The term "biogeochemical" tells us that biological, geological and chemical factors are all involved. The circulation of chemical nutrients like carbon, oxygen, nitrogen, phosphorus, calcium, and water etc. through the biological and physical world are known as biogeochemical cycles. In effect, the element isrecycled, although in some cycles there may be places (calledreservoirs) where the element is accumulated or held for a long period of time (such as an ocean or lake for water).