1. Chapter 4Chapter 4
Biogeochemical CyclesBiogeochemical Cycles

2. Objectives:Objectives:
 Identify and describe the flow of nutrients inIdentify and describe the flow of nutrients in
each biogeochemical cycle.each biogeochemical cycle.
 Explain the impact that humans have on theExplain the impact that humans have on the
biogeochemical cycles.biogeochemical cycles.

3. Chapter Overview QuestionsChapter Overview Questions
 What happens to energy in an ecosystem?What happens to energy in an ecosystem?
 What happens to matter in an ecosystem?What happens to matter in an ecosystem?

4. What Sustains Life on Earth?What Sustains Life on Earth?
 Solar energy,Solar energy,
the cycling ofthe cycling of
matter, andmatter, and
gravity sustaingravity sustain
the earth’s life.the earth’s life.
Figure 3-7Figure 3-7

5. Two Secrets of Survival: Energy FlowTwo Secrets of Survival: Energy Flow
and Matter Recycleand Matter Recycle
 An ecosystemAn ecosystem
survives by asurvives by a
combination ofcombination of
energy flow andenergy flow and
matter recycling.matter recycling.
Figure 3-14Figure 3-14

6. MATTER CYCLING INMATTER CYCLING IN
ECOSYSTEMSECOSYSTEMS
 Nutrient Cycles: Global RecyclingNutrient Cycles: Global Recycling

Global Cycles recycle nutrients through theGlobal Cycles recycle nutrients through the
earth’s air, land, water, and living organisms.earth’s air, land, water, and living organisms.

Nutrients are the elements and compounds thatNutrients are the elements and compounds that
organisms need to live, grow, and reproduce.organisms need to live, grow, and reproduce.

Biogeochemical cycles move these substancesBiogeochemical cycles move these substances
through air, water, soil, rock and living organisms.through air, water, soil, rock and living organisms.

7. Objectives:Objectives:
 Identify and describe the flow of nutrients inIdentify and describe the flow of nutrients in
each biogeochemical cycle.each biogeochemical cycle.
 Explain the impact that humans have on theExplain the impact that humans have on the
biogeochemical cycles.biogeochemical cycles.

8. Water’ Unique PropertiesWater’ Unique Properties
 There are strong forces of attraction betweenThere are strong forces of attraction between
molecules of water.molecules of water.
 Water exists as a liquid over a wideWater exists as a liquid over a wide
temperature range.temperature range.
 Liquid water changes temperature slowly.Liquid water changes temperature slowly.
 It takes a large amount of energy for water toIt takes a large amount of energy for water to
evaporate.evaporate.
 Liquid water can dissolve a variety ofLiquid water can dissolve a variety of
compounds.compounds.
 Water expands when it freezes.Water expands when it freezes.

9. Fig. 3-26, p. 72
PrecipitationPrecipitation
Transpiration
Condensation
Evaporation
Ocean storage
Transpiration
from plants
Precipitation
to land
Groundwater movement (slow)
Evaporation
from land Evaporation
from ocean Precipitation
to ocean
Infiltration and
Percolation
Rain clouds
Runoff
Surface runoff
(rapid)
Surface
runoff
(rapid)

10. Effects of Human ActivitiesEffects of Human Activities
on Water Cycleon Water Cycle
 We alter the water cycle by:We alter the water cycle by:

Withdrawing large amounts of freshwater.Withdrawing large amounts of freshwater.

Clearing vegetation and eroding soils.Clearing vegetation and eroding soils.

Polluting surface and underground water.Polluting surface and underground water.

Contributing to climate change.Contributing to climate change.

11. Objectives:Objectives:
 Identify and describe the flow of nutrients inIdentify and describe the flow of nutrients in
each biogeochemical cycle.each biogeochemical cycle.
 Explain the impact that humans have on theExplain the impact that humans have on the
biogeochemical cycles.biogeochemical cycles.

12. What Sustains Life on Earth?What Sustains Life on Earth?
 Solar energy,Solar energy,
the cycling ofthe cycling of
matter, andmatter, and
gravity sustaingravity sustain
the earth’s life.the earth’s life.
Figure 3-7Figure 3-7

13. Fig. 3-27, pp. 72-7

15. Effects of Human ActivitiesEffects of Human Activities
on Carbon Cycleon Carbon Cycle
 We alter theWe alter the
carbon cycle bycarbon cycle by
adding excess COadding excess CO22
to the atmosphereto the atmosphere
through:through:

Burning fossil fuels.Burning fossil fuels.

Clearing vegetationClearing vegetation
faster than it isfaster than it is
replaced.replaced.
Figure 3-28Figure 3-28

16. Objectives:Objectives:
 Identify and describe the flow of nutrients inIdentify and describe the flow of nutrients in
each biogeochemical cycle.each biogeochemical cycle.
 Explain the impact that humans have on theExplain the impact that humans have on the
biogeochemical cycles.biogeochemical cycles.

17. What Sustains Life on Earth?
• Solar energy,
the cycling of
matter, and
gravity sustain
the earth’s life.
Figure 3-7Figure 3-7

20. Effects of Human ActivitiesEffects of Human Activities
on the Nitrogen Cycleon the Nitrogen Cycle
 We alter the nitrogen cycle by:We alter the nitrogen cycle by:

Adding gases that contribute to acid rain.Adding gases that contribute to acid rain.

