08 - Lecture 8 Biomes Finish biogeochemical cycles...

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9/10/10 1 Lecture 8 — Biomes • Finish biogeochemical cycles • Introduction to biomes • Biomes Hydrological Cycle • Human actions have had little direct effect on hydrologic cycle – Probably reduced plant water use through CO 2 increase – Increased water vapor in atmosphere through warming Hydrologic Cycle Carbon Cycle • Carbon serves a dual purpose for organisms: – Structural component of organic molecules – Chemical bonds provide metabolic energy Carbon Cycle • Carbon cycle in “balance” for long period before Industrial Revolution – Carbon release to atmosphere through natural processes (respiration) balanced by uptake by natural processes (photosynth.) • Now atmospheric CO 2 _ 40% _ higher than pre-Industrial – _ Fossil fuel burning __ disrupt “balance” Carbon Cycle
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9/10/10 2 Nitrogen Cycle • Nitrogen makes up about 78% of the air, but plants cannot use N 2 , the stable diatomic molecule in air – Plants acquire nitrogen through nitrogen cycle • Nitrogen-fixing bacteria Nitrogen Cycle • _ More _ “reactive” nitrogen now made by humans than by natural processes – Natural processes • _ Nitrogen-fixing bacteria _ • _ Lighting _________ – Human processes • _ Haber-bosch process _ • _ Growing leguminous(crops) __ Nitrogen Cycle Phosphorus Cycle • Normally _ less mobile _ than C, N • Abundant phosphorus stimulates plant and algal productivity – Major component of _
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This note was uploaded on 04/06/2011 for the course FNR 103 taught by Professor Staff during the Fall '08 term at Purdue.

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08 - Lecture 8 Biomes Finish biogeochemical cycles...

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