The document discusses several biogeochemical cycles, including the carbon, nitrogen, phosphorus, and sulfur cycles. These cycles describe the movement of chemicals through the biosphere, atmosphere, hydrosphere and lithosphere. Chemicals cycle through these spheres via processes like evaporation, precipitation, erosion, and deposition. Limiting factors can impact the availability of elements like carbon, nitrogen, oxygen, hydrogen, phosphorus and sulfur that are required by living things. The tectonic, hydrologic, and rock cycles also interact to move Earth's materials.

1. Cycles and cycle models
The Biogeochemical Cycles

2. How Chemicals Cycle
• Biogeochemical Cycle
– The complete path a chemical takes through
the four major components – or reservoirs –
of Earth’s systems
1. Atmosphere
2. Hydrosphere
3. Lithosphere
4. Biosphere

3. Chemical Reactions
• Chemical reaction:
– The process in which new chemicals are
formed from elements and compounds
through chemical change

4. Biogeochemical Cycles and Life:
Limiting Factors
• Macronutrients
– Elements required in large amounts by all life
– Include the “big six” elements that form the fundamental building
blocks of life:
carbon oxygen
hydrogen phosphorus
nitrogen sulfur
• Micronutrients
– Elements required either in
• small amounts by all life or
• moderate amounts by some forms of life and not all by others
• Limiting factor
– When chemical elements are not available at the right times, in
the right amounts, and in the right concentrations relative to each
other

5. The Geologic Cycle
• The Geologic Cycle:
– The processes responsible for formation and
change of Earth’s materials
– Best described as a group of cycles:
• Tectonic
• Hydrologic
• Rock
• Biochemical

6. Tectonic Cycle
• Tectonic cycle:
– Involves creation and destruction of the solid
outer layer of Earth, the lithosphere
• Plate tectonics:
– The slow movement of these large segments
of Earth’s outermost rock shell
– Boundaries between plates are geologically
active areas

7. Tectonic Cycle: Plate
Boundaries
• Divergent plate boundary:
– Occurs at a spreading ocean ridge, where plates are
moving away from one another
– New lithosphere is produced (seafloor spreading)
• Convergent plate boundary
– Occurs when plates collide
• Produces linear coastal mountain ranges or continental
mountain ranges
• Transform fault boundary
– Occurs where one plate slides past another
• San Andreas Fault in California

8. The Hydrologic Cycle
• The Hydrologic Cycle:
– The transfer of water from the oceans to the
atmosphere to the land and back to the
oceans. Includes:
• Evaporation of water from the oceans
• Precipitation on land
• Evaporation from land
• Runoff from streams, rivers, and sub-surface
groundwater

9. The Rock Cycle
• The rock cycle:
– Numerous processes that produce rocks and
soils
– Depends on other cycles:
• tectonic cycle for energy
• Hydrologic cycle for water
– Rock is classified as
• Igneous
• Sedimentary
• Metamorphic

10. The Carbon Cycle
• Carbon is the element that anchors all
organic substances
• The carbon cycle:
– Carbon combines with and is chemically and
biologically linked with the cycles of oxygen
and hydrogen that form the major compounds
of life

11. Botkin & Keller
Environmental Science 5e

12. The Carbon-Silicate Cycle
• The carbon-silicate cycle:
– A complex biogeochemical cycle over time scales as
long as one-half billion years.
– Includes major geological processes, such as:
• Weathering
• Transport by ground and surface waters
• Erosion
• Deposition of crustal rocks
– Believed to provide important negative feedback
mechanisms that control the temperature of the
atmosphere.

13. The Nitrogen Cycle
• The nitrogen cycle:
– Cycle responsible for moving important nitrogen
components through the biosphere and other Earth
systems
– Extremely important because nitrogen is required by
all living things
• Nitrogen fixation:
– The process of converting inorganic, molecular
nitrogen in the atmosphere to ammonia or nitrate
• Denitrification:
– The process of releasing fixed nitrogen back to
molecular nitrogen

14. The Phosphorus Cycle
• The phosphorus cycle:
– Involves the movement of phosphorus
throughout the biosphere and lithosphere
– Important because phosphorus is an essential
element for life and often is a limiting nutrient
for plant growth.