1. Nitrogen, Carbon-Oxygen, Phosphorus, Sulfur
Ecological Cycles
Nitrogen, Carbon-Oxygen, Phosphorus, Sulfur

2. The Nitrogen cycle

3. The Nitrogen Cycle
Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins, and nucleic acids.
78% of the world’s atmosphere is nitrogen
Despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: ammonium ion (NH4+ ) and the ion nitrate (NO3- ) and CONNOT use raw atmospheric nitrogen

4. Four processes participate in the cycling of nitrogen through the biosphere:
nitrogen fixation
atmospheric fixation by lightning
biological fixation by certain microbes
industrial fixation – making ammonia
decay (ammonification) – bacteria convert dead matter and wastes into ammonia
nitrification – bacteria convert ammonia into nitrates and nitrites
denitrification – bacteria return nitrogen to the atmosphere

5. Human Influence on Nitrogen Cycle
artificial nitrogen fertilization
planting of nitrogen fixing crops
N2O has risen in the atmosphere as a result of agricultural fertilization, biomass burning, cattle and feedlots, and other industrial sources (N2O also destroys ozone)
eutrophication

7. Water Cycle

8. Water Cycle – Man’s Influence
Tropical Rain Forest – deforestation
Less trees = less tramsiration = less water in atmosphere = less rain
Olalla Reservoir
Huge groundwater store in central U.S.
Being depleted faster than replenished

9. Carbon Cycle

10. Carbon Cycle O.03 carbon dioxide in atmosphere
Plants take in CO2 and release O2 in PHOTOSYNTHEIS
Animals take in O2 and release CO2 in CELLULAR RESPIRATION
Decay also release CO2 into the atmosphere

11. Man’s Influence on Carbon Cycle
Burning fossil fuels releases CO2 into atmosphere
Cellulose in dead plant material is hard to breakdown (too big)
Accumulates undecomposed over time forming peat
Peat over time and under pressure forms fossil fuels
When fossil fuels are burned – releases carbon

12. Sulfur Cycle Sulfur Most sulfur is in rock and mineral slats
Component of proteins
Component of vitamins
Most sulfur is in rock and mineral slats
Released naturally into atmosphere from volcanoes and decomposition in wetlands
In atmosphere, SO2 reacts with water to produce sulfuric acid

14. Man’s Influence We release excess SO2 into the atmosphere by:
Burning fossil fuels
Refining petroleum products
Mining processes

15. Chemosynthesis Ocean vents in trenches
Bacteria use hydrogen sulfide H2S as energy source

16. Phosphorus Cycle Phosphorus important in DNA molecules ATP
Cell membranes
Bones
Teeth
shells

17. Slow cycle
Not much in atmosphere – but in soil, rock, and water
Big water component

18. Phosphorus Cycle