The calcium is a mineral that participates in the formation of shells and exoskeletons, in invertebrates; and teeth and bones, in vertebrates; in addition to participating in the activation of enzymes, blood clotting, muscle contraction, plant cell wall composition, among others, that is why the calcium cycle is important for all living beings.
Rocks are the main sources of calcium in nature, so it is only possible to find calcium salts dissolved in water and soil through mechanical, chemical and biological processes, which cause the destruction of rocks, forming the soils.
One of the factors that cause the destruction of rocks is rain, which has CO2 dissolved in its drops. When falling under the rocks, this rain that has become acidic due to the presence of CO2 causes the rocks to erode and release Ca 2+ and HCO 3- , among other substances that can be taken to the ocean.
When these products (Ca 2+ and HCO 3- ) reach the sea, they are used by animals that use them to make their shells. From the moment these animals die, their shells and exoskeleton are deposited on the bottom of the oceans and are associated with other residues, until, after a long time, they form sedimentary rocks.
Through tectonic movements, these sedimentary rocks can be taken to places where there are changes in temperature and pressure, until they reach the earth’s crust. In the crust, from the weather, the calcium in these rocks dissolves in the soil and in the water, becoming available to aquatic plants and animals. Other animals manage to obtain calcium through the food chain.
When animals and plants die, all calcium-containing structures decompose, and calcium salts dissolve in water and soil, making them available to plants and animals, thus completing the calcium cycle.