Calcium Cycle

Calcium enters from biosphere in dust or from organisms. Like phosphorous, there is no gaseous state so it does not stay in the atmosphere. When animals die, the calcium in their bodies are decomposed and go into soil.

In the earth crust calcium makes up about 3.4% of the mass, exceeded by iron - 4.7%, aluminum - 7.5%, silicon -25.8 and oxygen 49.5%.

Calcium, one of the elements of the original crust of earth, is today found in igneous rocks as calcium silicate and in sedimentary rocks and metamorphic rocks as calcium carbonates.

The process involve in weathering rocks, especially where some acids is present, as carbon dioxide dissolved in water or from growing lichens, are able to free some calcium from its sequestered location and send it on its way as a cations attracted to a water molecules through run offs.

Now, aquatic resources, aquatic plant, phytoplankton will consume the calcium present in the water in the form of calcium ions.

As the organisms die their hard or mineralized parts, shell, fall to the ocean floor and accumulate and dissolve. Shells and such which fall to the bottom of the deep part of the ocean are most often re-dissolved because the deeper waters can hold more CO2.

How does calcium get back on the land after it has done its time in the ocean?

Obviously some is brought back as birds, animals, and man harvest sea-foods, especially shellfish and eat it on land. The majority of calcium however takes a different route back to the land. It takes a ride on a major geologic process. The movements of crustal plate and continental land masses with various up thrust has brought many of this accumulated CaCO3 deposits to or near the surface as limestone or marble.