Adding nitrous oxide to the atmosphere throughAdding nitrous oxide to the atmosphere through
farming practices which can warm thefarming practices which can warm the
atmosphere and deplete ozone.atmosphere and deplete ozone.

Contaminating ground water from nitrate ions inContaminating ground water from nitrate ions in
inorganic fertilizers.inorganic fertilizers.

Releasing nitrogen into the troposphere throughReleasing nitrogen into the troposphere through
deforestation.deforestation.

21. Effects of Human ActivitiesEffects of Human Activities
on the Nitrogen Cycleon the Nitrogen Cycle
 Human activitiesHuman activities
such assuch as
production ofproduction of
fertilizers now fixfertilizers now fix
more nitrogenmore nitrogen
than all naturalthan all natural
sourcessources
combined.combined.
Figure 3-30Figure 3-30

22. Objectives:Objectives:
 Identify and describe the flow of nutrients inIdentify and describe the flow of nutrients in
each biogeochemical cycle.each biogeochemical cycle.
 Explain the impact that humans have on theExplain the impact that humans have on the
biogeochemical cycles.biogeochemical cycles.

23. What Sustains Life on Earth?
• Solar energy,
the cycling of
matter, and
gravity sustain
the earth’s life.
Figure 3-7Figure 3-7

24. Fig. 3-31, p. 77
Dissolved
in Ocean
Water
Marine Sediments Rocks
uplifting over
geologic time
settling out weatheringsedimentation
Land
Food
Webs
Dissolved
in Soil Water,
Lakes, Rivers
death,
decomposition
uptake by
autotrophs
agriculture
leaching, runoff
uptake by
autotrophs
excretion
death,
decomposition
mining Fertilizer
weathering
Guano
Marine
Food
Webs

25. Effects of Human ActivitiesEffects of Human Activities
on the Phosphorous Cycleon the Phosphorous Cycle
 We remove large amounts of phosphate fromWe remove large amounts of phosphate from
the earth to make fertilizer.the earth to make fertilizer.
 We reduce phosphorous in tropical soils byWe reduce phosphorous in tropical soils by
clearing forests.clearing forests.
 We add excess phosphates to aquaticWe add excess phosphates to aquatic
systems from runoff of animal wastes andsystems from runoff of animal wastes and
fertilizers.fertilizers.

26. Objectives:Objectives:
 Identify and describe the flow of nutrients inIdentify and describe the flow of nutrients in
each biogeochemical cycle.each biogeochemical cycle.
 Explain the impact that humans have on theExplain the impact that humans have on the
biogeochemical cycles.biogeochemical cycles.

27. What Sustains Life on Earth?What Sustains Life on Earth?
 Solar energy,Solar energy,
the cycling ofthe cycling of
matter, andmatter, and
gravity sustaingravity sustain
the earth’s life.the earth’s life.
Figure 3-7Figure 3-7

28. Fig. 3-32, p. 78
Hydrogen sulfide
Sulfur
Sulfate salts
Decaying matter
Animals
Plants
Ocean
Industries
Volcano
Hydrogen sulfide
Oxygen
Dimethyl
sulfide
Ammonium
sulfate
Ammonia
Acidic fog and
precipitationSulfuric acid
WaterSulfur
trioxide
Sulfur dioxide
Metallic
sulfide
deposits

29. Effects of Human ActivitiesEffects of Human Activities
on the Sulfur Cycleon the Sulfur Cycle
 We add sulfur dioxide to the atmosphere by:We add sulfur dioxide to the atmosphere by:

Burning coal and oilBurning coal and oil

Refining sulfur containing petroleum.Refining sulfur containing petroleum.

Convert sulfur-containing metallic ores into freeConvert sulfur-containing metallic ores into free
metals such as copper, lead, and zinc releasingmetals such as copper, lead, and zinc releasing
sulfur dioxide into the environment.sulfur dioxide into the environment.

30. The Gaia Hypothesis:The Gaia Hypothesis:
Is the Earth Alive?Is the Earth Alive?
 Some have proposed that the earth’s variousSome have proposed that the earth’s various
forms of life control or at least influence itsforms of life control or at least influence its
chemical cycles and other earth-sustainingchemical cycles and other earth-sustaining
processes.processes.

The strong Gaia hypothesis: lifeThe strong Gaia hypothesis: life controlscontrols thethe
earth’s life-sustaining processes.earth’s life-sustaining processes.

The weak Gaia hypothesis: lifeThe weak Gaia hypothesis: life influencesinfluences thethe
earth’s life-sustaining processes.earth’s life-sustaining processes.

31. What do you think?What do you think?
 Does life on earth control earth’s life-Does life on earth control earth’s life-
sustaining processes or does life merelysustaining processes or does life merely
influence these life-sustaining process?influence these life-sustaining process?

FRQ Format.FRQ Format.

32. Objectives:Objectives:
 Identify and describe the flow of nutrients inIdentify and describe the flow of nutrients in
each biogeochemical cycle.each biogeochemical cycle.
 Explain the impact that humans have on theExplain the impact that humans have on the
biogeochemical cycles.biogeochemical cycles.