Biogeochemical cycles describe the recycling of essential chemical elements on Earth between living organisms and their surrounding environment. Key cycles include: The water cycle involving evaporation, condensation, precipitation and runoff. The carbon cycle in which carbon is exchanged between the atmosphere, organisms, oceans, fossil fuels and rocks in its various forms including carbon dioxide and methane. The nitrogen cycle which converts nitrogen between its gaseous form in the atmosphere and bioavailable forms utilized by plants and animals through processes like nitrogen fixation and denitrification.

1. Biogeochemical Cycles
• Bio means…
– life
• Geo means…
– Of earth: parts of earth are
• Land, air, water
• Chemical means…
– Molecules and/or compounds
• Cycle means…
– Repeatedly
Plants obtain nitrogen
• Cycling of materials between the environment and from nitrogen-fixing
organisms bacteria and pass it to
other organisms through
• Chemical and biological processes the food chain
• Examples
– Water cycle
– Nitrogen cycle
– Phosphorus cycle
– Carbon cycle

2. Cycles of Matter
• No definite beginning or end like food chain
(remember, energy flow is
unidirectional)…matter is recycled
• Does not use up matter…transforms it
• Biogeochemical process
– Pass same molecule/compound/element through
biosphere over and over
• Organism to organism
• First Part of biosphere (air, land, water)
• Second Part of biosphere (air, land, water)

3. Biogeomchemical cycles
• Carbon-oxygen
• Phosphorus
• Water
• Nitrogen

4. Water Cycle

6. Water cycle-

7. • Water Cycle
• Evaporation: water (in oceans, rivers, lakes) turns to water vapor and
rises
• Transpiration: water evaporates through the stomata of a plant’s leaves
and becomes water vapor
– Adhesion and cohesion enable water molecules to move from roots to
leaves
– Stomata: tiny openings in the leaves of plants
• Condensation: water vapor cools down and condenses in atmosphere to
make CLOUDS
• Precipitation: water returns to surface as rain, snow, ice
• Run-off: water that moves from mountains and hills to rivers and stream
and then eventually to ocean
• Seepage: water that seeps into the soil and is either taken up by plant
roots or becomes part of ground water
• Ground water: Water that exists beneath the earth's surface in
underground streams and aquifers that eventually becomes part of the
ocean

8. Water Cycle Impact
• Deforestation
– Freshwater returns to atmosphere by
TRANSPIRATION from tropical forests
– Cut down tropical forest=reduce water vapor in
air=changes in precipitation patterns and effects
ecosystems
• Irrigation and household water use
– Draws water up from aquifers and rivers
– If rate at which H2O is used is FASTER than the
water cycle can replace it, rivers nad aquifers may
run dry (effects ecosystems)

9. Carbon-oxygen cycle
• Carbon is the main component of all living
things
• Carbon is found in glucose, which is the
fuel for LIFE!
• What other things do we fnd carbon in?

10. Carbon cycle
Carbon released as Carbon is taken in by
• Carbon dioxide • Plants
– Animals and humans • When light is present,
release CO2 by cellular plants use photosynthesis
respiration
to make CO2 and H2O
– Volcanic eruptions
into glucose and oxygen
– Burning of fossil fuels (oils)
• Methane (CH4)
– Grasses and animals
release
• Bicarbonate ions
– Found in rock and released
during erosion

13. Carbon Cycle

14. Carbon cycle impacts
• Atmospheric CO2 levels have steadily risen (more
industrialized)
• Burning of wood and fossil fuels release CO2 into atm
• Deforestation affects carbon cycle
– Def: clearing of forests for lumber, agriculture, etc.
– Eliminates plants that absorb excess CO2 from the air
– “Slash and burn” removes plants and adds CO2 to air
• Greenhouse effect
– When atmospheric gases trap heat close to Earth’s surface
– Makes Earth “liveable”…not a bad thing as long as it is controlled
• Global warming (theory)
– Theory that there is an overall rise in global temperatures b/c of
increase in greenhouse gasses (CO2)
– NOT proven

16. Nitrogen cycle
• Where is nitrogen found in living things?
• Proteins, nucleic acids, and more!
• Do you think nitrogen is important?

17. Nitrogen cycle-
Atmospheric nitrogen (N2) makes up nearly
78%-80% of air.
Organisms can not use it in that form.
Lightning and bacteria convert nitrogen into
usable forms.

