Biogeochemical Cycles

1. Biogeochemical Cycles

2. Water Cycle • Defined: Movement of water through the atmosphere • 75% of the earth is water • 99% of water undrinkable (salty & frozen) • Water recycles over and over

3. Water rises into the atmosphere in two ways: • Evaporation: Heat changes water from a liquid to a gas • Transpiration: Water evaporates from the leaves of plants through openings called stomata How does water rise? transpiration evaporation

4. Water in the atmosphere • Warm, moist air rises and eventually cools • Condensation: process where water vapor turns into a liquid

5. What goes up….Must come down • Precipitation: Rain, snow, sleet, or hail falls when water drops become heavy precipitation

10. Water on the Ground • Runoff: Water runs down hill into rivers, lakes, streams, oceans… • Infiltration: Water soaks into the soil and collects as groundwater • Process repeats transpiration RUNOFF evaporation INFILTRATION

11. Oxygen Cycle • Autotrophs: Release O2 into atmosphere via photosynthesis • All life: Absorbs O2 to be used during cellular respiration • Respiration: creates ATP energy for cells O2 O2

12. Phosphorus (P) Cycle • Problem: No phosphorus in atmosphere • Phosphorus needed to make ATP, DNA, lipids • Step 1: Phosphorus released by weathering of rocks P P

13. Phosphorus (P) Cycle • Step 2: Producers absorb P into their roots P P P

14. Phosphorus (P) Cycle • Step 2: Producers absorb P into their roots • Step 3: Consumers ingest P when plants eaten P P P P P

15. Step 2: Producers absorb P into their roots • Step 3: Consumers ingest P when plants eaten • Step 4: Decomposer s breakdown dead matter and release P into soil • Cycle repeats Phosphorus (P) Cycle P P P P P P

16. P Phosphorus (P) Cycle P P P • Human Contribution • Adding excess P from fertilizers • P washes into lakes, etc… • Excess P causes extreme algae growth P P

17. Carbon Cycle CO2 • Carbon needed to create organic molecules • Producers • Intake: Absorb CO2 from atmosphere during photosynthesis • Output: Release CO2 during cellular respiration CO2

18. Carbon Cycle • Consumers • Intake: Carbon moves up the food chain as one feeds on another • Output: Release CO2 during respiration CO2 C CO2 C

19. Carbon Cycle • Decomposers • Input: Feed on dead organic matter • Output: Organic molecules returned to soil during decomposition C C C

20. Carbon Cycle • Human Contribution • Output: Release CO2 into atmosphere when fossil fuels (coal, oil, natural gas) are burned CO2

21. Nitrogen Cycle N2 • N = 78% atmosphere (most unusable); N needed for DNA • Step 1: Soil Bacteria • Nitrogen fixation: convert atmospheric nitrogen into ammonia • Nitrification: ammonia converted into nitrates Nitrates Ammonia

22. Nitrogen Cycle • Step 2: Producers absorb nitrates through their roots Nitrates

23. Nitrogen Cycle • Step 2: Producers absorb nitrates through their roots • Step 3: Consumers ingest nitrates through the food chain Nitrates

24. Nitrogen Cycle • Step 2: Producers absorb nitrates through their roots • Step 3: Consumers ingest nitrates through the food chain • Step 4: Decomposers return ammonia to soil • Cycle repeats Ammonia Ammonia Ammonia

25. Nitrogen Cycle O2 O NO O • How does lightning help? • Energy breaks atmospheric nitrogen into Nitrogen oxide • Nitrogen oxide falls in rain to soil N2 N N N N2 N NO O O O2 NO NO NO N2 N N O2 O O NO O2 O O

26. Review • Name and define the 6 stages of the water cycle. • How is oxygen released into the atmosphere? • In which cellular process is oxygen removed and used from the atmosphere? • Which organic molecule is created by photosynthesis? • In which cellular process is carbon dioxide released into the atmosphere? • How are humans disrupting the carbon cycle? • How does nitrogen fixation and nitrification differ? • How do plants obtain nitrogen? • Which objects release phosphorus over time? • How are humans disrupting the phosphorus cycle?