Environmental Chapter 2
Biogeochemical Cycles
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Most things in nature get recycled and are
used over again
Three common cycles
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Water cycle
Carbon cycle
Nitrogen cycle
The Water Cycle
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Water moves through the biotic and abiotic factors in the
environment
Ways water can move:
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Precipitation
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water moves from the atmosphere to the land in the form
of snow, rain, sleet and hail.
During condensation water cools and condenses,
precipitation forms
About 91% falls into oceans. The rest falls on land to
replenish the fresh water supply
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Evaporation
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Water moves from the land to the atmosphere
Transpiration is when water moves from living things to
the atmosphere. It is a form of evaporation
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Ground Water – when precipitation seeps into the
ground and becomes part of the water table
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Runoff
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Water that flows on top of the ground
The Carbon Cycle
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All living things have carbon in them
All carbon that is on earth has been here
since the earth was formed
Ways that carbon moves through the
environment
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Photosynthesis – carbon gets taken out of
the air and used by producers to make food
Respiration- carbon gets put back into the air
by animals when they exhale
Decomposition – breakdown of dead
materials by bacteria and fungi
Combustion – carbon in fossil fuels is
released while burning
The Nitrogen Cycle
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78% of the earth’s atmosphere is nitrogen
Organisms cannot use nitrogen directly from
atmosphere
Nitrogen fixation- when bacteria in the soil change
atmospheric nitrogen gas into usable nitrogen
Lightening can also fix nitrogen
Denitrification-different bacteria change usable
nitrogen into atmospheric nitrogen gas