Lesson 10: Bio-geo-chemical cycles


Nutrients are recycled in the ecosystem. There are about 40 chemical elements considered to be essential for living organisms. Materials are in limited quantity in the earth’s system and to keep the system going continuously the only possibility is to regenerate the materials.


The cyclic movement of elements between living organisms (the biotic phase) and their non-living (abiotic) surroundings (eg; rocks, water, air etc.) is termed biogeochemical cycle.

The macro-nutrients are C, H, O, P, K, N, S, Mg, Ca etc. which have cycles with atmosphere while micro-nutrients like Cu, Fe, Co etc are soil based form edaphic cycles. The bio-geo chemical cycles are of two varieties – sedimentary and gaseous cycles. In sedimentary cycles, the main reservoir is the soil, eg. Sulphur and phosphorus cycles; the gaseous cycles have their main reservoir of nutrients in the atmosphere and oceans, eg: oxygen, carbon and nitrogen cycles. Both cycles involve the biotic and abiotic systems. Both are driven by the flow of energy and both are tied up with the water cycle or the hydrologic cycle.


Last modified: Thursday, 29 December 2011, 7:35 AM