2. Cycles of Matter  Also called biogeochemical cycles  These cycles are nature’s way of recycling because… Matter is always conserved  The three main cycles are water, carbon, and nitrogen

3. The Water Cycle  Water is constantly moving between biotic and abiotic things.  Water can move through the environment in four main ways 1.Precipitation—movement of water from the atmosphere to the land Includes rain, snow, sleet, hail Approx. 91% falls on the ocean; the other 9% falls on land to replenish the fresh water supply.

4. The Water Cycle 2.Evaporation—Water moving from the land to the atmosphere Transpiration—a form of evaporation from the surface of living things Condensation—When water vapor cools to form a liquid (falls as precipitation)

5. The Water Cycle 3.Ground Water—when water seeps into the ground, where it is stored in places like underground caverns. Provides water to the soil, streams, rivers, and oceans 4.Runoff—Water that does not seep into the ground, but rather flows on top of it

7. The Carbon Cycle  Every living thing contains carbon.  Carbon also moves through the environment in four main ways.

8. The Carbon Cycle  Photosynthesis—producers use carbon dioxide (CO 2 ) from the air to make food for themselves  Respiration—when carbon is returned to the atmosphere as animals exhale  Decomposition—when bacteria and fungi break down dead materials to release carbon  Combustion—when fossil fuels are burned, carbon is released

10. The Nitrogen Cycle  Approx. 78% of Earth’s atmosphere is nitrogen gas.  However, most organisms cannot use this form directly from the atmosphere  Nitrogen Fixation—bacteria in the soil are able to convert atmospheric nitrogen into a usable form for plants and animals Lightning can also “fix” nitrogen  Denitrification—other bacteria do the opposite: convert usable nitrogen back into atmospheric nitrogen