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CHAPTER 4: Introduction to Systems Theory

(d). Environmental Systems as Energy Systems

In the previous section we define an environmental system as a system where life interacts with the various abiotic components found in the atmosphere, hydrosphere, and lithosphere. Environmental systems also involve the capture, movement, storage, and use of energy. Thus, environmental systems are also energy systems.

In environmental systems, energy moves from the abiotic environment to life through processes like plant photosynthesis. Photosynthesis packages this energy into simple organic compounds like glucose and starch. Both of these organic molecules can be stored for future use. The following chemical formula describes how plants capture the Sun's light energy and convert it into chemical energy:

6CO2 + 6H2O + light energy = C6H12O6 + 6O2

The energy of light is used by plants in this reaction to chemically change carbon dioxide (CO2 ) and water (H2O) into oxygen (O2 ) and the energy rich organic molecule glucose (C6H12O6 ).

The chemical energy of photosynthesis can be passed on to other living or biotic components of an environmental system through biomass consumption or decomposition by consumer organisms. When needed for metabolic processes, the fixed organic energy stored in an organism can be released to do work via respiration or fermentation.

Energy also fuels a number of environmental processes that are essentially abiotic. For example, the movement of air by wind, the weathering of rock into soil, the formation of precipitation, and the creation of mountains by tectonic forces. The first three processes derive their energy directly or indirectly from the Sun's radiation that is received at the Earth's surface. Mountain building is fueled by the heat energy that exists within the Earth's interior.

Finally, the movement of energy in environmental systems always obeys specific thermodynamic laws that cannot be broken. We will learn more about these laws later in this textbook.


Study Guide


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Citation: Pidwirny, M. (2006). "Environmental Systems as Energy Systems". Fundamentals of Physical Geography, 2nd Edition. Date Viewed.


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05/07/2009 9:59