Carbon edexcel a level geography

what is the biogeochemical cycle

includes the carbon, hydrological and nitrogen cycle - these are natural processes that recycle nutrients in various chemical forms from the environment, to organisms, and then back to the environment.

- The carbon cycle is only one of these biogeochemical cycles and can be defined as

- the exchange of carbon between its four main reservoirs: the atmosphere, terrestrial biosphere, oceans and sediments.

the carbon stores (6)

- Biosphere, Trees, plants and all other living organisms

Carbohydrates, 560bn metric tonnes, 0.0012%

- Atmosphere, In greenhouse gases, Carbon dioxide and compounds methane (greenhouse gases), 750 billion metric tonnes, 0.0017%

- pedosphere, Soils e.g. Pete contains 60% carbon, Organic matter from dead materials, 65,500 billion metric tones, 0.0031%

- Fossil fuels, Organic matter deep in the ground or in natural reservoirs, Oil, coal, gas and hydrocarbons

4,000 billion tonnes, 3 - 8% of the lithospheres 99.9%

- hydrosphere, Found in all bodies of water. 90% is dissolved as bicarbonate in sea water, Dissolved co2, bicarbonate ions and carbonate ions. 38,000 billion metric tonnes, 0.0038%

- lithosphere, Marine sediment and sedimentary rocks

Limestone - made up of shells of sea creatures from millions of years ago, 66 - 100 million metric tonnes

99.9%

key term and concept - carbon cycle and systems feedback

carbon cycle; the biogeochemical cycle where carbon moves from one sphere to another.

- closed system made up of linked subsystems that have inputs, throughflows and outputs.

- Carbon stores function as sources (adds carbon to the cycle) and sinks.

It is systems feedback that determines the balance of the carbon cycle e.g. if sources = sinks the system is in equilibrium. It can take hundreds of years to return to balance.

what are the three forms of carbon in the cycle

- Inorganic - rocks

- Organic - plants

- Gaseous - methane

what is carbon sequestration

the natural storage of carbon by physical or biological processes such as photosynthesis.

- carbon sequestration is the transfer of carbon form the atmosphere to other stores both natural and artificial.

how does volcanic activity contribute to the composition of the atmosphere

In the Precambrian geological period volcanic activity added carbon dioxide, water and sulphur dioxide to the atmosphere rapidly - this formed the basic composition of the atmosphere today

What percentage of carbon is stored in sedimentary rocks, such as limestone, sandstone and shale?

Most of earths carbon is geological which resulted in the formation of sedimentary carbonate rocks in the Ocean. Biologically derived carbon in rocks such as shale and coal.

99.9% of earth carbon is stored in the lithosphere that is made up of sedimentary rocks.

how was carbon stored during the Carboniferous period and for how long?

In the Carboniferous period the earth established its current carbon cycle, predominantly the carbon was stored in fossil fuels and limestone.

Why are limestone, shale and fossil fuels important carbon stores?

Their formation locks away vast amounts of carbon for long periods of time, this is from carbon sequestered over millions of years through geological processes.

how sedimentary carbonate rocks are formed?

Shell building organisms and Plankton are precipitated onto the ocean floor forming layers which cementsthem together. This causes them to become lithified (becomes a rock) into limestone. This forms the 80% of today's carbon containing rocks. The other 20% is from organisms that have organic carbon in, this is formed from them becoming embedded in layers of mud and over millions of years heat and pressure compress the mud and carbon to make sedimentary rocks like shale.

how are fossil fuels formed?

the remains of organic material over 300 million years ago. When organic matter builds up faster than it can decay, the layers of organic carbon develop into coal, oil or natural gas instead of shale.

What role does the water cycle play in the carbon cycle?

key driver

e.g. run-off into rivers transport eroded rock and soil into the oceans

explain diagenesis of sedimentary rocks

Carbon is stored during the diagenesis - the physical and chemical changes occurring during the conversion of sediment to sedimentary rock - of sedimentary rocks. When the remains of organic material (sediment) from what used to be dead organisms, sinks to the bottom or rivers and seas. They then become covered in silt and mud so decay anaerobically over a millennium. If this organic matter builds up faster than it can decay the layers of organic carbon become coal, oil or gas (fossil fuels).

what is the geological cycle

the slow part of the carbon cycle, centred on huge carbon stores in rocks and sediments. Reservoir turnover of 100,000 years. Buried organic matter takes millions of years to become fossil fuels. Carbon is more quickly exchanged via volcanic eruptions.

KEY CONCEPT - geological fluxes

small annual basis, without carbon stored in rocks would accumulate and remain there forever, this would eventually deplete sources of carbon dioxide needed for all life forms.

e.g. chemical weathering or volcanic outgassing

the 5 processes in geological cycle

1. Mechanical, chemical and biological weathering -

Mechanical breaks up rocks due to frost the shattering produces small transportable particles.

