The term biogeochemical cycle comes from the cyclical movement of the elements that form biological organisms (bio) and the geological environment (geo) and an intervening chemical change.
The biogeochemical cycle consists of the connection between living and non-living elements. Any living organism decomposes after its death and through a chemical process, the elements resulting from this decomposition are deposited in the biosphere and recycled to be used later by another living organism. The most important biogeochemical cycles are water, oxygen, nitrogen, carbon, phosphorus, and sulfur.
Biogeochemical cycles can be gas cycles, where elements are distributed in the atmosphere and water and then they are going to be reused by living organisms. They can also be sedimentary cycles, where elements are deposited on the earth's crust or on the seabed and remain there for a long time to be recycled later by organisms. Or they can be mixed cycles where the processes of gas cycles and sedimentary cycles are combined.
In this way, matter circulates in and out of ecosystems allowing the formation of life. From an elemental state, matter forms inorganic elements that are reused by living organisms to finally return to the elemental state and start the cycle again. Hence the importance of not altering the natural process of the biogeochemical cycle.
The earth is a closed system where matter does not enter or leave. Substances used by organisms are not “lost”, but they can reach places where they are inaccessible to organisms for a long period of time. However, the material is almost always reused and frequently circulates multiple times, both within and outside ecosystems.
There are three types of interconnected biogeochemical cycles.
In gas cycles, nutrients circulate mainly between the atmosphere (water) and living organisms. In most of these cycles, items are recycled quickly, often within hours or days. The main gas cycles are those of carbon, oxygen and nitrogen.
In nutrient cycles, nutrients circulate primarily in the earth's crust (soil, rocks, and sediments), the hydrosphere, and living organisms. The elements in these cycles are generally recycled much more slowly than in atmospheric cycles, because the elements are retained in sedimentary rocks for a long time, often thousands to millions of years, and do not have a gaseous phase. Phosphorus and sulfur are two of the 36 elements recycled in this way.
In the hydrological cycle; water circulates between the ocean, air, land and living organisms, this cycle also distributes solar heat on the planet's surface.
