Textbook Notes

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Published on 3 Jun 2011
School
UTSC
Department
Environmental Science
Course
EESA01H3
Professor
Chapter Five: Earth Systems and Ecosystem Ecology
EARTHS ENVIRONMENTAL SYSTEMS
Cycles flows of elements, compounds, and energy from reservoir to reservoir
through the Earth system
Systems show several defining properties:
System a network of relationships among a group of parts, elements, or
components that interact with and influence one another through the
exchange of energy, matter, and/or information
oReceive inputs of energy, matter, or information, process them and
produce outputs
Open system a system that exchanges energy, matter, and information with
other systems
oSystem that receive inputs of both energy and matter and produce
outputs of both
Closed system a system that is self-contained with regard to exchanges of
matter (but not energy) with its surroundings
oSystem that receive inputs and produce outputs of energy but not
matter
oMatter cycles around system but does not enter or leave it
oNo natural system is truly closed
Feedback loop a circular process in which a systems output serves as input
to that same system
oNegative feedback loop a feedback loop in which output of one type
acts as input that moves the system in the opposite direction. The
input and output essentially neutralize each others effects, stabilizing
the system
Ex: furnace turns on when room cold, off when room hot
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oPositive feedback loop a feedback loop in which output of one type
acts as input that moves the system in the same direction. The input
and output drive the system further toward one extreme or another
Ex: spread of cancer; cells multiply out of control
Common in systems altered by human impact
Dynamic equilibrium the state reached when processes within a system
move in opposite directions at equivalent rates so that their effects balance
out
oIt is dynamic meaning constantly adjusting
Homeostasis the tendency of a system to maintain constant or stable
internal conditions
oProperties of resilience and resistance are related to homeostasis
oHomeostatic systems are often said to be in a stable or steady state
oSteady state a state of dynamic equilibrium or balance in which
there is no net change in the system
Emergent properties characteristics not evident in the components alone
othe whole is more than the sum of its parts
Understanding a complex system requires considering multiple subsystems:
Many systems link with each other
Environmental systems may be perceived in various ways:
Lithosphere the rock and sediment beneath our feet, in the planets
uppermost layers
Atmosphere composed of the air surrounding our planet
Hydrosphere encompasses all water in surface bodies, underground, and in
the atmosphere
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Document Summary

 cycles flows of elements, compounds, and energy from reservoir to reservoir through the earth system.  open system a system that exchanges energy, matter, and information with other systems: system that receive inputs of both energy and matter and produce outputs of both. The input and output essentially neutralize each other"s effects, stabilizing the system.  ex: furnace turns on when room cold, off when room hot www. notesolution. com: positive feedback loop a feedback loop in which output of one type acts as input that moves the system in the same direction. The input and output drive the system further toward one extreme or another.  ex: spread of cancer; cells multiply out of control.  common in systems altered by human impact.  dynamic equilibrium the state reached when processes within a system move in opposite directions at equivalent rates so that their effects balance out: i t is dynamic meaning constantly adjusting.