Chemical breaks down rocks from carbonic acid in rain that dissolves carbonate-based rocks

Biological is when animal and the roots of plants break rocks up

2. Decomposition - plant and animal particles from decomposition after death and surface erosion store carbon

3. Transportation - rivers carry particles as ions to the ocean then deposits them

4. Sedimentation- deposited sediment accumulates burying older sediment below e.g. shale

5. Metamorphosis - Pressure builds due to plate tectonics in the layers of sediment which eventually leads to deeper sediment changing to rock e.g. limestone becomes marble.

explain chemical weathering

chemical weathering of carbon-rich rocks such as limestone. Rainwater is a carbonic acid as it absorbed CO2 from the air. This then dissolves rock minerals to form new minerals (calcium carbonate). Shell building organisms and Plankton are precipitated onto the ocean floor forming layers which cements them together. This causes them to become lithified (becomes a rock) into limestone. This forms the 80% of today's carbon containing rocks. Tectonic forces may bring carbon-rich sedimentary rocks into contact with extreme heat, which causes chemical changes and the release of CO 2 back into the atmosphere.

explain volcanic outgassing

there is co2 in the earth's crust and volcanic eruptions and earthquakes allows some of this c02 to be released. Outgassing occurs at

- Active and passive volcanic zones (subduction zones and spreading ridges)

- Places with no current volcanic activity e.g. hot springs or geysers (Yellowstone USA)

- Direct emissions from fractures in earth's crust

Currently volcanoes emit 0.15 to 0.26 Pg/yr.

Philippines 1991 eruption of Mt Pinatubo - degassing pulse, it is part of an island arc due to a subduction zone. These huge eruptions produce fresh silicate rock that starts the carbon cycle again.

biological carbon cycle - fast

operates at terrestrial, oceanic and atmospheric levels

the cycling of carbon between the earth surface and the atmosphere is the fast cycle. Movement of carbon from living things up into the atmosphere - respiration and decomposition.

100 to 1000x more carbon than the geological carbon cycle

photosynthesis (fluxe of biological carbon cycle)

Plants are primary producer organisms, absorb carbon dioxide from the atmosphere and use energy from the sun to convert it into carbohydrates like glucose. This releases oxygen as a biproduct. In oceans microorganisms called phytoplankton do the same thing.

respiration (fluxe of biological carbon cycle)

this process balances photosynthesis - produces energy by combining oxygen with carbohydrates and releasing carbon dioxide and water.

decomposition (fluxe of biological carbon cycle)

When plants and animals die and decompose, bacteria and fungi break down the carbohydrates. - decomposition. This releases carbohydrates and methane back into the atmosphere. Some of this carbon is transferred into the soil in the form of humus, here there are millions of microorganism's part of the carbon cycle.

biological carbon pump

- oceanic organic sequestration of CO2 to oceans by phytoplankton (single cell microorganism plants floating at the sea surface to absorb sunlight and photosynthesis, this makes up the base of the food-chain.) rapid growth rates in shallow continental shelves where nutrients from rivers is rich, (nutrient upwelling locations) e.g. The Artic and Southern Oceans. Carbon is passed up food chain by consumer fish - releases CO2 back into water and atmosphere.

These phytoplankton sequester over 2 billion metric tonnes of CO2 annually

0.01% of the carbon reaches sea floor as the dead organisms on the seabed floor causes carbonate material on the seabed to accumulate on the seabed and eventually turn into sedimentary rock. These ocean seabed's are also a source of methane gas in shallow offshore areas, into the atmosphere.

carbonate pump

- inorganic carbon sedimentation. Marine organisms utilise calcium carbonate for shells as organism die and sink lots of their shells dissolve before reaching the seabed floor. This carbon becomes part of the deep ocean currents - shells that don't dissolve build up over time on the seabed floor forming limestone sediments e.g. dover white cliffs.

physical pump

based on oceanic circulation of water including upwelling, downwelling and thermohaline current. CO2 mixes slower in oceans than the atmosphere causing large spatial differences in CO2 concentration. Colder water = more CO2 absorbed, and in deep oceans CO2 is 10% higher. The warmer tropical waters release CO2 and the colder high-latitude oceans take in CO2 from the atmosphere. Double the amounts of CO2 can dissolve into cold oceans compared to warm. Deep cold oceans have sinking water due to their density, this accumulates CO2 from the surface and takes it down.

Thermohaline meaning

thermo - temperature

haline - salinity

thermohaline circulation

- deep conveyor pump in ocean

Warm surface waters have less nutrients and CO2 but are enriched as they travel through the conveyor belt as bottom layers. The foundation of nature's food chain depends on the support of nutrient-rich waters that support algae and seaweed. This circulation helps shift carbon in the carbonate pump from upper to deeper waters.

