Bio 107 General Ecology Objectives:
Identify and describe the flow of nutrients in each biogeochemical cycle.
Explain the impact that humans have on the biogeochemical cycles.

1. BIOGEOCHEMICALBIOGEOCHEMICAL
CYCLESCYCLES
General Ecology Lecture 3bGeneral Ecology Lecture 3b
Instructor: ANGELI VALERA- MAG-ASO

2. Objectives::
Identify and describeIdentify and describe
the flow of nutrients inthe flow of nutrients in
each biogeochemicaleach biogeochemical
cycle.cycle.cycle.cycle.
Explain the impactExplain the impact
that humans have onthat humans have on
the biogeochemicalthe biogeochemical
cycles.cycles.

3. What Sustains Life on Earth?What Sustains Life on Earth?
SolarSolar
energy, theenergy, theenergy, theenergy, the
cycling ofcycling of
matter, andmatter, and
gravity sustaingravity sustain
the earth’s life.the earth’s life.
Figure 3Figure 3--77

4. Two Secrets of Survival: EnergyTwo Secrets of Survival: Energy
Flow and Matter RecycleFlow and Matter Recycle
An ecosystem survives by aAn ecosystem survives by a
combination of energy flow andcombination of energy flow and
matter recycling.matter recycling.matter recycling.matter recycling.

5. Sources and sinks:
domination of storage or
release process of a
specific material within a
reservoir
FLUX: exchange
between twobetween two
reservoirs
CYCLE: system of
connected reservoirs
that transfer and
conserve a specific
material

6. D. T. Krohne, General Ecology

7. Fig .Idealized
diagram of the
geologic
cycle, which
includes the
tectonic, hydrologic
, rock and
biogeochemical
cycles.
© 2003 John Wiley and Sons Publishers

8. PrecipitationPrecipitation
Transpiration
Condensation
EvaporationTranspiration from
plants
Precipitation
to land
Evaporation
from land Evaporation
from ocean Precipitation
to ocean
Rain clouds
Runoff
Surface runoff
(rapid)
WATER CYCLE
Ocean storage
Groundwater movement (slow)
to ocean
Infiltration and
Percolation
Surface
runoff
(rapid)

9. 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 wide temperatureWater exists as a liquid over a wide temperature
range.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 of compoundsLiquid water can dissolve a variety of compounds..
Water is the medium by which elements and otherWater is the medium by which elements and other
materials move through the ecosystemmaterials move through the ecosystem
Water expands when it freezes.Water expands when it freezes.

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.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. 15%/year
CO2 & CH4
Modified from D. T. Krohne, General Ecology

14. THE CARBON CYCLE
© 2003 John Wiley and Sons Publishers

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 atmosphereto 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 3Figure 3--2828

16. Fig 4.17 Global flux of carbon, 1850-1990.
© 2003 John Wiley and Sons Publishers

17. Idealized diagram illustrating photosynthesis
for a green plant (tree) and generalized
reaction.
© 2003 John Wiley and Sons Publishers

18. OXYGEN CYCLE
Major sources:Major sources: photodissociationphotodissociation of waterof water
vapor and photosynthesisvapor and photosynthesis
Comines with a wide range of substancesComines with a wide range of substancesComines with a wide range of substancesComines with a wide range of substances
OzoneOzone –– produced by photochemicalproduced by photochemical
reactions in thereactions in the atmophereatmophere; essential to; essential to
reduce influx of UV radiation to Earthreduce influx of UV radiation to Earth

19. FORMS OF NITROGEN

20. 50% fertilizer
(Bacteria)
Modified from D. T. Krohne, General Ecology

21. NITROGEN CYCLE

22. NITROGEN CYCLE
© 2003 John Wiley and Sons Publishers

23. Nitrogen fixers:Nitrogen fixers:
CyanobacteriaCyanobacteria
FreeFree--living soil bacterialiving soil bacteria
Bacteria associatedBacteria associated
with roots ofwith roots of
leguminous plantsleguminous plants
ActinomycetesActinomycetes
fungi, associated withfungi, associated with
roots of alders androots of alders and
other species of woodyother species of woody
plantsplants

25. 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 throughAdding 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.

