1. MATERIAL CYCLING
IN ECOSYSTEMS
Lecture 3 NS5 1st 2010-2011

2. THE CYCLING OF MATERIALS
IN THE ENVIRONMENT
• LAW OF ECOLOGY #2:
EVERYTHING MUST GO
SOMEWHERE
• LAW OF
THERMODYNAMICS:
ENERGY IS NOT
CREATED NOR
DESTROYED

3. BIOGEOCHEMICAL CYCLING
• The movement of elements and compounds that
are essential to life
• Materials are transported through organisms,
the atmosphere, water and land in a series of
CYCLES
• “Bio” – life, participation of organisms
• “Geo” - abiotic environment as source of
nutrients
• “Chemical” – nature of substances being
cycled

5. BASIC TYPES OF CYCLES
• Gaseous type – the reservoir is the
atmosphere and/or hydrosphere (e.g. N2,
CO2, O2)
• Sedimentary type – the reservoir is the
Earth’s crust (e.g. Phosphorus)
• Linkage type – the reservoir includes
major pathways in air, water, and crust (e.g.
sulfur)

6. WHEN THE PROBLEMS
COME IN
• Errors in Nutrient Cycling
• A’  A’’  A’’’’  A’
• Pollution – accumulation of a chemical form that is higher than the
standards
• Non-biodegradable substances – change to form new chemical structure
where no organism has yet to utilize it
• Reduction of the concentration of other chemical forms – limits growth of
the subsequent components of the cycle
• Eutrophication - the channeling of a substance to other pathways (greater
amounts of phosphates in aquatic systems)

7. INTRODUCING
THE CYCLES OF
NATURE
BIOGEOCHEMICAL CYCLES

8. THE HYDROLOGIC CYCLE OR
WATER CYCLE
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9. PURPOSE: Mediates Nutrient Cycle and
A Major Energy Dissipation Pathway
• IMPACTS OF HUMAN
INTRUSION
• More consumption than supply
• Pumping waters from aquifers - not a
normal part of the water cycle
• Garbage and wastes pollute the water
and clog drainage systems induces
flooding
• Asphalting – render the ground
impervious to water blocks infiltration
POLLUTION: a change in transfer rate of water and nutrients that can lead directly or
indirectly to a degradation of human health or degradation of plant and animal life

10. •
OXYGEN CYCLE
Type: Gaseous (21%)
• Major Reservoir: Atmosphere
• Forms: Free and Molecular Oxygen
• Sources: Photosynthesis from producer AND
Photodissociation of Water Vapor
• Fate of Free O2:
• Reach higher levels of trophosphere and reduced to
ozone (provides protection by filtering out the sun's UV
rays)
• May react with chemicals and organic compounds of the
earth’s crust
• May be used up in cell respiration which release CO2 to
be used by autotrophs to produce more O2

11. IMPACTS OF HUMAN
INTRUSION
• CFC’s (chlorofluorocarbons)
deplete ozone layer “ozone hole”
• Eutrophication (nutrient
enrichment from agricultural and
domestic wastes) leads to depletion
of oxygen in water
• Combustion of fossil fuels and
removal of vegetation (deforestation)
deplete the supply of oxygen in the
atmosphere

12. CARBON CYCLE
• Type: Gaseous Cycle
• Major Reservoir : Atmosphere but also calcium carbonate in shells and limestone, as
well as fossil fuels
• Significance : Major element of organic compounds; building blocks of all biomolecules
• Processes
• Photosynthesis removes CO2 while respiration and combustion add CO2 to the
atmosphere.
• CO2 from air and water combine to form bicarbonate (HCO3) – source of carbon
for aquatic producers. Carbonic acid makes rainwater also slightly acidic
• Similarly, when aquatic organisms respire, CO2 is released and combine with water to
form HCO3. HCO3 (water) = CO2 (air)

13. The global carbon cycle includes the earth's atmosphere, oceans,
vegetation, soils and fossil fuels

14. CARBON RESERVOIRS

15. CONTROVERSIAL ISSUES ASSOCIATED
WITH CARBON CYCLE

16. NITROGEN CYCLE
• Type: Gaseous Cycle
• Major reservoir – ATMOSPHERE
• Importance – Essential for many
biological processes, constitutes part
of proteins (amino acids), in bases of
nucleic acids that make up DNA and
RNA
• 79% of atmosphere is made up of
nitrogen (N2) but this is INERT
• It must be fixed for organisms to
utilize it

