The geochemical cycle refers to the continuous movement and transformation of chemical elements and compounds between the Earth's various reservoirs, including the atmosphere, hydrosphere, lithosphere, and biosphere. It plays a crucial role in maintaining the balance and sustainability of the Earth's ecosystems. The major components of the geochemical cycle mentioned in the syllabus include:


The atmospheric cycle involves the movement of various elements and compounds in the Earth's atmosphere. Key components of this cycle include:

- Carbon Cycle: It involves the exchange of carbon dioxide (CO2) between the atmosphere, plants, and the ocean through processes such as photosynthesis, respiration, and oceanic absorption.

- Nitrogen Cycle: It encompasses the transformation of nitrogen gas (N2) into forms that can be utilized by living organisms, such as ammonia (NH3) and nitrate (NO3-). This cycle involves processes like nitrogen fixation, nitrification, and denitrification.

- Oxygen Cycle: It involves the exchange of oxygen (O2) between the atmosphere and living organisms through processes like respiration and photosynthesis.


The hydrospheric cycle refers to the movement of water and its associated elements and compounds within the Earth's hydrosphere, including oceans, rivers, lakes, and groundwater. Key components of this cycle include:

- Hydrological Cycle: It involves the continuous circulation of water between the atmosphere, land, and oceans through processes like evaporation, condensation, precipitation, and runoff.

- Water Quality Cycle: It encompasses the transport, transformation, and cycling of various dissolved substances and pollutants within water bodies, impacting their quality and the ecosystems they support.


The lithospheric cycle involves the movement of chemical elements and compounds within the Earth's crust and upper mantle. Key components of this cycle include:

- Rock Cycle: It encompasses the transformation of rocks through processes like weathering, erosion, deposition, and lithification, leading to the formation of sedimentary, metamorphic, and igneous rocks.

- Tectonic Cycle: It involves the movement of Earth's tectonic plates, leading to processes such as volcanic activity, mountain formation, and plate subduction, which have significant geochemical implications.


The biospheric cycle refers to the movement of elements and compounds within the Earth's living organisms and ecosystems. Key components of this cycle include:

- Nutrient Cycle: It involves the cycling of essential elements like carbon, nitrogen, phosphorus, and sulfur within living organisms through processes like photosynthesis, respiration, and decomposition.

- Food Chain Cycle: It encompasses the transfer of energy and nutrients through various trophic levels within ecosystems, highlighting the interdependence and cycling of elements among different organisms.

Overall, the geochemical cycle is a complex and interconnected system that involves the movement and transformation of elements and compounds among the Earth's various spheres. Understanding these major components is crucial for comprehending the Earth's biogeochemical processes and their implications for environmental sustainability.