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Download Friday, November 6th Cycles Review The Nitrogen Cycle The
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Friday, November 6th Cycles Review 1. What process pulls carbon out of the atmosphere? Learning Goal • Compare and contrast how carbon, phosphorus, nitrogen, and water cycle through the environment 2. What processes put carbon into the atmosphere? 3. Fossil fuels are formed during what process? 4. Which cycle does not have an atmospheric phase? 5. What will happen to the carbon atoms you ate at lunch? Agenda 6. What is transpiration? • Notes 7. What is condensation? Homework • Cycles quiz Tuesday! 8. What is evaporation? 9. How does phosphorus get into the environment naturally? The Nitrogen Cycle The Nitrogen Cycle • Nitrogen comprises 78% of our atmosphere, and is contained in proteins, DNA and RNA • Nitrification: bacteria that convert ammonium ions then into nitrate ions – Nitrogen gas is inert and cannot be used by organisms • Nitrogen fixation: Nitrogen gas converted to ammonium by nitrogen-fixing bacteria or lightning – Which can be used by some plants – Plants can take up these ions • Assimilation: uptake of nitrogen by plants and animals – Plants obtain nitrogen from the soil – Animals obtain nitrogen by eating plants or other animals • Denitrifying bacteria: convert nitrates in soil or water to gaseous nitrogen, releasing it back into the atmosphere 1 Nitrogen fixation How are humans impacting the nitrogen cycle? Atmospheric N2 Denitrification Assimilation • Synthetic production of fertilizers by combining nitrogen and hydrogen to make ammonia – Dramatically changes the nitrogen cycle – Humans are fixing as much nitrogen as nature does Nitrogen fixation • Increased emissions of nitrogen-containing greenhouse gases Mutualism • Contributes to Acid deposition Nitrogen-fixing bacteria Denitrifying Bacteria – Acidify water and soils 2
