Oxygen+cycle


 * __Oxygen cycle__**

__where is oxygen found?__ atmosphere oceans rocks
 * all living organisms**

never found as oxygen atoms... may be O2 --> oxygen in air 03--> ozone CO2 CO3 H2O Fe2O3 C6H12O6 A large proportion of Earth's oxygen is found in rocks. Organisms like lichen are able to break down the rocks over thousands of years and release the nutrients into the soil.

Phosphorus is a component of DNA and ATP molecules so is essential for life. Phosphorus enters the environment from ROCKS when they weathered. Phosphate ions are ABSORBERD from when they are weathered. Phosphate ions are LEACHED from the rocks into the soil. PLANTS absorb the phosphorus and make ORGANIC compounds. ANIMALS then obtain the phosphorus. The phosphorus “cycle” is not a true cycle as much is lost because it ends up at the bottom of the OCEAN. AND here, it is useless.  __Describe the problem of this loss of phosphorus __ Ocean is a phosphorus sink It is used up too quick and it cannot be replaced. We may end up without phosphorus. __Human effect: __farmers apply phosphorus to the land in FERTILISER. Excess may end up in rivers and lakes and add to the problem and lakes and add to the problem of EUTROPHICATION