Q. 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?

• carbon cycle
• Nitrogen cycle
• Phosphorus Cycle
• Sulphur Cycle

Answer: c) Phosphorus Cycle

Notes:

• The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.
• Phosphorus moves in a cycle through rocks, water, soil and sediments and organisms.
• Over time, rain and weathering cause rocks to release phosphate ions and other minerals.
• This inorganic phosphate is then distributed in soils and water.
• Plants take up inorganic phosphate from the soil.
• Phosphorus is an essential nutrient for animals and plants.
• It plays a critical role in cell development and is a key component of molecules that store energy, such as ATP (adenosine triphosphate), DNA and lipids.
• The global phosphorus cycle includes four major processes:
  • Tectonic uplift and exposure of phosphorus-bearing rocks such as apatite to surface weathering.
  • Physical erosion, and chemical and biological weathering of phosphorus-bearing rocks to provide dissolved and particulate phosphorus to soils, lakes and rivers.
  • Riverine and subsurface transportation of phosphorus to various lakes and run-off to the ocean.
  • Sedimentation of particulate phosphorus (e.g., phosphorus associated with organic matter and oxide/carbonate minerals) and eventually burial in marine sediments.