Biogeochemical CyclesFriedland: Chapter 3 (pgs. 65-73)Botkin: Chapter 6 (pgs. 111-123)

I. Life and Chemical Elements

A. All living things are made of chemical elements and require:

1. Micronutrients2. Macronutrients

a. 24 elements required by all organismsb. Include the “Big Six”, which are the

building blocks of life • carbon• oxygen• hydrogen• nitrogen• phosphorus• sulfur

B. For life to persist elements must be available

at the right time, in the right amount, and in

right concentrations relative to one another

1. Too much of some elements can be toxic

2. Too little of some elements can limit

growth and development – limiting

factors

1. These elements are continuously recycled

throughout the atmosphere, biosphere,

hydrosphere, and lithosphere, through the

biogeochemical cycles

II. Geologic CyclesTectonic CycleA.Creation and destruction of Earth’s outer layer (the lithosphere)

1. About 100 km thick2. Broken into plates that float on denser material

and move about 2-15 cm/year

B.Plate tectonics has large scale effects1. Location and size of continents2. Alterations in climate (atmospheric and oceanic

currents)3. Ecological islands (speciation and evolution)4. Areas of volcanic activity and earthquakes

C. Plate boundaries1. Divergenta. Occurs at a spreading ocean ridge, where plates

moving away from one another b. New lithosphere producedc. Known as sea floor spreading, produces ocean

basins

2. Convergenta. Occurs when plates collideb. When heavier ocean plates meet lighter

continental plates a subduction zone is presentc. When two lighter continental plates collide a

continental mountain range may form

3. Transform faulta. Occurs where one plate slides past anotherb. San Andreas Fault in California

Boundary of NA and Pacific plates LA moving towards SF

Rock CycleA.Consists of numerous processes that produce rocks and soilsB.Depends on the tectonic cycle for energy and the hydrologic cycle for waterC.Rocks classified as

1. Igneous – made from magma that cools at or near the surface (lave from volcanoes)

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

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

D. Weathering 1. Physical weathering is the mechanical

breakdown (freeze, thaw) of rocks that produces sediment such as gravel, sand and silt

2. Chemical weathering occurs when weak acids in water dissolve chemicals from rocks

E. Erosion1. Physical removal of rock fragments from a

landscape or ecosystem2. Wind, water, ice transport and living

organisms can erode materials

Rock Cycle Diagram (Botkin pg. 116)

A. Transfer of water between the ocean, atmosphere and land

B. Driven by solar energy1. Evaporation of water from oceans and

land2. Precipitation of water on land3. Transpiration of water by plants4. Runoff from streams, rivers and

subsurface

III. The Hydrologic Cycle

Hydrological Cycle Processes (p.67)

C. Total water on earth = 1.3 billion km3

1. 97% in oceans2. 2% in glaciers and ice caps3. 0.001% in atmosphere4. The rest in fresh water on land

D. At the regional and local level, the fundamental unit of the landscape is the drainage basin (watershed)

1. The land area that contributes surface runoff to a particular stream or river

2. Used to evaluate hydrology3. Vary greatly in size4. Usually named for main stream or river (e.g.

Mississippi River)

A. Carbon is the basic building block of life and the element that anchors all organic substances

B. It is stored and transferred through the following processes:1. Photosynthesis

a. Producers take in CO2 and incorporate it into their tissues

2. Respirationa. All organisms release CO2 when they respire

b. Decomposers return CO2 to the atmosphere when they break down dead organic material

In what other form do organisms release carbon into the atmosphere?

IV.The Carbon Cycle

3. Exchangea. Large amounts of CO2 are exchanged between

ocean and atmospherei. Some dissolved CO2 enters the food web via

algaeii. Some CO2 combines with calcium ions in the

water to form CaCO3 (organism shells and sediment)

4. Sedimentation and Buriala. CaCO3 can precipitate out of water and form

limestone and dolomite rock via sedimentationb. Buried organic matter becomes fossilized over

millions of years and can be transformed into fossil fuels

5. Extractiona. Humans remove C (in the form of fossil fuels) from

the earth

6. Combustiona. Burning fossil fuels for energy and wildfires

release CO2

A. Nitrogen is essential to life Why?

B. 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

1. Performed by bacteria or abiotic processes:1.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

2.N2 can also be fixed and converted into NO-3 by lightening

and combustion, or by humans making fertilizers

V. The Nitrogen Cycle

D. NO-3 and NH4

+ can be used by producers to make proteins to build tissues, which can in turn be eaten by consumers = assimilation

E. When organisms create nitrogen-containing waste or die, decomposers feed on the organic material and create NH4

+ = ammonification

F. Nitrifying bacteria in the soil then convert NH4

+ into nitrite (NO-2), then into NO-

3 = nitrification

G. Denitrifying bacteria convert NO-3 into N2

gas that returns to the atmosphere

Nitrogen Cycle (pg. 70)

A. P is a major component of DNA, RNA and ATP

B. Phosphorous cycles between rocks, soil, ocean sediments, and living organisms

C. Does not enter the atmosphereD. Low solubility in water; much of it

precipitates out of solution forming phosphate (PO4

3-) sediment on ocean floors

E. On land, the major source of P is the weathering of rocks

VI.The Phosphorous Cycle

Phosphorus Cycle (pg. 72)

A. Sulfur is a component of proteins and allows organisms to use oxygen

B. Most S exists in rocks and is released into soil and water through weathering

C. Plants absorb sulfur through their roots in the form of sulfate (SO4

2-)

D. 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

VII.The Sulfur Cycle

A. Visually represent cycles as systems using box-and-arrow diagrams (pg. 112)

A. Flow is the amount of substance moving from one compartment to another

B. Flux is the rate of transferC. Residence time is the average time the

substance is stored in a compartmentD. The donating compartment is the source, the

receiving compartment is the sink

VIII. Cycle Diagrams

You and your lab partner are to answer the following:1.How/why is each cycle important to organisms?2.Discuss specific human actions that affect/influence each cycle (except geologic) and the consequences of those actions3.Identify which cycles have limiting factors. How do they affect the cycle and ecosystems?

Group Project(all cycles except Rock and

Tectonic)