the whole system.

Question 15

Why is the oceans ability to sequester carbon decreasing?

Answer 15

Oceans uptake = 92PgC annually
Oceans release= 90PgC annually.
Oceans are losing their ability to sequester carbon due to rising temperatures and acidification, poorer conditions for phytoplankton, they decrease in number so accumulate less carbon by photosynthesis.

Question 16

Where do trees get their mass from?

Answer 16

95% of tree biomass is from carbon.
Primary producers - use photosynthesis to create biomass.
Larger Net productivity - more biomass.

Question 17

Name the different biomes.

Answer 17

Tropical Rainforest
Tundra
Desert
Coniferous forest (evergreen)
Deciduous forest
Savanna
Temperate grassland

Question 18

What are the biomes relevant importance as carbon stores?

Answer 18

Boreal Forest- largest carbon store 559 gigatonnes of carbon
Tropical rainforests - second biggest 428 gigatonnes.
Deserts- largest biome by area 4.55bn ha but one of the smallest total carbon stores at 199 gigatonnes.

Question 19

What are the different types of carbon stored in soils?

Answer 19

soils store 20-30% of global carbon.

1. Inorganic carbon - arid and semi-arid soils, often found on limestone, no or very little living material.
2. Organic carbon - dead plants decompose, litter from leaves and dead organic matter, carbon fluxes between the plants and the soil.

Question 20

What are the processes in terrestrial sequestration?

Answer 20

Producers take C out of the atmosphere by photosynthesis.
Carbon is passed up the food chain by consumers.
Micro-organisms and detritus feeders feed on animal waste and dead organic matter, incorporate carbon into their own biomass.
Sabrobionts help decay dead organic matter returning carbon to the soil.
Respiration at all stages releases carbon to the atmopshere.

Question 21

What does a nutrient cycle diagram consist of?

Answer 21

The stores and arrows are proportional to show the dominant processes and biggest stores.

Question 22

How is carbon cycles in the coniferous biome?

Answer 22

Litter is the largest store _ ontinually supplied from needles and is slow to decompose due to cold temperatures.
Soil nutrients is low and thinner
relatively low store in biomass, conifers only form one layer, block sunlight preventing smaller plants in the undergrowth.

Question 23

Tropical rainforest Nutrient cycling notes.

Answer 23

Large biomass - high biodiversity due to climate
Small litter - climate means there is no shedding season so little input, decomposition is rapid due to heat, high precipitation washes litter away.
Soil quality is poor - high precipitation causes soil erosion and leaching so the soil is very thin.

Question 24

Different types of soil, carbon statistics.

Answer 24

Humus soils are the most fertile, they contain 60% carbon, sequester carbon and store water as soil moisture.
In permafrost region over 61% of carbon is stores deeper than 30cm, ancient carbon stores.

Question 25

What factors affect soils capacity to store carbon?

Answer 25

Climate - higher temperatures and not waterlogged conditions increases decomposition rates. Rainfall increases plant growth to decay.
Arid soils stores 30 tonnes of carbon per hectare, cold regions store 800 tonnes per hectare.
Soil type_ clay rich soils have a higher carbon content because there is a slower rate of decompostion
Management - soils have lost between 40-90bn tonnes of carbon since 1850 due to human cultivation and activity disturbing the top soil layers.

Question 26

Why are mangroves important?

Answer 26

Mangroves are found along tropical and subtropical coasts, they sequester 1.5 metric tonnes of carbon per hectare every year.
They support a thick organic layer of soil, litter is partially submerged, these anaerobic conditions slow decomposition, little respiring bacteria so carbon is stored.

Question 27

How does tundra soils store carbon?

Answer 27

The majority of the soil is frozen - ancient carbon stores are kept beneath the permafrost layer.
Microbe activity only occurs in the surface layer when it thaws, releasing small amounts of carbon to the atmosphere.
More carbon is being released as the permafrost melts due to anthropogenic climate change.
The permafrost currently stores 1,400 gigatonnes are carbon.

Question 28

Why are peatlands important at storing carbon?

Answer 28

Peatlands are a type of wetland, they cover 3% of the global land surface.
Water logged conditions slow decomposition, dead plants accumulate storing carbon.
Stores carbon for thousands of years.
If peat soil is continually exposed to heat, pressure as it is compressed it will eventually form coal.
Mainly intropical areas.

Question 29

What role does the Himalayas play in the carbon cycle?

Answer 29

Is one of the earths largest terrestrial carbon stores.
Started as oceanic sediment rich in calcium carbonate, underwent lithification to form sedimentary rock.
Folded up by mountain building and tectonic movement to be above sea level.
The Himalayas are actively weathered, the material is transported back to the oceans by rivers where it dissolves.

Question 30

Explain how sedimentary rock is formed?

