Topic 4.3:  Carbon Cycling

Essential Idea:  Continued availability of carbon in ecosystems depends on carbon cycling.

At SHS, Topic 4.3 is taught in the following class unit(s):
​​Nutrient Cycles (unit 26)

Statements & Objectives:

4.3.U1  Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds.

• State the role of photosynthesis in the carbon cycle.

4.3.U2  In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogen carbonate ions.

• Outline the process that converts CO2 to hydrogen carbonate ion in water, leading to a reduction of the pH in the water.

4.3.U3  Carbon dioxide diffuses from the atmosphere or water into autotrophs.

• State that in diffusion, molecules move from an area of higher concentration to an area of lower concentration. ​

4.3.U4  Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere.

• ​State that carbon dioxide is a waste product of aerobic cellular respiration.​
• State that carbon dioxide diffuses out of cells into the atmosphere or water.

4.3.U5  Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground.

• ​Outline the role of methanogenic archaea in the transformation of organic material into methane.

4.3.U6  Methane is oxidized to carbon dioxide and water in the atmosphere.

• ​State that methane is oxidized to carbon dioxide in the atmosphere.

4.3.U7  Peat forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.

• Define peat.
• Outline formation of peat.

4.3.U8  Partially decomposed organic matter from past geological eras was converted either into coal or into oil and gas that accumulate in porous rocks.​

• Outline formation of coal.
• Outline formation of oil and natural gas.

4.3.U9  Carbon dioxide is produced by combustion of biomass and fossilized organic matter.

• Define combustion.
• State the products of a combustion reaction.
• State sources of fuel for a combustion reaction. ​​

4.3.U10  Animals such as reef-building corals and Mollusca have hard parts that are composed of calcium carbonate and can become fossilized in limestone.

• State that hard shells, such as in mollusk and coral, are made of calcium carbonate.

4.3.A1  Estimation of carbon fluxes due to processes in the carbon cycle.

• List seven flux processes in the carbon cycle.
• State the unit of measure for carbon flux values.  ​

4.3.A2  Analysis of data from air monitoring stations to explain annual fluctuations.​

• Sketch a graph of the annual fluctuation in atmospheric carbon dioxide concentration.
• Explain the annual fluctuation in atmospheric carbon dioxide concentration in the northern hemisphere.

4.3.S1  Construct a diagram of the carbon cycle.​

• Draw a diagram of the terrestrial carbon cycle.
• Draw a diagram of the aquatic carbon cycle.
• Define pool and flux.

4.3.NOS  Making accurate, quantitative measurements-it is important to obtain reliable data on the concentrations of carbon dioxide and methane in the atmosphere.​

• Explain why accurate measurements of CO2 and methane in the atmosphere are important.
• Outline how data on concentration of atmospheric CO2 and methane are collected.

In the News:

• Cores From Coral Reefs Hold Secrets of the Seas’ Past and Future (2018-05-29)
• Plants outweigh all other life on Earth (2018-05-21)
• The Squid That Sink to the Ocean’s Floor When They Die (2018-01-13)
• Plant respiration could become a bigger feedback on climate than expected (2017-11-17)
• ​Diversity of large animals plays an important role in carbon cycle (2017-10-10)
• Marine snowfall at the equator (2017-10-10)
• ​Tropical forests may be carbon sources, not sinks (2017-09-28)
• ​​​​Scientists map vast peat swamps, a storehouse of carbon, in Central Africa (2017-01-11)
• ​Are methane seeps in the Arctic slowing global warming? (2017-05-08)
• Newly discovered methane consumers in lakes (2017-06-07)
• Northern forests rev up carbon cycle (2013-08-08)
• Gassy Cows Are Warming The Planet, And They're Here To Stay  (2014-04-12)
• Scientists Discover Carbon Cycle Is Out Of Whack (2014-05-22)
• Everything Returns to Carbon (2011-04-20)
• Restored Forests Breathe Life Into Efforts Against Climate Change (2014-12-23)