17. IMPACTS OF HUMAN
INTRUSION
• USE OF NITROGEN FERTILIZERS • NITROGEN OXIDES RELEASED THROUGH
COMBUSTION
• Human use of nitrogen fertilizers causes
runoff, leading to eutrophication in aquatic • Burning of fossil fuel + automobiles : source
systems (e.g. eutrophication) of nitrogen dioxide
• NITRATES LEACHING INTO • Ozone + PAN Photochemical Smog
GROUNDWATER
• LIVESTOCK RELEASE OF LARGE AMOUNTS
• Nitrogen level in drinking water rises OF AMMONIA (FROM WASTES)
• A large rise of nitrogen in drinking water • The ammonia released from wastes of
supplies leads to Methemoglobinemia / livestock can have detrimental effects on
Blue-Baby Syndrome fish and other organisms
• There is reduction in diversity

18. PHOSPHORUS CYCLE
• Type: Purely Sedimental
• Major reservoir – Earth’s crust
• Gradual cycle - It has no gaseous phase
• Phosphorous normally occurs in nature as part of phosphate ion.
• Most phosphates found as salts in ocean sediments or in rocks.
• Over time : geologic processes can bring sediments from ocean to land, and weathering
can bring it from land to ocean
• Importance
• Phosphorous constituent of nucleic acids in DNA, and energy currency of cell ATP.
• Phosphorous -also found in bones, in phospholipids which are found in biological
membranes.

19. IMPACTS OF HUMAN
INTRUSION
• Humans mine phosphate ores
for use in fertilizer production
and detergents
• Human actions could lead to
eutrophication of aquatic
systems which cause algal
blooms
• Algal blooms cause fish kills

20. SULFUR CYCLE
• Type: Sedimentary cycle with atmospheric
component
• Major reservoir – inorganic sulfur in rocks
and fossil fuel
• Biological Importance
• Sulfur is an important element in
protoplasm which is an important
component of some amino acids.
• Sulfur is part of proteins, vitamins and
hormones

21. CONTROVERSIES
ASSOCIATED WITH THE
SULFUR CYCLE
ACID RAIN

22. THE CYCLING OF
HEAVY METALS
BIOMAGNIFICATION AND
BIOREMEDIATION

23. MERCURY
• Fish can be contaminated with
methylmercury from neighboring
industrial plants
• They discharge mercury wastes into
water
• Result : Minamata disease or
Mercury Poisoning
• Effects : blindness, deafness, lack of
coordination, intellectual
deterioration

24. CADMIUM
• Itai-itai disease is cadmium poisoning,
first in Japan 1950
• Cadmium was released into the river
by mining companies in the mountains
• Causes softening of the bone, and
kidney failure
• Name of disease derived from painful
screams because of severe pain in
joints and spine of victims “pain-pain”

25. LEAD
• Lead poisoning =
Increases level of lead
leads to negative effects
on nervous and
reproductive system
• e.g. Lead containing
gasoline, Paints, Batteries,
Electric Wires, Cables etc

26. HYDROCARBON
• DDT – (dichlor-diphenyl-
trichloroethane) “organochlorine
insecticide”
• Banned in 1972
• Exposure to DDT causes eggshell
thinning in bird species eg. raptors,
eagles, peregrine falcons
• Toxic to humans and animals when
swallowed or absorbed through the
skin

27. BIOLOGICAL MAGNIFICATION
• It is the increase in concentration of an element
or compound that occurs in the food chain as a
result of food chain energetics or degradation
of substance.
• Accumulation of chemicals in higher predators
or in higher trophic levels
• Chemical concentration is said to be magnified
thousand fold in tissues of higher trophic level
organisms
• It is important in ecology because : it indicates
that solution to certain types of pollution is not
dilution because food chains will concentrate
the pollutant
ANSWER : BIOREMEDIATION

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MEETING:
POPULATION