Carbon Cycle: An example of nutrient cycling

Question

i. As with all nutrients, carbon must be recycled (the ecosystem is CLOSED
in terms of nutrients)
● Carbon cycle includes both fast and slow pathways
Fast pathway:
Slow pathway:
b. How does carbon move from the fast pathway to the slow pathway?
c. Carbon Cycle: Slow Pathway
i. Where is carbon stored in the slow pathway?
d. Fossil fuels are formed when plants and animals are not completely
decomposed
i. The remnants are converted into coal, oil, natural gas, or rock (such as
limestone)
● Carbon returned to the atmosphere naturally returns to the fast
pathway very slowly.
e. Coal - The world’s most abundant fossil fuel
i. Coal - organic matter (woody plant material) that was compressed under
very high pressure to form dense, solid carbon structures
ii. Dirtiest fossil fuel: CO2 emissions and other contaminants1-15
Humans severely impacting the carbon cycle
i. Burning fossil fuels moves carbon from the ground to the air
● What impact does this have?
ii. Cutting forests and burning fields (deforestation)
● What impact does this have?
g. Today’s atmospheric carbon dioxide reservoir is th

Answer 1

Carbon Cycle: An Example of Nutrient Cycling

The carbon cycle is an essential process that involves the movement of carbon among the atmosphere, oceans, soils, and living organisms. This cycle can be divided into fast and slow pathways.

i. Carbon Cycle Pathways

• Fast Pathway: This pathway involves rapid processes such as photosynthesis, respiration, and decomposition. In this pathway, carbon is quickly exchanged between the atmosphere and living organisms. For example, plants absorb carbon dioxide (CO2) from the atmosphere during photosynthesis, and when they respire or decompose, CO2 is released back into the atmosphere.

• Slow Pathway: This pathway involves more gradual processes, such as the formation of fossil fuels and sedimentary carbon deposits. Carbon can be trapped in geological formations for millions of years, considerably lengthening its residence time in this pathway.

b. Transition from Fast to Slow Pathway

Carbon moves from the fast pathway to the slow pathway primarily through the process of burial and sedimentation. When organic matter from plants and animals is not fully decomposed, it accumulates in sediments; over long periods and under high pressure, it may eventually be transformed into fossil fuels like coal, oil, and natural gas.

c. Carbon Cycle: Slow Pathway

i. Storage of Carbon in the Slow Pathway: In the slow pathway, carbon is stored mainly in:

• Fossil fuels such as coal, oil, and natural gas.
• Carbonate rocks (like limestone) formed from the remains of marine organisms.
• Deep soil and peat deposits, which are the accumulation of organic matter in wetland regions.

d. Fossil Fuels Formation

Fossil fuels are formed when plants and animals undergo incomplete decomposition. The organic material, subjected to heat and pressure over millions of years, transforms into coal, oil, or natural gas. When carbon from these sources is returned to the atmosphere (usually through burning), it can enter the fast pathway, but this process occurs very slowly over geological timescales.

e. Coal as a Fossil Fuel

i. Coal: Coal is the most abundant fossil fuel, composed mainly of carbon from ancient, woody plant material that was compressed into dense structures under high pressure.

ii. Environmental Impact: Coal is considered the dirtiest fossil fuel due to its high carbon dioxide emissions and the release of other contaminants during combustion.

f. Human Impacts on the Carbon Cycle

i. Burning Fossil Fuels: The combustion of fossil fuels releases large amounts of carbon dioxide into the atmosphere, which increases the concentration of greenhouse gases. This enhances the greenhouse effect, leading to global warming and climate change.

ii. Deforestation: Cutting down forests and burning fields (deforestation) reduces the number of trees available to absorb CO2 through photosynthesis. This not only releases stored carbon from trees into the atmosphere but also limits the earth's capability to sequester carbon in the future.

g. Today's Atmospheric Carbon Dioxide Reservoir

As of now, today's atmospheric carbon dioxide reservoir is significantly higher than pre-industrial levels, primarily due to human activities like burning fossil fuels and deforestation. This rise in CO2 levels is a major contributor to climate change and its associated impacts on weather patterns, sea levels, and ecosystems worldwide.

In summary, the carbon cycle is a complex interplay of processes that are currently being significantly altered by human activities, leading to a range of environmental consequences.