Title: Biogeochemical Cycles
1Biogeochemical Cycles
- Energy Flow through and Nutrient Cycling in
Ecosystems
2http//soils.usda.gov/sqi/SoilBiology/soil_food_we
b.htm
3Biogeochemical CyclesReservoirs Pathways
Atmosphere
Biosphere
Lithosphere
Hydrosphere
4Some Major Cycles of Matter
- Water Cycle
- Rock Cycle
- Chemical Cycles
- Carbon
- Nitrogen
- Phosphorous
- Sulfur
5Nutrient Cycles
Cycling maintains homeostasis (balance) in the
environment.
6- Water cycle-
- Evaporation, transpiration, condensation,
precipitation
7Water cycle-
8- Carbon cycle-
- Photosynthesis and respiration cycle carbon and
oxygen through the environment.
9Carbon cycle-
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11Nitrogen 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.
12Nitrogen Cycle
- Only in certain bacteria and industrial
technologies can fix nitrogen. - Nitrogen fixation-convert atmospheric nitrogen
(N2) into ammonium (NH4) which can be used to
make organic compounds like amino acids. - N2 NH4
13Nitrogen cycle Nitrogen-fixing bacteria Some
live in a symbiotic relationship with plants of
the legume family (e.g., soybeans, clover,
peanuts).
14- Nitrogen cycle
- Some nitrogen-fixing bacteria live free in the
soil. - Nitrogen-fixing cyanobacteria are essential to
maintaining the fertility of semi-aquatic
environments like rice paddies.
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16N movement in a watershed
Precipitation, NO3, NH3
Watershed View of Nitrogen Transport Use
Nitrogen Fixation
N
NO3 NH3
- NO3- ions relatively mobile-washes N out of
terrestrial environment - In pristine environment, most nitrogen moves as
DON (dissolved organic N)
17Nitrogen Cycle
Atmospheric nitrogen
Lightning
Denitrification by bacteria
Animals
Nitrogen fixing bacteria
Plants
Decomposers
Nitrification by bacteria
Nitrites
Nitrates
Ammonium
18Bio-concentration
19Bioconcentrationup the Trophic Pyramid
Energy degrades
but matter does not
Toxin (e.g. heavy metals)
20- Toxins in food chains-
- While energy decreases as it moves up the food
chain, toxins increase in potency. - This is called biological magnification
Ex DDT Bald Eagles
21Carbon Cycle
Atmosphere
Biosphere
Lithosphere
Hydrosphere
22Carbon TransferBiosphere Atmosphere
Photosynthesis (Atmosphere to Biosphere)
Carbon Dioxide Water Sunlight --gt Sugar
Oxygen
Respiration (Biosphere to Atmosphere)
Sugar Oxygen --gt Carbon Dioxide Water Energy
23Carbon Cycle
Atmosphere
Biosphere
Lithosphere
Hydrosphere
24Carbon Cycle
Human Impacts
Atmosphere
Biosphere
Net Effect Increase in Carbon in Atmosphere
Lithosphere
Hydrosphere
25Nitrogen Cycle
Atmosphere
Denitification bacteria
Biosphere
- Nitrogen fixation
- bacteria
- lightning
Absorption
Waste Decomposition
Erosion
Lithosphere
Hydrosphere
26Nitrogen Cycle
Human Impacts
Atmosphere
Biosphere
Net Effect Increase in Nitrogen in water soil
- Nitrogen fixation
- industrial (fertilizer)
- combustion
Increased Erosion
Lithosphere
Hydrosphere
27Phosphorous Cycle
Never enters the atmosphere
Atmosphere
Biosphere
Absorption
Waste Decomposition
Weathering Erosion
Lithosphere
Hydrosphere
Absorption
Sedimentation
28Phosphorous Cycle
Human Impacts
Biosphere
Net Effect Increase in phosphorous in water
algal blooms Depletion in soils
Mining, use (fertilizer, detergent, etc.)
increased runoff
Lithosphere
Hydrosphere
More Phos. for organisms
29Sulfur Cycle
Bacteria Absorption
Atmosphere
Bacteria Release
Biosphere
Volcanoes Weathering
Absorption
Precipitation
Waste Decomposition
Weathering
Evaporation
Sedimentation
Lithosphere
Hydrosphere
Absorption
Deep Sea Vents
30Sulfur Cycle
Human Impacts
Atmosphere
Biosphere
Net Effect Increase in atmosphere (health
effects) and acid rain
Precipitation Acid Rain
Burning Fossil Fuels
Lithosphere
Hydrosphere