1. Recycling Materials and nutrients Energy leaves system but materials are recycled

2. Water Cycle Water evaporates from seas and land Condenses into clouds (warm over oceans, cool over land) Water precipitates over land Fills lakes, rivers, aquifers and Returns to ocean

3. Carbon Cycle Plants remove carbon dioxide from atmosphere; change to sugars Sugars pass to herbivores, carnivores, scavengers, decomposers that release carbon dioxide Most carbon in oceans as bicarbonate and sediments, and eventually sedimentary rocks and fossil fuels

4. Carbon Locations

5. Human Effects on Carbon Cycle Burning fossil fuels releases carbon dioxide into atmosphere Carbon dioxide traps solar energy as heat — called the greenhouse effect Global temperatures increasing Negative Effects: melt polar ice caps, raise sea levels, change climates, change growing seasons What humans can do to help to remove carbon dioxide from the atmosphere: Burn less fuel Plant trees; carbon stored in wood

6. Nitrogen Information Nitrogen is the most abundant element in atmosphere, but not usable for most organisms For nitrogen to be available to organisms, it must be “fixed”: changed into ammonium ions (NH 4 +) or nitrate ions (NO 2 -) --------------------------------------------------------------------------- One source of fixed nitrogen is Nitrifying bacteria, some free living, most in root nodules of some plants called legumes (peas and beans)

7. Nitrogen Cycle

8. Humans and the Nitrogen Cycle Humans adding fixed nitrogen to ecosystems –fertilizers –burning fossil fuels

9. Effects of Increased Nitrogen on Ecosystems Soils become more fertile Decreases diversity Aquatic systems –Increases algae growth and plankton –Dead algae and fecal pellets increase bacterial growth –Bacteria consume oxygen –Animals leave or die — dead zone