lecture 11-20 and 11-23

lecture 11-20 and 11-23 - I. II. III. IV. To S Toxins in...

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I. To II. S III. Toxins in the Environment a. Humans release immense amount of toxins into environment b. Toxins concentrate at higher trophic level -> biomagnifications (i.e. DDT pesticide) IV. Atmospheric carbon dioxide and global warming a. What is greenhouse effect? i. Solar radiation (sunlight) passes through atmosphere ii. Absorbed by earth, re-emitted as infrared radiation (heat) iii. Gasses not transparent to infrared radiation – some heat is radiated back to earth iv. Moon is same distance from sun, yet moon’s climate is extreme; no greenhouse effect v. Atmospheric greenhouse effect – greenhouse gasses block heat vi. Most important greenhouse gasses: water, carbon dioxide, methane b. Carbon dioxide (CO2), methane (CH4) -> contributors to global warming i. Carbon Dioxide 1. Svante Arrhenius – published in 1896 that CO2, from burgeoning industry, would warming climate a. Theoretical b. Predicted double CO2, increase 5 to 6 degrees C c. Swede, though warmer climate would be great 2. Charles David Keeling (SIO), measure CO2 from 1958 – 2005 ii. Methane 1. Sources: enteric fermentation (ruminants); anaerobic decomposition, high organic matter, low O2: wetlands, landfills rice cultivation, permafrost?; natural gas, coal mining, etc c. Evidence that temperature is rising i. Proxy data – info about temperature from data other than thermometers
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ii. Types of proxy data: 1. Ice cores a. Scientists drill in ice in places with permanent ice/snow like Greenland, Antarctica b. Read rings in ice, like tree rings; calibrate with events like volcanoes c. Analyze bubbles ancient air trapped d. Ratios of different isotopes indicate average temp when gas was trapped 2. Tree rings a. In seasonal climate, trees form annual growth rings around circumference
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This note was uploaded on 12/10/2008 for the course BILD 632282 taught by Professor Henter during the Fall '08 term at UCSD.

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lecture 11-20 and 11-23 - I. II. III. IV. To S Toxins in...

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