Nutrient cycle
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
Nutrients enter biotic from abiotic through autotrophs
Within biotic, heterotrophs transfer nutrients from organism to organism via feeding
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
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.
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
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:
Measured directly
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:
satellites measuring amount of greenhouse gases in the atmosphere
collect air samples from specific regionsto examine in a lab
Analyse prehistoric atmospheric CO2 content trapped in ice bubbles such as in Greenland or Antarctica.
Explain why accurate measurements of carbon dioxide and methane in the atmosphere are important.
It is important to make observations and collect data regarding carbon based gas levels such as CO₂ and CH4
The information helps scientists understand:
natural processes
monitor human impact
test whether actions to reduce greenhouse gas emissions are working
FF Formation: Coal (4)
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
prokaryotic cells in the domain Archaea
produce methane as a byproduct of their anaerobic respiration
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.
Ocean Acidification Reaction
CO2 diffuses into the ocean, reacting with H2O to form carbonic acid (H2CO3)
Carbonic acid dissociates to form bicarbonate ions and hydrogen ions
Then bicarb ions dissociate further to form CO3 & H+
OA: CaCO3
coral and molluscs absorb CO3- and Ca+ ions to form CaCO3
They use it to build shells and exoskeletons
Can also form limestone
Oxidation of Methane
Methane is released by organisms and is burned as a fossil fuel
When CH4 enters the atmosphere it reacts with oxygen
CH4 + 2O2 → 2H2O + CO2
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
peat is dried out to reduce high levels of humidity
cut into slabs, granules, or blocks
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