1. Biogeochemical Cycles
Friedland: Chapter 3 (pgs ) Botkin: Chapter 6 (pgs )

2. Life and Chemical Elements
All living things are made of chemical elements and require:
Micronutrients
Macronutrients
24 elements required by all organisms
Include the “Big Six”, which are the building blocks of life
carbon
oxygen
hydrogen
nitrogen
phosphorus
sulfur
Micro - Elements required in small amounts by all life or moderate amounts by some forms of life

4. For life to persist elements must be available at the right time, in the right amount, and in right concentrations relative to one another
Too much of some elements can be toxic
Too little of some elements can limit growth and development – limiting factors
These elements are continuously recycled throughout the atmosphere, biosphere, hydrosphere, and lithosphere, through the biogeochemical cycles

5. Geologic Cycles Tectonic Cycle
Creation and destruction of Earth’s outer layer (the lithosphere)
About 100 km thick
Broken into plates that float on denser material and move about 2-15 cm/year
Plate tectonics has large scale effects
Location and size of continents
Alterations in climate (atmospheric and oceanic currents)
Ecological islands (speciation and evolution)
Areas of volcanic activity and earthquakes
Plates move about as fast as finger nails grow

7. Plate boundaries Divergent
Occurs at a spreading ocean ridge, where plates moving away from one another
New lithosphere produced
Known as sea floor spreading, produces ocean basins

8. Convergent Occurs when plates collide
When heavier ocean plates meet lighter continental plates a subduction zone is present
When two lighter continental plates collide a continental mountain range may form

9. Transform fault Occurs where one plate slides past another
San Andreas Fault in California
Boundary of NA and Pacific plates
LA moving towards SF

10. Rock Cycle
Consists of numerous processes that produce rocks and soils
Depends on the tectonic cycle for energy and the hydrologic cycle for water
Rocks classified as
Igneous – made from magma that cools at or near the surface (lave from volcanoes)

11. Sedimentary – weathered materials that accumulate in deposition basins, such as oceans, are compacted by overlying sediment layers (lithification)

12. Metamorphic – sedimentary rock buried at depths that are altered by heat, pressure, or chemically active fluids and transformed

13. Weathering
Physical weathering is the mechanical breakdown (freeze, thaw) of rocks that produces sediment such as gravel, sand and silt
Chemical weathering occurs when weak acids in water dissolve chemicals from rocks

14. Erosion
Physical removal of rock fragments from a landscape or ecosystem
Wind, water, ice transport and living organisms can erode materials

15. Rock Cycle Diagram (Botkin pg. 116)

16. The Hydrologic Cycle
Transfer of water between the ocean, atmosphere and land
Driven by solar energy
Evaporation of water from oceans and land
Precipitation of water on land
Transpiration of water by plants
Runoff from streams, rivers and subsurface

17. Hydrological Cycle Processes (p.67)
Showing the transfer of water (thousands km3/yr). It takes 1 water molecule 4,000 years to complete one cycle.

18. Total water on earth = 1.3 billion km3
97% in oceans
2% in glaciers and ice caps
0.001% in atmosphere
The rest in fresh water on land
At the regional and local level, the fundamental unit of the landscape is the drainage basin (watershed)
The land area that contributes surface runoff to a particular stream or river
Used to evaluate hydrology
Vary greatly in size
Usually named for main stream or river (e.g. Mississippi River)
Hydrology = stream flow or runoff from slopes; important in assessing ecosystems research and conservation

19. The Carbon Cycle
Carbon is the basic building block of life and the element that anchors all organic substances
It is stored and transferred through the following processes:
Photosynthesis
Producers take in CO2 and incorporate it into their tissues
Respiration
All organisms release CO2 when they respire
Decomposers return CO2 to the atmosphere when they break down dead organic material
In what other form do organisms release carbon into the atmosphere?
CH4

20. Large amounts of CO2 are exchanged between ocean and atmosphere
Some dissolved CO2 enters the food web via algae
Some CO2 combines with calcium ions in the water to form CaCO3 (organism shells and sediment)
Sedimentation and Burial
CaCO3 can precipitate out of water and form limestone and dolomite rock via sedimentation
Buried organic matter becomes fossilized over millions of years and can be transformed into fossil fuels
3. About CO2equal exchange (released by ocean and diffuses from atmosphere into ocean)
4. The amount of C removed form the food web by burial is about equal to the amount returned to the atmosphere through weathering of limestone and volcanic eruptions

21. Extraction Combustion
Humans remove C (in the form of fossil fuels) from the earth
Combustion
Burning fossil fuels for energy and wildfires release CO2

22. The Nitrogen Cycle Nitrogen is essential to life
Why?
N2 makes up 78% of the Earth’s atmosphere
Most organisms can’t use it directly
Relatively unreactive element; must be converted to nitrate (NO3-) or ammonium (NH4+) = nitrogen fixation
Performed by bacteria or abiotic processes:
Cyanobacteria (blue-green algae) and bacteria that live on the roots of legumes (beans, peas, etc) use a specialized enzyme to break N2 bonds and add H+ ions to form NH3 (ammonia), which is converted to NO-3 in the soil
N2 can also be fixed and converted into NO-3 by lightening and combustion, or by humans making fertilizers
Humans now fix more N than nature

23. NO-3 and NH4+ can be used by producers to make proteins to build tissues, which can in turn be eaten by consumers = assimilation
When organisms create nitrogen-containing waste or die, decomposers feed on the organic material and create NH4+ = ammonification
Nitrifying bacteria in the soil then convert NH4+ into nitrite (NO-2), then into NO-3 = nitrification
Denitrifying bacteria convert NO-3 into N2 gas that returns to the atmosphere

24. Nitrogen Cycle (pg. 70)

25. The Phosphorous Cycle P is a major component of DNA, RNA and ATP
Phosphorous cycles between rocks, soil, ocean sediments, and living organisms
Does not enter the atmosphere
Low solubility in water; much of it precipitates out of solution forming phosphate (PO43-) sediment on ocean floors
On land, the major source of P is the weathering of rocks
Added to fertilizer. We mine ocean floors for P

26. Phosphorus Cycle (pg. 72)

27. The Sulfur Cycle
Sulfur is a component of proteins and allows organisms to use oxygen
Most S exists in rocks and is released into soil and water through weathering
Plants absorb sulfur through their roots in the form of sulfate (SO42-)
Volcanic eruptions release sulfur dioxide (SO2), which mixes with water in the atmosphere to form sulfuric acid (H2SO4) , then falls to the ground as precipitation

28. Cycle Diagrams
Visually represent cycles as systems using box-and-arrow diagrams (pg. 112)
Flow is the amount of substance moving from one compartment to another
Flux is the rate of transfer
Residence time is the average time the substance is stored in a compartment
The donating compartment is the source, the receiving compartment is the sink

29. Group Project (all cycles except Rock and Tectonic)
You and your lab partner are to answer the following:
How/why is each cycle important to organisms?
Discuss specific human actions that affect/influence each cycle (except geologic) and the consequences of those actions
Identify which cycles have limiting factors. How do they affect the cycle and ecosystems?