1. Nutrient Cycles & Thermodynamics

2. DO NOW
Draw the hydrologic cycle
Label all parts of your diagram

3. Biogeochemical Nutrient Cycles

4. Biogeochemical Nutrient Cycles
Hydrologic
Carbon-Oxygen
Nitrogen
Phosphorus
Sulfur
Rock

5. Biogeochemical Cycles
describe the flow of essential elements from the environment, through living organisms, and back into the environment

6. Hydrologic Cycle

7. The hydrologic cycle

8. Hydrologic Cycle (water cycle)
1. Reservoir – oceans, air (as water vapor), groundwater, lakes and glaciers; evaporation, wind and precipitation (rain) move water from oceans to land
2. Assimilation – plants absorb water from the ground, animals drink water or eat other organisms which are composed mostly of water
3. Release – plants transpire, animals breathe and expel liquid wastes

9. Reserviors

10. Residence Times

11. The carbon-oxygen cycle

12. Carbon-Oxygen Cycle (carbon is required for building organic compounds)
1. Reservoir – atmosphere (as CO2), fossil fuels (gas, oil, coal), durable organic materials (for example: cellulose).
2. Assimilation – plants use CO2 in photosynthesis; animals consume plants
3. Release – plants and animals release CO2 through respiration and decomposition; CO2 is released as wood and fossil fuels are burned

14. The nitrogen cycle

15. Nitrogen Cycle (Nitrogen is required for the manufacture of amino acids and nucleic acids)
1. Reservoir – atmosphere (as N2); soil (as NH4+ or ammonium, NH3 or ammonia, N02- or nitrite, N03- or nitrate

16. Nitrogen Cycle
2. Assimilation – plants absorb nitrogen as either NH4+ or as N03-, animals obtain nitrogen by eating plants and other animals. The stages in the assimilation of nitrogen are as follows:
Nitrogen Fixation: N2 to NH4+ by nitrogen-fixing bacteria (prokaryotes in the soil and root nodules), N2 to N03- by lightning and UV radiation.
Nitrification: NH4+ to N02- and N02- to N03- by various nitrifying bacteria.

17. Nitrogen Cycle
3. Release – Denitrifying bacteria convert N03- back to N2 (denitrification); detrivorous bacteria convert organic compounds back to NH4+ (ammonification); animals excrete NH4+ (or NH3) urea, or uric acid.

19. The phosphorus cycle

21. Phosphorus Cycle (Phosphorus is required for the manufacture of ATP and all nucleic acids)
1. Reservoir – erosion transfers phosphorus to water and soil; sediments and rocks that accumulate on ocean floors return to the surface as a result of uplifting by geological processes
2. Assimilation – plants absorb inorganic PO43- (phosphate) from soils; animals obtain organic phosphorus when they plants and other animals
3. Release – plants and animals release phosphorus when they decompose; animals excrete phosphorus in their waste products

22. The sulfur cycle

23. Sulfur Cycle (Sulfur is required for the manufacture of proteins)
1. Reservoir – Earth’s crust as gypsum (CaSO4) and pyrite (FeS2), oceans as sulfate anions, atmosphere as sulfur dioxide (SO2)
2. Assimilation – sulfate (SO4 2–) is reduced by plants, fungi and prokaryotes
3. Release – plants and animals release sulfur when they decompose

25. The rock cycle
Rock cycle = The heating, melting, cooling, breaking and reassembling of rocks and minerals
Rocks help determine soil chemistry, which influences ecosystems
Helps us appreciate the formation and conservation of soils, mineral resources, fossil fuels, and other natural resources 25

26. Hypoxia and the Gulf of Mexico’s Dead Zone
Observations: low oxygen levels - hypoxia
Hypothesis: caused by nutrients (fertilizers) that ran into the Gulf from rivers
Experiments: monitoring oxygen (long term), water sampling (N, NaCl. Bacteria, phytoplankton); observed life; analyzed historical data
Results: phytoplankton receiving too much phosphorus from farming & sewage treatment plants
As the phytoplankton die the decomposers use up available oxygen
Solution: reduce amount of phosphorus entering the Gulf – but How?

27. Newton’s Laws
Conservation of Mass – mass cannot be created or destroyed, but can be changed to energy

28. Newton’s Laws - First
Thermodynamics – inertia – an object in motion stays in motion unless acted upon by an outside force

29. Thermodynamics – entropy– disorder increases
Newton’s Laws - Second
Thermodynamics – entropy– disorder increases
Think of entropy as heat loss
We must add more energy to compensate for the heat loss

30. Energy passes through trophic levels
One of the most important species interactions is who eats whom
Matter and energy move through the community
Trophic levels = rank in the feeding hierarchy
Producers
Consumers
Detritivores and Decomposers 30

31. Producers: the first trophic level
Autotrophs (“self-feeders”) = organisms that capture solar energy for photosynthesis to produce sugars
Green Plants
Cyanobacteria
Algae
Chemosynthetic bacteria use the geothermal energy in hot springs or deep-sea vents to produce their food 31

32. Consumers: organisms that consume producers
Primary consumers = second trophic level
Organisms that consume producers
Herbivores consume plants
Deer, grasshoppers
Secondary consumers = third trophic level
Organisms that prey on primary consumers
Carnivores consume meat
Wolves, rodents, birds 32

33. Consumers occur at even higher trophic levels
Tertiary Consumers = fourth trophic level
Predators at the highest trophic level
Consume secondary consumers
Are also carnivores
Hawks, owls
Omnivores = consumers that eat both plants and animals

34. Detritivores and decomposers
Organisms that consume nonliving organic matter
Enrich soils and/or recycle nutrients found in dead organisms
Detritivores = scavenge waste products or dead bodies
Millipedes
Decomposers = break down leaf litter and other non-living material
Fungi, bacteria
Enhance topsoil and recycle nutrients 34

35. Energy, biomass, and numbers decrease
Most energy organisms use is lost as waste heat through respiration
Less and less energy is available in each successive trophic level
Each level contains only 10% of the energy of the trophic level below it
There are far fewer organisms at the highest trophic levels, with less energy available
A human vegetarian’s ecological footprint is smaller than a meat-eater’s footprint 35

36. Pyramids of energy, biomass, and numbers

37. Food webs show relationships and energy flow
Food chain = the relationship of how energy is transferred up the trophic levels
Food web = a visual map of feeding relationships and energy flow
Includes many different organisms at all the various levels
Greatly simplified; leaves out the majority of species 37

38. Some organisms play big roles
Keystone Species = has a strong or wide-reaching impact far out of proportion to its abundance
Removal of a keystone species has substantial ripple effects
Alters the food chain

39. Species can change communities
Trophic Cascade = predators at high trophic levels can indirectly affect populations of organisms at low trophic levels by keeping species at intermediate trophic levels in check
Extermination of wolves led to increased deer populations, which led to overgrazed vegetation and changed forest structure
Ecosystem engineers = physically modify the environment
Beaver dams, prairie dogs, fungi, insects, phytoplankton