(b) : Biogeochemical cycles are of two types: gaseous and sedimentary. In gaseous nutrient cycles, the materials involved in circulation between biotic and abiotic components of biosphere are gases or vapours and the reservoir pool is atmosphere or hydrosphere, $e.g.$, carbon, hydrogen, oxygen, nitrogen, water. In sedimentary nutrient cycles, materials involved in circulation between biotic and abiotic components of biosphere are non­ gaseous and the reservoir pool is lithosphere, $e.g.$, phosphorus, calcium, magnesium. Sulphur has both sedimentary and gaseous nutrient cycles.