26. 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 3Figure 3--3030

27. Critical Thinking IssueCritical Thinking Issue –– How are HumanHow are Human
Activities Affecting the Nitrogen Cycle?Activities Affecting the Nitrogen Cycle?
Effects of increased use of
nitrogen fertilizer:
© 2003 John Wiley and Sons Publishers
• Increased nitric acid in soil:
• Leaching of magnesium and
potassium
• Increased aluminum levels
• Plant root damage
• Changes in microbe communities
• Fish kills
• Eutrophication of water bodies
• Nitrates in drinking water
• Global effects on plant based CO2 uptake
nitrogen fertilizer:

28. D. T. Krohne, General Ecology D. T. Krohne, General Ecology
Gaseous
phase
D. T. Krohne, General Ecology D. T. Krohne, General Ecology
Modified from D. T. Krohne, General Ecology

29. Dissolved
in Ocean
Land
Food
Dissolved
in Soil Water,
uptake by
autotrophs
agriculture
leaching, runoff
uptake by
autotrophs
excretion
mining Fertilizer
weathering
Guano
Marine
Food
PHOSPHORUS CYCLE
Dissolved
in Ocean
Water
Marine Sediments Rocks
uplifting over
geologic time
settling out weatheringsedimentation
Land
Food
Webs
in Soil Water,
Lakes, Rivers
death,
decomposition
death,
decomposition
Marine
Food
Webs

31. PHOSPHORUS CYCLE
© 2003 John Wiley and Sons Publishers

32. 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 byWe 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.

33. Animals
Plants
Industries
Volcano
Hydrogen sulfide
Oxygen
Dimethyl sulfide
Ammonium
sulfate
Ammonia
Acidic fog and
precipitationSulfuric acid
WaterSulfur
trioxide
Sulfur dioxide
SULFUR CYCLE
Hydrogen sulfide
Sulfur
Sulfate salts
Decaying matter
Ocean
Metallic
sulfide
deposits

35. 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 containingRefining sulfur containing petroleumpetroleumRefining sulfur containingRefining sulfur containing petroleumpetroleum
Convert sulfurConvert sulfur--containing metallic ores into freecontaining metallic ores into free
metals such as copper, lead, and zinc releasingmetals such as copper, lead, and zinc releasing
sulfur dioxide into thesulfur dioxide into the environmentenvironment –– produceproduce
acute toxicity and major damage to vegetationacute toxicity and major damage to vegetation
(bleaching, defoliation and reduced growth);(bleaching, defoliation and reduced growth);
significant part of acid rain; irritates respiratorysignificant part of acid rain; irritates respiratory
tracttract

37. Ecosystems and the Gaia Hypothesis

38. Ecosystem defined: a community
of organisms and it’s corresponding abiotic
environment through which matter cycles
and energy flows
• Wide variation in ecosystems• Wide variation in ecosystems
• Boarders can be well defined or vague
• Can be natural or artificial, managed or
wild
• Wide range in scale
• Common to all ecosystems: energy flow
and cycling of matter

39. Gaia Hypothesis(es)
• Life has greatly affected the planetary
environment
• This alteration has allowed life to persist
• The Earth is a “super-organism” - Life controls• The Earth is a “super-organism” - Life controls
the environment in a fashion that is equivalent to
the way an organism controls its various systems
•Has not been accepted by all ecologists and
atmospheric scientists, but helps us to
understand the behavior of ecosystems and the
interaction of biogeochemical cycling.

40. The Gaia Hypothesis:The Gaia Hypothesis:
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 earthchemical cycles and other earth--sustainingsustaining
processes.processes.processes.processes.
The strong Gaia hypothesis: lifeThe strong Gaia hypothesis: life controlscontrols thethe
earth’s lifeearth’s life--sustaining processes.sustaining processes.
The weak Gaia hypothesis: lifeThe weak Gaia hypothesis: life influencesinfluences thethe
earth’s lifeearth’s life--sustaining processes.sustaining processes.