How Does Nature Recycle Nutrients?

1. How Does Nature Recycle Nutrients?

2. What is the Nitrogen Cycle? • Facts: • Nitrogen (N) is an essential constituent of protein, DNA, RNA, and chlorophyll. • Nitrogen is the most abundant gas in the atmosphere (78%), but it must be fixed or converted into a usable form.

3. How is Nitrogen Fixed? • Nitrogen Fixation Methods: • High energy fixation- a small amount of atmospheric  nitrogen is fixed by lightening. The high energy combines N and H2O resulting in ammonia (NH3) and nitrates (NO3). These forms are carried to Earth in precipitation. • Biological fixation: achieves 90% of the nitrogen fixation. Atmospheric nitrogen (N2) is split and combined with hydrogen (H) atoms to eventually form ammonia (NH3).

4. Who Performs Nitrogen Fixation? • Symbiotic bacteria (eg. Rhizobium spp.) living in association with leguminous (plants in the pea/bean family).  - free-living anaerobic bacteria                    - blue-green algae (cyanobacteria) • Ammonification: Once NH3 is in the soil it combines with H+ ions to form ammonium ion (NH4), or without it to form NO3. NH4+ and NO3 are readily absorbed by plants. • Nitrification: is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates (bacteria) • Denitrification: Bacteria reduces nitrates and nitrites back into gaseous nitrogen (N2)

5. The Nitrogen Cycle

6. What is the Carbon Cycle? • All life is based on the element carbon. • Carbon is the major chemical constituent of most organic matter, from fossil fuels to the complex molecules (DNA and RNA) that control genetic reproduction in organisms. • Yet by weight, carbon is not one of the most abundant elements within the Earth's crust. In fact, the lithosphere is only 0.032 % carbon by weight. • In comparison, oxygen and silicon respectively make up 45.2 % and 29.4 % of the Earth's surface rocks.

7. The Carbon Cycle

8. Where is Carbon Stored • Living Organisms (organic molecules) • Sedimentary Rock (limestone, dolomite) • Shells of marine organisms (calcium carbonate) • Fossil Fuels • Carbon Dioxide in our atmosphere • Organic matter in our soils

9. What is the Phosphorus Cycle? • Component of DNA, RNA, ATP, proteins and enzymes • Cycles in a sedimentary cycle        - A good example of how a mineral element becomes part of an organism. • The source of Phosphorus (P) is rock. • It is released into the cycle through erosion or mining. • It is soluble in H2O as phosphate (PO4) • It is taken up by plant roots, then travels through food chains. • It is returned to sediment

10. The Phosphorus Cycle

11. What is the Oxygen Cycle?