1. Biogeochemical Cycles (Nutrient Cycles)
In terms of matter, Earth is a closed system
Nothing enters or leaves, just recycled
This is the Law of Conservation of Matter!
Matter is neither created nor destroyed, but recycled and reused
Important cycles: carbon, oxygen, nitrogen, phosphorus, water
Day 7 *

2. Carbon Cycle = process where C is cycled b/w atmosphere, land, water, & organisms (during photosynthesis & cellular respiration)
Steps:
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3. How Humans Affect the Carbon Cycle
Burn fossil fuels → releases CO2 into atmosphere
More CO2 in atmosphere causes global warming through greenhouse effect
Scientists have been able to piece together a picture of the Earth's climate dating back decades to millions of years ago by analyzing a number of surrogate, or "proxyScientists have been able to piece together a picture of the Earth's climate dating back decades to millions of years ago by analyzing a number of surrogate, or "proxy," measures of climate such as ice coresScientists have been able to piece together a picture of the Earth's climate dating back decades to millions of years ago by analyzing a number of surrogate, or "proxy," measures of climate such as ice cores, boreholes, tree rings, glacier lengths, pollen remains, and ocean sediments, and by studying changes in the Earth's orbit around the sun. *

4. How You Can Reduce Your Carbon Impact:
Use gas-efficient cars
Carpool/ use public transportation
Walk or ride bike when possible
Eat locally-grown food
Use less plastics & disposable products *

5. Oxygen Cycle = process where oxygen is cycled b/w atmosphere, ocean, & organisms
All organisms need Oxygen
1. Producers release O2 during photosynthesis
CO2 + H2O + sun → C6H12O6 + O2
2. Organisms use O2 during cellular respiration
C6H12O6 + O2 → CO2 + H2O + energy
3. O2 is stored:
Dissolved in oceans
Oxygen in the atmosphere:
O2 is 21% of lower atmosphere
Ozone (O3) in upper atmosphere protects us from UV rays
Day 7 *

6. *

7. Nitrogen Cycle = process where nitrogen (N) is cycled b/w atmosphere, bacteria, & other organisms
All organisms need N for proteins & nucleic acids (DNA)
1. N2 gas must be changed by nitrogen-fixing bacteria:
They convert N2 into nitrates (NO3)
2. Plants get NO3 from soil → animals eat plants
3. Plants & animal waste puts N back into soil in form of ammonia (NH4)
4. Other bacteria convert ammonia into nitrites (NO2) & nitrates
Day 7 *

8. Nitrogen Cycle
Day 7 *

9. How Humans Affect the Nitrogen Cycle
Have doubled amount of N on land due to use of fertilizers & burning fossil fuels
Problems of too much N:
Rivers & lakes becoming acidic
Global warming
Day 7 *

10. Hydrologic (Water) Cycle = path of H2O through environment
Most H2O is stored in oceans
Ocean H2O is turned to vapor (gas) by evaporation & winds push vapor around globe
H2O vapor turns to liquid in atmosphere = condensation
Liquid falls as precipitation (rain, snow, etc.)
Living organisms use H2O, then return it to environment through:
Breathing & sweating
Waste
Transpiration from leaves (plants) (leaves sweating)
Day 7 *

11. Water Cycle
Day 7 *

12. How Humans affect the Water Cycle:
Remove H2O faster than nature can replace it
Drain wetlands → increases flooding
Pollution *

13. Phosphorus Cycle = movement of phosphorus (P) between environment & organisms
P is important in DNA and ATP
Steps:
1.Rocks erode, putting phosphate into soil and water
2. P is taken up by plants & converted to organic molecules
3. Animals eat plants
4. Decomposing plants & animals & waste return P to environment
How humans affect P cycle:
Excess phosphate from fertilizers can cause too much algal growth in water → kills fish & other organisms
Day 7 *

14. Excess P due to fertilizers!
Phosphorus
Cycle
Excess P due to fertilizers!
Day 7 *