What are the 5 distinct phases in the circulation of the thermohaline conveyor belt?

1. main current begins in polar regions. Water is cold, sea ice forms and surrounding seawater becomes saltier increasing its density causing it to sink.

2. Current is recharged as it passes Antarctica by the cold, deep, salty, dense water

3. Main current divides: north into Indian Ocean and into Western Pacific.

4. Both branches warm and rise as they travel northwards, looping back into the southward and westward.

5. Newly warmed surface waters continue circulating around the globe. When they return to the Atlantic, they cool and the cycle repeats.

oceanic carbon cycle

one of the main sinks is the Ocean, they store 50 x greater than that of the atmosphere, 93% of carbon is stored in undersea algae, plants and coral and the rest in dissolved form.

Carbon is stored here as dissolved CO2 in the water and carbon compounds in marine organisms.

The input to the ocean store is absorption via a gas exchange with the atmosphere. Carbon is transferred through precipitation of acid rain. Most of the carbon in this cycle is on the floor of shallow oceans (sink) as accumulating sediments of dead and decaying marine organism remains.

The colder, deeper (more pressure) Southern Antarctic Ocean hold more gas - carbon sink. The Southern Ocean accounts for 25% of CO2 diffusion from the atmosphere to the oceans. As deep cold water gradually rises to the surface absorbing co2 from the atmosphere.

terrestial carbon cycle

Based on organic carbon, has the shortest temporal scale - seconds / minuets.

Primary producers - plants, photosynthesis, taking carbon from atmosphere, release CO2 back into atmosphere via respiration.

Consumers eat plants, carbon then becomes part of their fats and proteins.

Micro-organisms and detritus feeders feed on waste material from animals, this becomes part of the micro-organisms

After plant and animal death tissues like leaves decay faster than resistant structures like wood. Decomposition is fastest in tropical rainforests with high rainfall, temperature and oxygen levels. Slowest in dry cold conditions with less oxygen.

The two key carbon sinks are tropical rainforests and wheatlands/peatlands.

why do carbon fluxes vary?

on a temporal scale:

· Diurnally - in daytime the fluxes are positive from the atmosphere to eh ecosystem but at night they are negative with loss from the ecosystems to the atmosphere

· Seasonally - in the northern hemisphere winter, when few land plants are growing and many are decaying, atmospheric CO2 concentrations rise, in the spring plants begin to grow again so concentrations drop.

Fast cycle

A rapid process in the carbon cycle.

Slow cycle

A gradual process in the carbon cycle.

Biosphere

Trees, plants and all other living organisms; holds carbon in carbohydrates with 560 billion metric tonnes, accounting for 0.0012% of all carbon on Earth.

Atmosphere

Contains greenhouse gases like carbon dioxide and methane; holds 750 billion metric tonnes, accounting for 0.0017% of all carbon on Earth.

Pedosphere

Soils, e.g., peat, which contains 60% carbon; holds 65,500 billion metric tonnes, accounting for 0.0031% of all carbon on Earth.

Fossil fuels

Organic matter deep in the ground or in natural reservoirs; includes oil, coal, gas, and hydrocarbons; holds 4,000 billion tonnes, which is 3-8% of the lithosphere's carbon.

Hydrosphere

Found in all bodies of water; 90% is dissolved as bicarbonate in seawater; holds 38,000 billion metric tonnes, accounting for 0.0038% of all carbon on Earth.

Lithosphere

Marine sediment and sedimentary rocks; limestone made up of shells of sea creatures from millions of years ago; holds 66-100 million metric tonnes, accounting for 99.9% of the lithosphere's carbon.

Biogeochemical cycles

Natural processes that recycle nutrients in various chemical forms from the environment to organisms and back.

Carbon cycle

The exchange of carbon between its four main reservoirs—the atmosphere, terrestrial biosphere, oceans, and sediments.

IPCC

Intergovernmental Panel on Climate Change, the leading international organization for scientifically assessing climate change.

Anthropogenic

Processes and actions associated with human activity.

Petagrammes/gigatonnes

Units used to measure carbon; one petagram (Pg) or gigatonne (Gt) is equivalent to one trillion kilograms.

Reservoirs or sinks

Entities that remove carbon from the atmosphere.

Carbon pathway

Also known as the carbon cycle; a closed system made up of linked subsystems that have inputs, throughflows, and outputs.

Carbon store

A sink that takes in more carbon than it gives out.

Carbon source

A source where the output is greater than the input.

Surface layer (euphotic zone)

Oceanic store with 900 GtC.

Intermediate (twilight zone) and deep ocean layer

Oceanic store with 37,100 GtC.

Living organic matter

Oceanic store with 30 GtC.

Dissolved organic matter

Oceanic store with 700 GtC.

Carbon emissions reduction statistics

In the UK, carbon emissions fell by 31%, and 28% in Australia, marking the biggest annual drop since WWII.