18. Nitrogen cycle
• Nitrogen gas N2
– Nitrogen-fixation by bacteria on roots of
legumes to change it into…
• Ammonia NH4+
– Nitrification by bacteria in soil to change it
into… nitrates and nitrites
– Nitrogen-fixing cyanobacteria are essential to maintaining the fertility of semi-
aquatic environments like rice paddies.
• Nitrates NO3- and Nitrites NO4-
– Denitrification by denitrifying bacteria in soil
into…
• Nitrogen gas N

20. Nitrogen Cycle

24. Atmospheric Nitrogen Cycle
Lightning nitrogen
Denitrification by
bacteria
Animals
Nitrogen fixing
bacteria
Plants
Decomposers
Nitrification by Nitrites Nitrates
Ammonium
bacteria

25. Terms to know…
• Fixation
– When N2 gas is made into a useable form (NH4) ammonia
• Nitrification
– Conversion of ammonia (NH4) into nitrates (NO3-) and
nitrites (NO2-)
• Assimilation
– when plants take up nitrates and nitrites and incorporate
into their tissue as amino acids which become proteins
• Ammonification/Mineralization
– When plants and animals die and decomposers convert
amino acids back into ammonia (NH4) and return to soil

26. Nitrogen Cycle Impacts
• Humans move large amounts of nitrogen into air or
water
– Sewage treatments, fertilizers
• Lots of Nitrogen in water (and phosphorus) enables
algae to grow rapidly on the surface…eutrophication
– As algae dies, bacteria that consumes them use up so much
available oxygen in the water that there isn't enough for the
other marine organisms
• Lots of Nitrogen (and sulfur) in Air
– Smokestacks and car exhaust pipes release nitrogen dioxide
– NO2 reacts with oxygen to make O3 (ozone) in low levels of the
atmosphere….this is very bad for living organisms
– These nitrogen and sulfur containing compounds mix with water
in the air to make NITRIC ACID and SULFURIC ACID
– These acids evaporate, condense and come down as ACID
PRECIAPTATION (acid rain)
– Acid Rain causes damage to soils and aquatic ecosystems

27. Do NOT copy word-for-word!!! -Fertilizers used in farming
-cause run-off into nearby
water=increase in nutrient
levels=phytoplankton to grow and
reproduce rapidly=algal blooms
-This bloom of algae disrupts normal
ecosystem & increases bacteria
-bacteria uses up all the oxygen in
the water
-none left for other marine life
-causes death of many aquatic
organisms that need the oxygen
-Blooms also block sunlight penetrating the
surface
-photosynthetic marine plants can’t
get sunlight
-Blooms also produce toxins that are harmful
to higher forms of life
-Cause problems along the food chain and
affect any animal that feeds on them.

28. Phosphorus cycle
• Where do we find phosphorus?
• Part of DNA, cell membranes, ATP and
ADP, activates and inactivates enzymes
• Do you think phosphorus is important?

29. Phosphorus Cycle
• NO phosphorus in the atmosphere
– Only cycles in soil and land
• Found as Phosphorus (P) or Phosphate
(PO4-)
• Primarily found in the form of mineral
apatite
– found in rocks and phosphorus minerals

30. Four Phase of Phosphorus Cycle
(Terrestrial)
• Weathering
– Weathering away of phosphate rocks leached phosphate into
soil
• Plant Uptake
– Plants take up P from soil and incorporate into tissues and
the animals eat the plants and ASSIMILATE phosphorus
into their tissue
• Decomposer release
– Plants and animals die, decomposer break down tissue and
release phosphorus back into soil
• Animal excrements
– Contain phosphorus and return to soil

31. Four Phase of Phosphorus Cycle
(Aquatic)
• Weathering
– Weathering away of phosphate rocks and soils leach phosphate into rivers and
streams
• Aquatic plant and Phytoplankton Uptake
– Take up P in water and incorporate into tissues and the marine vertebrates and
invertebrates eat the plants/plankton and ASSIMILATE phosphorus into their
tissue
• Decomposer release
– Aquatic plants and animals die, decomposer break down organic phosphate in
tissue and release inorganic phosphate back into water
• Animal excrement
– Contain phosphorus and return to water
• Phosphate Loss
– Phosphate lost to marine sediment which is eventually converted into
phosphate containing rock by geological processes

34. Sulfur Cycle
• Sulfur import in proteins
– Amino acids cysteine and cystine
• Sulfur MAINLY found in rock and soil (coal, oil, peat) as sulfate
minerals
• Weathering exposes sulfates from rocks into the soil and
aquatic ecosystems
• Plants and animals ASSIMILATE sulfates into tissues
• Death and decomposition convert organic sulfates into
inorganic sulfates
• Animal excrements add sulfates to water or soil
• Sulfates then recycle

