BIOLOGY
BIOGEOCHEMICAL CYCLES NOTES
Cycles: Water, Carbon, Nitrogen and Phosphorous: energy in biosphere is transformed into useable
materials.
Matter- anything that has mass and takes up space
Nutrient-Chemical substances used for life processes
Organisms are made of water, carbon, nitrogen and phosphorous, and exchange of matter in the
biosphere occurs through biogeochemical cycles.
The Water Cycle:
Transpiration: water to atmosphere through leaves of plants
Condensation- water to the atmosphere that gathers to form clouds
Evaporation- water to the atmosphere from bodies of water or land.
Precipitation- water to the land through rain, sleet, snow or hail. Can be solid or liquid.
Percolation- water from run-off that seeps through layers of earth to reach aquifer, purified in
the process.
The Carbon Cycle:
All living things made of carbon.
Carbon is the framework of proteins, fats and carbohydrates.
Combustion- burning of fossil fuels, or organic matter, gases go to atmosphere
Photosynthesis- uptake of CO2 by plants to make glucose
Cellular respiration- CO2 is byproduct, released to atmosphere
Diffusion- CO2 taken in by plants
Bicarbonates and carbonates- compose the sea shells on the ocean floor
Deposition-deposit of carbon based substances
Fossil fuels- due to heat, pressure, and decomposition, ancient marine life depositions used for
fuel.
The Nitrogen Cycle:
Nitrogen is found in proteins, but the greatest concentration is in the atmosphere- 78%
Plants and animals cannot use atmospheric nitrogen.
Nitrogen gas is captured by bacteria in soil, water and air, and roots of plants
Nitrogen Fixation: the conversion of atmospheric nitrogen for use by plants and animals.
1. Can be fixed during electrical storms by lightning
2. Can be fixed with use of chemical fertilizers
Nitrogen enters plantsplants make proteins plants are eaten by consumers converted to
consumer proteins
Nitrogen is a limiting factor for plant growth. Low levels of nitrogen result in no growth or slow
growth.
Nitrogen returned to soil:
1. Urination- urine has high ammonia content
2. Dentrification-soil bacteria converts ammonia (NH3) to nitrogen gas for release into
the atmosphere.
The Phosphorous Cycle:
Phosphorous is essential for growth and development of organisms.
There are actually 2 cycles:
1. Short term: Phosphorous in soilplants consumersconsumers die, and
phosporous is released into the soil
2. Long term: precipitation and sedimentation traps phosphorous in rock, weathering
and erosion cause it to be released back into the cycle. Phosphates are found in
small amounts in soil, and water.
Phosphorous is also a limiting factor for growth of the producers.