Net zero emissions

The target to meet the Paris Agreement by mid-century.

Forms of carbon in the carbon cycle

Inorganic (rocks), Organic (plants), Gaseous (methane).

Carbon Sequestering

The natural storage of carbon by physical or biological processes such as photosynthesis.

Carbon Sequestration

The transfer of carbon from the atmosphere to other stores, both natural and artificial.

Origin of Carbon

Carbon comes from the earth's interior, mostly formed when carbonate rocks undergo metamorphosis.

Volcanic Activity

Contributes to the composition of the atmosphere by adding carbon dioxide, water, and sulphur dioxide rapidly.

Sedimentary Rocks

Most of earth's carbon is geological, resulting in the formation of sedimentary carbonate rocks in the ocean.

Biologically Derived Carbon

Carbon found in rocks such as shale and coal.

Lithosphere Carbon Storage

99.9% of earth carbon is stored in the lithosphere, which is made up of sedimentary rocks.

Carboniferous Period

A time when the earth established its current carbon cycle, predominantly storing carbon in fossil fuels and limestone.

Importance of Limestone, Shale, and Fossil Fuels

Their formation locks away vast amounts of carbon for long periods through geological processes.

Figure 2.2

Shows carbon stores and fluxes, with the largest store being sedimentary rock at 83,000,000 PgC.

Marine Biota Carbon Store

The smallest carbon store at 3 Pg/yr.

Rock Weathering Input

Contributes 0.4 Pg/yr to the carbon cycle.

Atmospheric Ocean Input

Contributes 80 Pg/yr to the carbon cycle.

Photosynthesis Input

Contributes 123 Pg/yr to the carbon cycle.

Respiration and Fire Output

The largest output of carbon at 118.7 Pg/yr.

Volcanic Eruptions Output

The lowest output of carbon at 0.1 Pg/yr.

Human Activity Impact

Causes a 240 Pg change to the atmosphere's store of carbon.

Formation of Sedimentary Carbonate Rocks

Shell building organisms and plankton precipitate onto the ocean floor, forming layers that become lithified into limestone.

Water Cycle's Role in Carbon Cycle

The oceans act as a store for carbon, transporting it back to the oceans as ions in rivers.

Diagenesis

The physical and chemical changes occurring during the conversion of sediment to sedimentary rock.

Calcareous Ooze

Calcium carbonate mud formed from the hard parts of the bodies of free-floating organisms.

Calcareous Ooze Location

Highest in the Atlantic Ocean, not found near the Arctic or Antarctic oceans.

Long-Term Carbon Cycle

Takes 100 - 200 million years.

Chemical Weathering

Breaks down rocks from carbonic acid in rain that dissolves carbonate-based rocks.

Sequestration

Process of carbon removed from the atmosphere and stored in liquid or solid form.

Volcanic Emissions

Volcanoes release over 200 million tonnes of carbon dioxide into the atmosphere each year.

Geological Carbon Cycle

The slow part of the carbon cycle, centred on huge carbon stores in rocks and sediments.

Reservoir Turnover

100,000 years.

Mechanical Weathering

Breaks up rocks due to frost, producing small transportable particles.

Biological Weathering

Occurs when animals and the roots of plants break rocks up.

Decomposition

Plant and animal particles from decomposition after death and surface erosion store carbon.

Transportation

Rivers carry particles as ions to the ocean and then deposit them.

Sedimentation

Deposited sediment accumulates, burying older sediment below, e.g., shale.

Metamorphosis

Pressure builds due to plate tectonics in sediment layers, leading to deeper sediment changing to rock.

Chemical Weathering of Carbon-Rich Rocks

Rainwater as carbonic acid absorbs CO2 from the air and dissolves rock minerals to form new minerals.

Volcanic Outgassing

CO2 in the earth's crust is released through volcanic eruptions and earthquakes.

Active Volcanic Zones

Locations where outgassing occurs, such as subduction zones and spreading ridges.

Passive Volcanic Zones

Places with no current volcanic activity, e.g., hot springs or geysers.

Direct Emissions

CO2 released from fractures in the earth's crust.

Current Volcano Emissions

Volcanoes emit 0.15 to 0.26 Pg/yr.

Hydrogenous Deposits

Majority found in the North Pacific Pelagic.

Carbonic Acid

Produced when carbon dioxide combines with water vapour, making rainfall slightly acidic.

Fossil Fuels Formation

Trapped organic matter in sediment is converted into coal, oil, and gas over millions of years.

Philippines 1991 eruption of Mt Pinatubo

A significant volcanic event that is part of an island arc due to a subduction zone, producing fresh silicate rock that restarts the carbon cycle.

Fossil fuels burning

A human activity that releases carbon dioxide into the atmosphere, contributing significantly to the carbon cycle.