36. Sulfur Cycle in the Atmosphere
• Natural: During decomposition in both soil and
water, decomposers convert SULFATES into
HYDROGEN SULFIDE gas that can escape into
air, water, soil and marine sediments
• Natural: Volcanic eruptions also contribute
HYDROGEN SULFIDE gas (HS) into atmosphere
• Unnatural: Power plant emissions emit
HYDROGEN SULFIDE gas (HS)

37. Fates of Hydrogen Sulfide
• In Soil
– Chemosynthetic bacteria convert HS back into inorganic sulfates, sulfuric
acid, and/or elemental sulfur
• If IRON is present, elemental sulfur is changed into iron sulfide,
which gets into soil and sediments by geological processes
• In Water
– Photosynthetic bacteria and other bacteria convert hydrogen sulfide into
inorganic and organic sulfates
• In Atmosphere
– HS gas breaks down into sulfuric dioxide (SO2)
– SO2 combines with water and becomes sulfuric acid in the atmosphere
– Precipitates as acid rain, returning sulfur to soil and water
– Acid rain kills vegetation and erodes rocks

38. Negative Effects
• Coal burning power plants
dump enormous amounts of
SO2 and sulfur particles into
atmosphere
• Prevailing winds and storm
systems carry particles over
large distances
• Precipitate acid rain falls in
places far from source
– Acid rain=global problem

40. Pollution and the Environment
• Pollution: addition of substances to the
environment that result in a NEGATIVE effect
• Biological Magnification
– Animals take in water and nutrients and sometimes
pollutants w/them
– While energy decreases as it moves up the food chain,
toxins increase in potency.
– PCBs
• Disposed in industrial wastes and Soluble in lipids of
animals
• Concentration of PCBs increases in organisms tissues
dichlor-diphenyl- increase as you move up trophic levels
trichlorethylene – DDTs
C14H9Cl5 • Chemical used to control mosquitoes and crop pests
• Soluble in fatty tissue
• Birds had high levels of DDT in their tissue and in egg
shells, which causes shells to be brittle and young birds
cannot survive

42. Damage to Ozone
• Ozone: gas in atmosphere (O3)
• Ozone absorbs UV radiation from the sun (protects organisms on
earth from harmful rays)
• Chlorofluorocarbons (CFCs) is a chemical released from aerosol
cans, refrigerator units and certain manufacturing processes
– Chlorine from CFCs pull off an oxygen from a molecule of O3,
making chlorine monoxide, ClO and ozone into regular O2
– ClO binds with another ClO making chlorine peroxide (Cl2 O2)
– There’s one less molecule of O3 in the atmosphere to protect
organisms from harmful UV radiation
– Sun also breaks the chlorine peroxide (Cl2 O2) into chlorine
atoms and another O2 molecule and the cycle continues with
more carbons interacting with ozone molecules
– “Holes in the Ozone”

45. Biodiversity
• Definition: # of species in an ecosystem;
the variety of ecosystems; the variety of
individuals in a species
• Why is biodiversity important?
– Species in ecosystem are interconnected and
depend on each other
– If one species disappears, many others
affected
– Humans depend on biodiversity as well (food,
shelter, clothing, medicine)

46. Threats to Biodiversity
• Habitat destruction
• Introduced Species
• Over Exploitation of resources

47. Conservation Biology
• Def: application of biology to counteract the threats to biodiversity
– Focus on hot spots
• Small geographic areas with high conc. of species
• Cover less than 1.5% of earth’s surface
• Hotspots of extinction
• Contain 1/3 of all plants and vertebrates
– Understand Organism’s habitats
• Helps maintain org. habitat or create new habitats
• Biologists can protect key habitat factors of species
– Balance demand for resources
• Save species or meet economic and social needs of people
• Save a forest to protect and owl but put many loggers out of work?
– Planning for a Sustainable future
• Ways nations protect environment for future:
• Zoned reserves-areas of land that are relatively undisturbed by humans
– Encourage long term ecosystem conservations
• Buffer zones-areas that surround “zoned” reserve; these buffers are minimally
impacted by people...no major envir. disturbances
– Ex. Costa Rica- 8 zoned reserves
• Sustainable development- developing natural resources so that the can renew
themselves and be available to the future…
– Ex. Forest corridor between farmlands

48. Carbon Cycle

49. Nitrogen Cycle

52. Biogeochemical activity
• Each member in group needs to have their own
paper
• Fold paper in 4
• Title each box (carbon cycle, water cycle,
phosphorus cycle, nitrogen cycle)
• Diagram each of the cycles in a box, make sure
each arrow is labeled and each animal/plant is
labeled
• On the back of each square, name the different
forms the matter takes, key players (bacteria,
plants, animals, activities)
• Processes that change/transform the matter