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Phosphorous Cycle

Phosphorous Cycle. Describes the routes that phosphorus atoms take through the environment “Sedimentary cycle” Most P is in rocks & released by weathering

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Phosphorous Cycle

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  1. Phosphorous Cycle • Describes the routes that phosphorus atoms take through the environment • “Sedimentary cycle” • Most P is in rocks & released by weathering • P moves slowly from phosphate (PO43-) deposits on land & in shallow ocean sediments to living organisms & then back into the ocean & land

  2. Phosphorous Cycle • No significant atmospheric component • b/c P & its compounds are not gases (under normal Earth conditions b/c it is a metal) • Only in atmosphere as small particles of dust & sea-spray • Relatively slow cycle • compared to other cycles with gaseous components • On human time scale more P flows from land  ocean

  3. Phosphorous Cycle • Typically found as phosphate salts • containing phosphate ions (PO43-) • in terrestrial rock & ocean sediments • With naturally low environmental concentrations, phosphorus is a limiting factor for plant growth • Most soils contain little phosphate • limiting factor for plant growth on land • unless applied as fertilizer • In freshwater phosphate salts only slightly soluble • limits growth of aquatic producers • Addition of phosphate compounds greatly increases productivity • Causes eutrophication

  4. Stores/sinks of Phosphorous • Uptake of PO43- by autotrophs (& consumption by herbivores, etc.) • Biosynthesis in ATP, ADP, DNA, cell membranes • Dissolved in water (in soil, oceans, freshwater) • Settling & formation of aquatic sediments • Rock formation

  5. Sources of Phosphorous • Uplift, weathering, & erosion of rock • Volcanic eruptions • Mining • Leaching through soil & runoff • Pollution • fertilizers • Detergents • Decomposition of wastes/feces & organic matter (back into soil) • Excretion (guano) • Upwelling of PO43- rich water

  6. Human Effects on the Phosphorous Cycle • Remove large amounts of phosphate • to make fertilizer • mining • Reduce phosphorous in (tropical) soils • by clearing forests • Add excess phosphates to aquatic systems • from runoff of animal wastes, fertilizers, detergents • eutrophication

  7. The Phosphorus Cycle

  8. The Phosphorus Cycle

  9. Phosphorus Cycle

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