1. Biogeochemical Cycles
Biology, Geology and Chemistry
Cycle
Nutrients through the Ecosystem

2. I. General Information A. Biogeochemical cycles =
materials cycle between the living and physical parts of an ecosystem
B. Types of cycles
1. Water
2. Carbon
3. Nitrogen

3. II. Water Cycle

4. II. Water Cycle Driven by the Sun B. Steps of Water Cycle
1. Evaporation –
a. Sun heats Earth
b. H2O evaporates
c. H2O goes into atmosphere as
H2O vapor

5. II. Water Cycle 2. Condensation H2O condenses
(goes from gas to liquid)
to form
clouds

6. II. Water Cycle 3. Precipitation H2O leaves clouds, falls on Earth
E.g. rain, snow, sleet, hail
4. Percolation / Infiltration
H2O enters soil, becomes groundwater

7. II. Water Cycle
5. Run–off
Some H2O moves on surface to rivers, lakes & oceans
6. Transpiration
H2O released from plant leaves,
returns to atmosphere

8. II. Water Cycle C. Where is the H2O on Earth? 1. Oceans 97.2%
2. Glaciers
2.15%
3. Lakes
0.009%
4. Soil
0.005%
5. Atmosphere
0.001%
6. Streams
0.0001%

9. II. Water Cycle

10. III. Carbon Cycle

11. III. Carbon Cycle How does carbon enter the living part of the cycle?
1. Photosynthesis
Plants, algae, & cyanobacteria use CO2 to make
organic compounds (sugars)
2. Nutrients move C through trophic levels
Consumers move organic compounds

12. III. Carbon Cycle
B. How does carbon get back into the physical part of the cycle?
1. Respiration
O2 used
to break down sugars,
CO2 released

13. III. Carbon Cycle 2. Combustion Fossil fuels & wood burned
CO (carbon monoxide) released to atmosphere
Factory & Auto emissions release CO to atmosphere

14. III. Carbon Cycle 3. Erosion CaCO2 from shells returned to system
as sediment
Shelled organisms die
Sediment returns C to ecosystem by erosion (wind & water)

15. III. Carbon Cycle 5. Decomposition of waste and dead materials
Some dead organisms become fossil fuels
Some dead organisms and waste decay, returning nutrients to the soil

16. III. Carbon Cycle

17. IV. Nitrogen Cycle

18. IV. Nitrogen Cycle General information 1. N needed to make proteins
Proteins = large molecules that perform almost all of living organisms’ vital f(x)s (functions)

19. IV. Nitrogen Cycle 2. N hard to convert into a form usable by plants
3. Most steps of N cycle occur in the soil
4. Bacteria very important to the N cycle

20. IV. Nitrogen Cycle B. Steps of the N cycle 1. Nitrogen fixation
Bacteria work with
legumes
(peas, beans, peanuts)
to take N2 from atmosphere,
put it into the soil

21. IV. Nitrogen Cycle 2.Ammonification Animals & plants deposit
nitrogenous waste
Decomposers
(bacteria & fungi) convert
organic N
(proteins) to ammonia (NH3)

22. IV. Nitrogen Cycle NO2- + NO3- 3. Nitrification
Another kind of bacteria convert ammonia (NH3) → to ammonium
to nitrites (NO2-) & nitrates (NO3-)
NH3 → NH4 + →
NO NO3-

23. IV. Nitrogen Cycle 4. Denitrification Another kind of bacteria
convert nitrites and nitrates
to nitrogen gas
NO NO3- → N2

24. IV. Nitrogen Cycle