Carbon Cycle: 4.3

Nutrient cycle

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The circular movement and exchange of matter through an ecosystem, from abiotic to biotic and back.

Nutrients

chemicals that are needed for the maintenance of life

Steps of nutrient cycle

1. Nutrients enter biotic from abiotic through autotrophs
2. Within biotic, heterotrophs transfer nutrients from organism to organism via feeding
3. Nutrients return to abiotic from biotic e.g. CO2 from cell respiration moves back into the atmosphere

Carbon Cycle

Exchange of carbon among the biosphere, pedosphere, geosphere, hydrosphere & atmosphere of Earth.

Carbon cycle: Pools

Location or system that can store or release carbon.

Pools: (1) Atmosphere

Carbon is found in the form of CO2 and Methane therefore presence of carbon in the atmosphere influences greenhouse effect & climate change.

Pools: (2) Pedosphere

Carbon is found in the form of soil which is a mixture of organic matter, minerals that support life

Pools: (3) Biosphere

portion of the Earth with living material which stores carbon within biological molecules where living matter includes plants, animals, & microorganisms

Pools (4) Hydrosphere

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Dissolved inorganic carbon in the Earth’s water, mostly in the oceans.

Pools: (5) Geosphere

Lithosphere where carbon is stored as sedimentary rocks within the planet’s crust. Rocks are derived from hardening mud, CaCO3 particles, or shells into limestone

Pools: (6) Fossil Fuels

A "fossil" store of **organic** matter e.g. coal, oil, natural gas, formed over millions of years. Through human actions this carbon is introduced into the other carbon pools unnaturally.

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Flux

Process that exchange carbon between pools. Where even a single carbon pool may have multiple fluxes adding and removing carbon simultaneously.

Flux: (1) Photosynthesis

Autotrophs photosynthesise, removing carbon and using it within plants, moving it to the biosphere. Transfer From **atmosphere/hydrosphere to biosphere**.

Flux: (2) Respiration

All organisms in biosphere or pedosphere release carbon dioxide into the atmosphere through cell respiration. Therefore **pedosphere/biosphere to atmosphere**

Flux: (3) Decomposition

CO2 released from the biosphere into the atmosphere by cell respiration by decomposers. Breakdown of complex compounds such as faeces & dead orgs into simpler carbon compounds transfers from **biosphere to pedosphere/atmosphere.**

Flux: (4) Diffusion

Inorganic compounds are absorbed and released within the **hydrosphere and atmosphere** through diffusion.

Flux: (5) Lithification

process in which sediments compact under pressure, expel fluids, and gradually become solid rock. Transfers carbon from **pedosphere/biosphere (shells) to the geosphere**

Flux: (6) Combustion

Forest fires & fossil fuel combustion release CO2, moving carbon from the **biosphere to the atmosphere.**

Flux: (7) Fossilisation

Dead organisms decay minimally in anaerobic conditions, when they build up over millions of years, they form fossil fuels. Carbon moves from **pedosphere/biosphere to geosphere**

Flux: (8) Feeding - Technically not

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heterotrophs moves carbon within biological molecules along the food chain through eating, within the biosphere

Carbon Cycle Diagram, draw then check

Carbon flux values are:

1. Measured directly
2. Extrapolated from data using mathematical models

Outline how data on the concentration of atmospheric carbon dioxide and methane are collected. (3 points)

Scientists measure the amount of carbon based gases through:


1. satellites measuring amount of greenhouse gases in the atmosphere
2. collect air samples from specific regionsto examine in a lab
3. Analyse prehistoric atmospheric CO2 content trapped in ice bubbles such as in Greenland or Antarctica.

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**Explain why accurate measurements of carbon dioxide and methane in the atmosphere are important.** 

1. It is important to make observations and collect data regarding carbon based gas levels such as **CO₂ and CH4**
2. The information helps scientists understand:

* natural processes
* monitor human impact
* test whether actions to reduce greenhouse gas emissions are working

FF Formation: Coal (4)

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* hard sedimentary rock
* can be burned as fuel
* C, O, N, S
* formed from peat through heat & pressure

FF Formation: Oil & Natural Gas (6)

* prehistoric orgs held carbon in their bodies
* when they died they sank to bottom of sea
* millions of years, sediment formed but lipid kerogen remained
* deeper they sank, more heat & pressure
* amount of pressure, heat, and type of biomass determines gas or oil.
* oil or gas then accumulates in pores around rock in process **lithification**

Methanogenic Archaea Examples

* occupy landfills and other soils, & ruminants e.g. cow
* sediments below the seafloor and the bottom of lakes.
* Rice fields also generate large amounts of methane during plant growth

Methanogenic Archaea - DEF

1. prokaryotic cells in the domain Archaea
2. produce methane as a byproduct of their anaerobic respiration
3. Methane is oxidized in the atmosphere to form CO2 and H2O.

Seasonal CO2 Fluctuations

* result of photosynthetic activity by plants
* Decrease in CO2 is due to high photosynthetic activity by plants in spring & summer
* Increase in CO2 is due to plant dormancy and less photosynthesis in winter, and increased respiration by other orgs.

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Ocean Acidification Reaction

1. CO2 diffuses into the ocean, reacting with H2O to form carbonic acid (H2CO3)
2. Carbonic acid dissociates to form bicarbonate ions and hydrogen ions
3. Then bicarb ions dissociate further to form CO3 & H+

OA: CaCO3

1. coral and molluscs absorb CO3- and Ca+ ions to form CaCO3
2. They use it to build shells and exoskeletons
3. Can also form limestone

Oxidation of Methane

1. Methane is released by organisms and is burned as a fossil fuel
2. When CH4 enters the atmosphere it reacts with oxygen




3. CH4 + 2O2 → 2H2O + CO2
4. This releases CO2

Peat

* heterogenous mixture of dead organic material, moss and histosol
* anaerobic conditions created due to high levels of water, non-decomposed material accumulates
* pH very acidic, and takes hundreds of years to form
* non-renewable

Peat as a fossil fuel

1. peat is dried out to reduce high levels of humidity
2. cut into slabs, granules, or blocks
3. burned

Biosequestration

process of removing carbon from the cycle/environment then trapping carbon within limestone, such as the tiny shells of foraminifera. However this limestone is used in cement, and when used releases CO2 back into the atmosphere