Transcript Cycles - ScienceGeek.net

Cycles
Water, Carbon, Nitrogen
Oxygen and Phosphorus
Water (hydrologic) Cycle
Plants absorb water from the soil
Transpiration and respiration return
water to the atmosphere
Precipitation returns water to the soil
Nonmetal oxides in the atmosphere
combine with water to form acid rain
The Carbon Cycle
• Carbon is fixed by plants
–
6 CO2 + 6 H2O  C6H12O6 + 6 O2
• Carbon is given off by consumers
–
C6H12O6 + 6 O2  6 CO2 + 6 H2O
• Organisms containing carbon form fossil
fuels
• Burning fossil fuels releases carbon
–
2 C8H18 + 25 O2  16 CO2 + 18 H2O
Carbon Cycle
Arctic Carbon Cycling
The Nitrogen Cycle
Bacteria fix nitrogen from the air
Consumers and producers incorporate
nitrogen into their tissues
Nitrogen can be fixed industrially from
the air
Production of ammonia
Decay processes return nitrogen to the air
Nitrogen from fertilizers may contaminate
water sources
Aquarium Nitrogen Cycle
The Oxygen Cycle
• Oxygen is produced by photosynthesis
–
–
6 CO2 + 6 H2O  C6H12O6 + 6 O2
The largest chemical process on earth!
• Oxygen is sequestered by respiration
– C6H12O6 + 6 O2  6 CO2 + 6 H2O
C6H12O6 + 6 O2  6 CO2 + 6 H2O
6 CO2 + 6 H2O  C6H12O6 + 6 O2
The Phosphorus Cycle
• The element phosphorus (P)is released in
the form of ionic phosphate (PO43-)
– Weathering of rock, mining, some detergents
and fertilizers
•
•
•
•
Phosphate is taken up by plants and fungi
Consumers absorb phosphate from plants
Decomposers return phosphate to soil
Phosphate leaches into water supply
– May form new phosphate containing rock