1. THE CYCLES OF EARTH
Carbon Cycle
Nitrogen Cycle
Water Cycle

2. THE CYCLING OF MATTER
BIOGEOCHEMICAL CYCLES: the movement of chemicals through biological & geological (living & nonliving) parts of an ecosystem.
*Earth is a closed system. Nothing enters or leaves.

3. WATER CYCLE (Hydrologic)
Big picture: Water moves between the
hydrosphere (oceans & lakes),
the atmosphere (water vapor & clouds)
& the geosphere (ground).
Details:
1) The sun drives the water cycle & causes evaporation of surface water & transpiration from plants.
2) The water vapor condenses forming clouds & precipitation.
3) The water falls as precipitation, where it either sinks into the ground OR it enters lakes/rivers as surface runoff.

4. CARBON CYCLE Big picture: The transformation & movement
of carbon between the atmosphere, living and
dead organisms, and carbon sinks.
Details:
Plants use energy from the sun to convert CO2 into organic matter through photosynthesis.
It is transferred to animals which eat the plants.
Carbon is released into the atmosphere by respiration, decomposition, & burning fossil fuels.
Forests also “store” carbon.

5. WAYS HUMANS ALTER THE CARBON CYCLE
Deforestation: removing trees that release carbon dioxide from the atmosphere. Fewer trees mean less carbon dioxide is being absorbed.
Burning of fossil fuels in industry & vehicles: Carbon is a by-product of combustion. The amount of carbon dioxide in the atmosphere has been rising. Some say it is contributing to global warming.

6. NITROGEN CYCLE Big picture: Large amounts of nitrogen are found
in the atmosphere and is crucial for
living organisms.
(nucleotides & amino acids).
Details:
Nitrogen-fixing bacteria convert Nitrogen (N2) gas from the atmosphere to a form plants can use.
Animals get nitrogen by eating plants or other animals.
When the organism & it’s wastes decompose, the nitrogen is released into the soil.
Nitrifying bacteria release it to the atmosphere.

7. WAYS HUMANS ALTER THE NITROGEN CYCLE
The rate of nitrogen fixation has increased since the 1950s.
Fertilizers: contain nitrogen.
Burning of fossil fuels: releases nitrogen.
Destruction of forests & wetlands: release nitrogen.