What is the purpose of the biochemical cycles

Bigeochemical cycles are variety of biological, geological, and chemical processes.

Many elements cycle through ecosystems,
organisms, air, water, and soil. Many of these are trace elements. Other elements, including carbon, nitrogen, oxygen, hydrogen, sulfur, and phosphorus are critical components of all biological life.

Because these elements are key components of life, they must be available for biological processes. The biogeochemical cycles transport and store these important elements so that they can be used by living organisms. 

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They formed the oceans.  as they melted water was formed and the water made the oceans