Re: What does Dynamic Equilibrium mean?

Question: What does Dynamic Equilibrium mean, for earth science?

Much of earth science is the quest to understand the flow of materials and energy between 
components of the earth system. Examples are numerous: water in and out of a lake or 
pond, energy in (from the sun) and out (to deep space), and specific elements such as 
carbon in the atmosphere (mostly in the form of carbon dioxide). I will use this last example 
to discuss dynamic equilibrium, but you should know that the concept is important in many 
parts of the earth system.

Carbon dioxide is always flowing to and from the atmosphere through carbon pools in the 
oceans and the terrestrial biota (plants, soils, you and me, etc.). Over relatively short 
timescales (and in the absence of human modification), this system is in dynamic 
equilibrium because the quantity of carbon dioxide in the atmosphere is constant, but at the 
same time carbon is always coming and going. This quality is what defines dynamic 
equilibrium, it is when there is measurable flow of material but the POOLS (e.g. the carbon 
dioxide concentration in the atmosphere) are stable. Carbon is flowing in and out of the 
atmosphere at almost the same rates (averaged throughout the year) so carbon in the 
atmosphere is considered to be in dynamic equilibrium.

Humans have disrupted this dynamic equilibrium by adding in additional carbon to the 
atmospheric pool in the form of fossil fuels. Previously the rates of carbon input to the 
atmosphere equaled the rates of removal of carbon (mostly by plants and into solution in 
the oceans), as defined by dynamic equilibrium. But now, inputs exceed removal rates, and 
the system is no longer in equilibrium. Carbon dioxide in the atmosphere is steadily 
increasing.

The study of dynamic equilibrium is important for earth science because its understanding 
might allow us to control the impact humans have on Earth.

A quick google search came up with the following web sites. Each will help you understand a 
component of dynamic equilibrium and its application to earth science.
 http://www.webref.org/chemistry/d/dynamic_equilibrium.htm
 http://dbhs.wvusd.k12.ca.us/Equilibrium/Dynamic-Equilibrium.html
 http://www.doc.mmu.ac.uk/aric/gccsg/6-4-1.html


Cheers,

Andrew