enve3503 – environmental engineering population growth the sorcerer’s apprentice
Post on 20-Dec-2015
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ENVE3503 – Environmental EngineeringPopulation Growth
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The Sorcerer’s Apprentice
Exponential Growth
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Exponential Growth
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exponential growth model, with
X0 = 1 = 0.69 d-1
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The Death Term
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another intrinsic characteristic of the organism.
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Limits to Exponential Growth(non-renewable and renewable resources)
http://wildgoosechasing.blogspot.com/2007/12/experts-world-population-will-explode.html
non-renewable resources
Logistic Growth (limitation by non-renewable resources)
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carrying capacity, KWhile some organisms may reach a population size that is limited by non-renewable resources, higher organisms would be expect to encounter limitation by renewable resources first.
http://www.cbc.ca/gfx/images/news/photos/2008/06/27/f-un-food-distribution-584.jpg
renewable resources
Limits to Exponential Growth(non-renewable and renewable resources)
The Monod Model (limitation by renewable resources)
max ds
dX Sk X
dt K S
Substrate Concentration
Gro
wth
Rat
eHalf-saturation constant: substrate level at which the growth rate is at one-half it’s maximum.
The Monod Model (limitation by renewable resources)
max ds
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Food
Sup
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Should that population grow beyond its equilibrium size or if it were to experience an interruption in food supply, e.g. a famine, the population would decline and ultimately disappear.
A population in equilibrium with its food supply is maintained at a constant level.
The Yield Coefficient (linking substrate depletion and growth
max ds
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dS Sk X
dt Y K S
dX mgXY
dS mgS
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Biom
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Life at carrying capacity …
Carrying capacity holds populations in check through density-driven phenomena such as,
• lack of space• increased incidence of disease• increased susceptibility to predation
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Consider the differences in life at carrying capacity for non-human and human populations.
A catastrophe of Malthusian proportion …
How may humans experience “misery and vice” in a catastrophe of Malthusian proportions?
The 18th Century British economist recognized that populations grew exponentially, checked only by “misery or vice”, by which he meant . He asserted that because the “means of subsistence” increased in a linear fashion, demand would eventually outstrip supply with catastrophic results.
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Soiling the global nest …
Paul Chefurka, a Canadian photojournalist and computer scientist, has suggested that as we pile environmental insult upon environmental insult, we diminish the carrying capacity of our global ecosystem. In this sense, we are not moving toward the crisis, the crisis is moving toward us!
What is the role of the environmental engineer in restoring the Earth’s carrying capacity?
Can you think of an example where this has been accomplished?
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IPAT: the elephant in the global living room
I P A T impact affluencepopulation technology
IPAT and the environmental engineer
I P A T impact affluencepopulation technology
thetechnological
solution
IPAT and us
I P A T impact affluencepopulation technology
thesocial
solution
Farmer Bean and Her Pigs
Drawings by Bill Sproule