the end of this Lecture, students will be able to
• Discuss different Biogeochemical cycles
Bio-Geo- Chemical Cycles
• Hydrological Cycle
• Carbon cycle
• Oxygen Cycle
• Nitrogen Cycle
• Sulfur Cycle
Nutrients, unlike energy are recycled in
the ecosystem. The Producers of an ecosystem take up several basic nutrients
from their non-living ecosystem. Materials are in limited quantity in the
earth’s system and to keep the system going continuously, these materials get
transformed into biomass of the producers.
Thus they are utilized by the consumer
population and are ultimately returned to the environment with the help of
reducers or decomposers.
The unique method evolved in nature is
recycling materials continuously is by linking them in cycle changes.
This cyclic exchange of nutrient material
between the living organisms & their non-living environment is called Bio-
As indicated by the name the nutrients are
circulated through life (bio) and through earth (geo) repeatedly (cycle).
• The natural flow of water through various
components of environment resulting in the global circulation is called water
in Hydrological Cycle:
Evaporation: Surface water is heated by sun and
evaporates to become water vapour, water vapour floats in the air.
Condensation: As water vapour rises into the air it
gradually cools and condenses and become minute droplet of water.
Clouds: Tiny droplets of water together forms
Precipitation: The fall of water on earth surface
in any form of water it may be in the form of dew, drizzle, rain is known as
Runoff: Precipitated rain water accumulates and
flows on the surface and sub- surface towards rivers, streams, and underground
stores and ultimately reaches to sea.
Percolation & infiltration: The process of
stored water flowing under earth, merge to the ground water source is called
percolation and infiltration
• Transpiration: The water which directly evaporates from leaves of plants is called
Completion of Cycle: All the water bodies continues
its journey towards the natural slope and meet the sea where the cycle starts