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Please read: 2nd Law, Energy (see web links)Wed: Ricklefs Ch. 7

Fri: Cunningham et al. Ch. 6

Posted for Mon 09 February 200911th class meeting

Environmental Biology (ECOL 206)University of Arizona, spring 2009

Kevin Bonine, Ph.D.Tuan Cao, Graduate TAMary Jane Epps, Graduate TA

- Energy- Thermodynamics

Evolution & Ecology • Evidence • Energy • Ethics & Equality • Economics

Current Events Assignment Due 9am each Friday-See Syllabus for Details-See Rubric on Course Website

- Lab Outside this week. Be ready for the weather!

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EXTRA CREDIT SLOTS (through spring break)

Sarah H. (Beach Boys’ Don’t Go Near the Water)Alexander J. (Deadlock’s Seal Slayer)

George H.Brianna D.Rod B.

Chris B.

Avy L.

Stasha M.Kyle D.Brett C.

Jackie B.Emily W.

Whitney C.

4art by Holly Randallsponsored by EEB, Poetry Center, the UA Bookstore & others  at UA

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Where does the energy on earth come from?

Where does the energy for human lifestyles come from?

If we use energy does that mean it is unavailable for other species?

If we use resources, does that mean they are unavailable for other species?

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Energy

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Energy can…

1. Change position2. Change physical composition3. Change temperature

… of matter

Potential Energy (of position)

Kinetic Energy (of motion)

8Withgott&Brennan (2007)

Energy, 1st and 2nd Laws of Thermodynamics, Entropy

Energy Quality

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First law of thermodynamics:

Energy is Conserved!

But its quality changes.

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The second law of thermodynamics summarizes our experience with spontaneous happenings:

All kinds of energy spontaneously spread out from where they arelocalized to where they are more dispersed, if they're not hindered from doing so.

The opposite does not occur spontaneously -- you don't see:

- rocks concentrating energy from all the other rocks around them and jumping up in the air, while the ground where they were cools down a little

- pans in a cupboard getting red hot by taking energy from the other pans or from the air or the cupboard.

http://www.2ndlaw.com/entropy.html

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Entropy:A way to measure the energy that disperses or spreads out in a process (at a specific temperature).

Entropy change, delta S, measures how much energy is dispersed in a system, or how widely spread out the energy of a system becomes (at a given temperature).

Example: melting ice to water at 273 K (= 0C),

where delta S = q(rev)/T. In that equation, q (the enthalpy of fusion) is how much "heat" energy was spread out in the ice to change it to water. [rev=reversible]

A negative delta S (a decrease in entropy) is not spontaneous.

http://www.2ndlaw.com/entropy.html

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How are these laws of thermodynamics related to

environmental biology?

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Photosynthesis

6CO2 + 6H2O + energy C6H12O6 + 6O2solar “sugar”

14Withgott&Brennan (2007)

EnergyElectromagnetic Spectrum

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15Withgott&Brennan (2007)

Photosynthesis

- Light Rxns

- “Dark” Rxns

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Do plants use oxygen?

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Photosynthesis

Cellular Respiration

6CO2 + 6H2O + energy C6H12O6 + 6O2

C6H12O6 + 6O2 6CO2 + 6H2O + energy

2/3

solar “sugar”

“sugar”(glucose)

(ATP)

[2nd Law of Thermodynamics]

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Ectothermyvs. Endothermy

What percent of the food a mouse eats is turned into biomass?How about a toad? Why? What are the implications for ecosystems, food webs, and energy flow?

Approx. 1%Approx. 50%

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Ethanol

E85

Net Energy?

Does ethanol make sense?

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24http://www.citruscollege.edu/pic/46/0855al.jpg

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~1%

Resources

How do we power our societies?

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Most geologists view crude oil and natural gas as the product of compression and heating of ancient organic materials over geological time. According to this theory, oil is formed from the preserved remains of prehistoric zooplankton and algae which have been settled to the sea bottom in large quantities under anoxic conditions. (Terrestrial plants tend to form coal) Over geological time this organic matter, mixed with mud, is buried under heavy layers of sediment. The resulting high levels of heat and pressurecause the remains to metamorphose, first into a waxy material known as kerogen which is found in various oil shales around the world, and then with more heat into liquid and gaseous hydrocarbons in a process known as catagenesis. Because most hydrocarbons are lighter than rock or water, these sometimes migrate upward through adjacent rock layers until they become trapped beneath impermeable rocks, within porous rocks called reservoirs. Concentration of hydrocarbons in a trap forms an oil field, from which the liquid can be extracted by drilling and pumping. Geologists often refer to an "oil window" which is the temperature range that oil forms in—below the minimum temperature oil remains trapped in the form of kerogen, and above the maximum temperature the oil is converted to natural gas through the process of thermal cracking. Though this happens at different depths in different locations around the world, a 'typical' depth for the oil window might be 4–6 km. Note that even if oil is formed at extreme depths, it may betrapped at much shallower depths, even if it is not formed there. (In the case of the Athabasca Oil Sands, at the surface.) Three conditions must be present for oil reservoirs to form: first, a source rock rich in organic material buried deep enough for subterranean heat to cook it into oil; second, a porous and permeablereservoir rock for it to accumulate in; and last a cap rock (seal) that prevents it from escaping to the surface.

http://en.wikipedia.org/wiki/Petroleum

Petroleum

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Energy flows and material cycles.

28http://w2.byuh.edu/academics/domckay/Speeches/Mckay/Photo/D_Andersen2.jpg

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More efficient to go more slowlyBut need to factor in “fixed” costs

(e.g., lights, onboard computers, etc.)

http://home.hiwaay.net/%7Ebzwilson/prius/calculated_MPG_Rev_B.jpg

Energetic cost to move car