BIOGEOCHEMICAL CYCLES

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BIOGEOCHEMICAL CYCLES

• Ecology UNIT

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What is a Biogeochemical cycle?

• ORGANISMS
• matter matter
• ENVIRONMENT

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FOUR MAJOR CYCLES

• CARBON
• NITROGEN
• PHOSPHORUS
• WATER

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Importance to Organisms

• Carbon
• Nitrogen

• Organic compounds
• Proteins nucleic acids

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• Phosphorus
• Water

• A T P ,
• Nucleic acids
• Water !!

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The Carbon Cycle

• In nature
• CO2 gas in atmosphere
• CO32- dissolved in oceans
• HCO3- dissolved in oceans
• limestone rocks
• fossil fuels (coal, oil, CH4)
• cellulose

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• In organisms
• plants/algae/cyanobacteria
• Photosynthesis (C-fixing)
• animals
• consumption of plants and/or primary consumers

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• Return to Environment
• cellular respiration
• combustion of fossil fuels
• decomposition of organic
• material

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The Nitrogen Cycle

• In nature
• N2 gas in atmosphere
• NH4 in soil
• NH3 and N-containing waste
• nitrite (NO2-), nitrate (NO3-)

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• In organisms
• plants
• absorption of NH4 or nitrate in soil
• animals
• consumption of plants and/or primary consumers

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How do plants absorb Nitrogen?

• Nitrogen Fixation
• Nitrification
• Assimilation

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Nitrogen Fixation

• Bacteria in soil and plant nodules
• N2 gas
• nitrogenase
• or lightning
• or UV radiation
• N H

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Nitrification

• Ammonium
• Ammonia
• Nitrite
• soil bacteria
• Nitrate

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Assimilation

• Plant roots absorb nitrate or ammonia formed by
  previous processes.
• Nitrogen is incorporated into plant proteins /
  nucleic acids.

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• Return to Environment
• Bacterial action
• NO3- N2 to atmosphere
• Organic cmpds NH4
• (decomposition / ammonification)

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• Animal Action
• Excretion of NH4 / NH3 in urea or uric acid.

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The Phosphorus Cycle

• In nature
• no gaseous state . Non atmospheric
• stored in rocks
• Erosion P in soil
• P in water

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• In organisms
• plants
• root absorption from soil
• animals
• consumption of plants and/or primary consumers

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• Return to the Environment
• Decomposers
• Excretion of P by animals

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The Phosphorus Cycle
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The Water Cycle

• In nature
• oceans
• air (vapor)
• groundwater
• glaciers

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• In organisms
• plants
• absorption from soil
• animals
• drinking
• eating plants / other animals

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• Return to Environment
• Transpiration in plants
• Animal / Plant Decomposition

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What distinguishes the Water Cycle from the
others??