Biogeochemical CyclesBiogeochemical Cycles

describe the flow of elementselements from the

environment through living things and back to the

environment.

Biogeochemical Cycles

Reservoirsplaces (called reservoirs) where the elements are accumulated or held

AssimilationTransfer of elements from the abiotic into the biotic

ReleaseTransfer of elements from the biotic back into the abiotic

Biogeochemical Cycles

Hydrological CycleHydrological Cycle(water cycle)

Reservoirs

Open water - oceans, lakes, rivers……

Water vapor -clouds, fog

Groundwater

Glaciers, snow and ice

Hydrological CycleHydrological Cycle(water cycle)

Assimilationplants

– absorb water from the ground

animals – drink water– eat other organisms which are composed mostly

of water

Hydrological CycleHydrological Cycle(water cycle)

Release plants

– Transpiration from leaves of plants

animals – Breathing releases water vapor– Expel liquid wastes– Evaporation off the surface of the body

Hydrological Cycle

Carbon CycleCarbon Cycle(carbon is required for building organic compounds)

Reservoir

The atmosphere (as CO2)

Fossil fuels (oil, coal,…)

Organic materials (tissues of plants and animals).

Carbon CycleCarbon Cycle(carbon is required for building organic compounds)

Assimilation

plants

use CO2 in photosynthesis

animals consume plants or other animals made up of carbon compounds

Carbon CycleCarbon Cycle(carbon is required for building organic compounds)

Release

plants release CO2 during breathing and decomposition

animals release CO2 during breathing and decomposition

CO2 is released during combustion of fossil fuels and other materials

Carbon Cycle

Nitrogen CycleNitrogen Cycle(Nitrogen is required for the manufacture of

amino acids and nucleic acids)

Reservoirs

In the atmosphere (as N2)

In the soil as

NH4+ or ammonium

NH3 or ammonia

N02- or nitrite

N03- or nitrate

Assimilation

plants can absorb either NH4+ or N03

-

animals obtain nitrogen by eating plants and other animals

Nitrogen CycleNitrogen Cycle(Nitrogen is required for the manufacture of

amino acids and nucleic acids)

The stages in the assimilation of nitrogen:

Nitrogen Fixation: Some bacteria turn N2 to NH4

+

Lightning and radiation turn N2 to N03-

Nitrification: Some bacteria turn NH4

+ to N02- then to N03

-

Nitrogen CycleNitrogen Cycle(Nitrogen is required for the manufacture of

amino acids and nucleic acids)

Release

Denitrifying bacteria change N03- back to N2

Animals excrete NH4+

or NH3 in their urine

Nitrogen CycleNitrogen Cycle(Nitrogen is required for the manufacture of

amino acids and nucleic acids)

Nitrogen Cycle

Phosphorus CyclePhosphorus Cycle(Phosphorus is required for the manufacture

of ATP and all nucleic acids)

Reservoir sediment and rocks contain phosphorus. When

they erode, they transfer phosphorus into the water and soil

Phosphorus CyclePhosphorus Cycle(Phosphorus is required for the manufacture

of ATP and all nucleic acids)

Assimilation

plants absorb inorganic phosphate from the soil

animals obtain organic phosphorus when they eat plants or other animals

Phosphorus CyclePhosphorus Cycle(Phosphorus is required for the manufacture

of ATP and all nucleic acids)

Release plants release phosphorus when they decompose

animals release phosphorus when they decompose animals excrete phosphorus in their waste products

Phosphorus Cycle