Answer 30

Eroded material and dead organic matter sinks to the bottom of the ocean.
Organic material starts to decay, some carbon-containing material remains.
Over millions of years new sediment builds up forming layers, this applies heat and pressure.
Eventually, sediment is compressed and cemented undergoing the process of lithification forming sedimentary rock.

Question 31

what is the role of chemical weathering in the carbon cycle?

Answer 31

in the atmosphere, water reacts with CO2 to produce carbonic acid.
Acid rain dissolves calcium ion in rocks.
These are transported to the sea and combine with bicarbonate to form calcium bicarbonate and calcite.
Deposition turn caclite into carbon containing sediment.

Question 32

What is volcanic outgassing?

Answer 32

Mainly occurs at subduction zones, at mid-ocean ridges.
Most of the CO2 released is derived from the metamorphism of carbonate rocks subducted in the ocean crust at these subduction zones.
A slow a constant amount of C02 is released, this happens faster and in higher quantities when volcanoes erupt.
This removes carbon from ancient sedimentary stores.

Question 33

What is the greenhouse effect?

Answer 33

Short wavelength solar radiation reaches Earth surface from the sun.
Some of this radiation is reflected back into space, letting heat escape from the earths atmosphere.
Some is reflected from the earths surface and absorbed by greenhouse gases, these re-emit heat to the earths surface.
This has a warming effect, beneficial to ensuring Earth is warm enough to support life.

Question 34

How is the enhanced greenhouse effect different to the normal greenhouse effect?

Answer 34

Increased greenhouse gas concentrations from human activity such as burning fossil fuels during the industrial revolution.
Less long wavelength radiation is reflected to space.
More is absorbed and re-emitted by greenhouse gases, this causes an unnatural rise in global temperatures (anthropogenic climate change)
Global temperatures increased by 1 degree in the last decade.

Question 35

What is the relative importance of each greenhouse gas?

Answer 35

CO2 - is the most abundant gas at 378ppm but has the lowest warming potential.
CF4 and CF6 - concentration doubled during the industrial revolution (still one of the lowest) but has a very high warming effect of 5,700 and 22,200 GWP.
CH4 and N2 - stronger warming effect than CO2 at 23GWP and 296 GWP.

Question 36

How much have CO2, CH4 and N2 levels increased since 1850?

Atmospheric concentrations.

Answer 36

CO2 - 30% since 1850
CH4- 250% since 1850
N20 - 16% since 1850.

Question 37

How are global temperatures expected to change because of anthropogenic climate change?

Answer 37

Global increased.
A larger increase on land rather than ocean temperatures. Europe and Canada will increase by an average of 6 degrees by 2090.
Polar regions will have the largest increase due to melting ice decreasing the albedo effect.

Question 38

How is global rainfall expected to change due to anthropogenic climate change?

Answer 38

Split trend.
Northern Europe + central North America have an increase of 5mm yr-1 per decade.
Sahara, southern Europe, west coast of Africa will have a decrease of 10mm yr-1.
Exaggerate pressure systems, widen differences in water surplus and water deficit.
Increased risk of flooding and desertification.

Question 39

What will be the impacts of increased atmospheric carbon be on climate?

Answer 39

Carbon dioxide is a greenhouse gas.
Enhanced greenhouse effect - global warming.
Changin rainfall patterns
Increase in storm intensity.
Wider inequality in water security.

Question 40

What are the implications of increased concentrations of atmospheric carbon on ecosystems?

Answer 40

Arctic region will warm twice as fast as the global average, due to reduced albedo effect.
Coniferous Forest biome will grow northwards as tundra melts.
Decrease in biodiversity, extinction will be more common, red fox migrates north, competes with the Arctic fox.
Marine ecosystems e.g coral and tundra ecosystems are the most vulnerable to changes in temperature.

Question 41

What effect does increased atmospheric carbon have on the hydrological cycle?

Answer 41

Less precipitation as snow - reduce the size of Alpine glaciers which are used as a summer water source in Europe.
Droughts in the Mediterranean and West Africa - due to decreased rainfall and higher rates of evaporation.
Heavy precipitation events such as storms and cyclones will increase in intensity particularly in the North Atlantic.
General: warmer earth, more evaporation, more condensation, change precipitation trends,

Question 42

What are tipping points and feedback loops?

Answer 42

Tipping point - when the effects of anthropogenic climate change becomes irreversible.
Positive Feedback loop - amplifies global warming.
Negative feedback loop - reduces global warming.

Question 43

Positive feedback loop example.

Answer 43

Burning fossil suels, increase atmopsheric CO2, enhanced greenhouse effect, higher average temperatures,
Glaciers and ice melt so reduced albedo effect, increases temp
Permafrost melts, releases ancient carbon stores, increased atmospheric CO2.

Question 44

Negative feedback loop example.

Answer 44

Increased Co2, rise in global temperatures.
tundra ice melts.
coniferous forest biome grows
Absorbs CO2 by photosynthesis.
Flux of carbon from the atmosphere to terrestrial stores.