QUESTION

Easy

Environment & Ecology

Prelims 2021

In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?

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Explanation

The Phosphorus Cycle is unique among major biogeochemical cycles because it does not involve a gaseous phase. Instead, phosphorus primarily moves through the lithosphere (rocks), hydrosphere (water), and biosphere (organisms).

  • Weathering of Rocks: The main source of phosphorus in this cycle comes from the weathering of phosphate-rich rocks. Over time, geological processes break down these rocks, releasing phosphate ions (PO₄³⁻) into the soil and water.

  • Absorption by Plants: Plants absorb phosphorus from the soil, and it moves up the food chain as herbivores and carnivores consume plants and other organisms.

  • Return to the Soil: When organisms die, decomposition releases phosphorus back into the environment, where it can re-enter the cycle.

    Phosphorus Cycle

    Phosphorus Cycle

  • Carbon Cycle: The main source of carbon is atmospheric CO₂, released by respiration, combustion, and volcanic activity.

    Carbon Cycle

    Carbon Cycle

  • Nitrogen Cycle: Nitrogen is primarily cycled through the atmosphere, with nitrogen fixation (by bacteria) being a key process.

    Nitrogen Cycle

    Nitrogen Cycle

  • Sulphur Cycle: Sulfur is mainly released from volcanic eruptions, decaying organic matter, and fossil fuel combustion, rather than rock weathering.

    Sulphur Cycle

    Sulphur Cycle

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