The Biogeochemical cycles
The flow of nutrients moves in a continuous cycle from the a biotic to the biotic environment and back again. The pathways along which nutrients move are called biogeochemical cycles.
It is to be noted the ‘bio’ refers to the living part of the cycle in organisms, and ‘geo’ refers to the nonliving part in soils, rocks, and water.
Nutrients enter plants and animals by several routes. Green plants get carbon dioxide from the atmosphere and release oxygen in photosynthesis. Plants and animals exchange gases (oxygen and carbon dioxide) with the atmosphere-ocean environment.
Nutrients are released into the soil by rock weathering which are taken1 up by plant roots, to re-enter the bio part of the cycle.
Nutrients leave living things through respiration. Biogeochemical cycles show how the solid-earth environment is closely connected with living things.
These cyclic movements of chemical elements of the biosphere between the organisms and the environment are referred to as biogeochemical cycles. There are two types of biogeochemical cycles: (i) the gaseous cycle, and (ii) the sedimentary cycle.
In the gaseous cycle the main reservoir of nutrients is the atmosphere and the ocean. In the sedimentary cycle the main reservoir is the soil, the sedimentary and other rocks of the earth’s crust. These two cycles are tied to the water cycle which is known as the hydrological cycle.
