1. Biogeochemical Cycles
Water and Carbon Cycles

2. Biogeochemical Cycles
What is a Biogeochemical Cycle?
Only so much matter on earth because it is acts as a closed system.
Energy enters as sunlight, but no matter usually exits or enters.
Open system: Energy AND matter are exchanged.
These cycles act as a way to recycle matter within the biosphere from one form to another.

3. Nutrient Cycles Carbon - key ingredient in living tissue
“Carbon-based” life forms
Nitrogen - required for amino acids used in protein synthesis
What are our sources of protein?
What do we use proteins for?
Phosphorus - required for DNA and RNA
Why is this important?

4. Water Cycle
Water is required by all living things on Earth, including us.
The water cycle recycles Earth’s fixed supply of water.
Cycles through atmosphere, ocean, and land.
It is different from other cycles in that water does not undergo chemical changes, only physical changes.
Powered by the sun.

6. Water Cycle Major processes that bring water into the atmosphere
Evapotranspiration
Evaporation - water heats up, forming water vapor, which then moves into atmosphere.
Transpiration - water from plant leaves evaporates.
Condensation
Cloud formation as water vapor in atmosphere cools, condensing into the small droplets that form clouds.

7. Water Cycle Major process that brings water out of the atmosphere:
Precipitation (requires condensation nuclei)
Droplets that formed clouds become too large and are released as snow, sleet, hail, or rain.

8. Water Cycle Processes on land: Runoff
Precipitation “runs” along land until it reaches a body of water, such as a lake, river, or ocean.
Seepage (aka infiltration)
Precipitation “seeps” (moves into) soil to form ground water below the soil’s surface.
Root uptake
Plants absorb ground water from soil via their roots.

9. Water Facts
390,000 cubic kilometers of water evaporates and enters atmosphere each year.
Equivalent to 185,000,000,000,000,000 bottles of 2 liter soda.
Most evaporates from and precipitates back into the oceans… Why is this?
Ocean makes up nearly 75% of Earth’s surface.
Water that precipitates on land runs back through streams and rivers.
Quadrillion is the word for the big number

10. Carbon Cycle Carbon is required to synthesize all organic material.
How is carbon taken up and released?
Photosynthesis, respiration, decomposition
Erosion, volcanic activity, and other geological activity
Fossil fuel formation (deposition)
Human activity
All these activities transfer carbon dioxide (0.038% of troposphere).

12. Carbon Facts 71% of world’s carbon is in the oceans.
Mostly as carbonate and bicarbonate (dissolved ionic forms of carbon dioxide).
22% exists as fossils.
3% contained in dead organic matter and phytoplankton.
3% held in terrestrial ecosystems.
Only 1% within the atmosphere as carbon dioxide.

13. Carbon Cycle How can carbon get into the ocean?
Respiration by ocean animals
Precipitation that contains dissolved carbon dioxide
Erosion of carbonate rocks (limestone) formed from animal skeletons and shells

15. Nature’s Thermostat CO2 is an important global climate regulator.
Too much removal from the cycle, then the atmosphere will cool.
Too much generation from the cycle, then the atmosphere will get warmer.
What could be causing this?

16. Homework
For both the Water and Carbon cycles, research three ways that humans are affecting the cycles.
Name VERY specific activities.
Describe specifically what aspects of the cycle are being changed.
Explain how the change brings about larger changes in the global ecosystem (think abiotic and biotic).
DUE TUESDAY!!!