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Nutrient Cycles

Nutrient Cycles. Eutrophication Nitrogen Chemical Forms in the Aquatic Environment Chemical Transformations Cycle f-ratio Carbon. Nutrient Cycles and Eutrophication. Light penetration with depth Mixing and stratification Phytoplankton nutrient use Ocean circulation. Eutrophic.

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Nutrient Cycles

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  1. Nutrient Cycles • Eutrophication • Nitrogen • Chemical Forms in the Aquatic Environment • Chemical Transformations • Cycle • f-ratio • Carbon

  2. Nutrient Cycles and Eutrophication • Light penetration with depth • Mixing and stratification • Phytoplankton nutrient use • Ocean circulation

  3. Eutrophic • Refers to areas that contain high nutrient concentrations and support high biological productivity Eastern Boundary Currents Upwelling

  4. Eutrophication • An increase of nutrients in a system (N or P) which promotes excessive plant growth (and decay) and is likely to cause severe reductions in water quality Increase in nutrient loading

  5. Experimental Lakes Area

  6. Point and Nonpoint sources of chemical inputs

  7. Algal Bloom in Lake

  8. Before After

  9. Adverse effects of eutrophication on lakes, reservoirs, rivers and coastal marine waters • Increased biomass of phytoplankton • Toxic or inedible phytoplankton species • Increases in blooms of gelatinous zooplankton • Increased biomass of benthic and epiphytic algae • Changes in macrophyte species composition and biomass • Decreases in water transparency • Taste, odor, and water treatment problems • Dissolved oxygen depletion • Increased incidences of fish kills • Loss of desirable fish species • Reductions in harvestable fish and shellfish • Decreases in perceived aesthetic value of the water body

  10. New species invasion • Eutrophication may cause competitive release - nutrient normally limiting ↑↑. • ↑ nitrogen might allow new, competitive species to invade and outcompete original inhabitant species

  11. The changes in nutrient levels and biology can directly affect humans: •    The water can be injurious to health •    The amenity value of the water may decline •    Increased vegetation may impede water flow and navigation •    Commercially important species of fish may disappear •    Treatment of drinking water may be difficult and supply can have an unacceptable taste or odor

  12. Prevention of eutrophication

  13. The main effects caused by eutrophication: 1.     Species diversity decreases and the dominant biota changes 2.     Plant and animal biomass increase 3.     Turbidity increases 4.     Rate of sedimentation increases, shortening the lifespan of the lake 5.     Anoxic conditions may develop

  14. Gulf of Mexico

  15. Caspian Sea

  16. Algal Bloom

  17. Oligotrophic Lake Eutrophic Lake

  18. Oligotrophic Lake Eutrophic Lake

  19. Chemical Forms – Nitrogen

  20. NO32- (Nitrate) NO2- (Nitrite) NH4+ (Ammonium) CO(NH2) 2 (Organic, Urea) N2 (Dissolved gas) N2O (Nitrous Oxide) Chemical Forms – N

  21. Annual Surface Nitrate Concentration

  22. The Marine Nitrogen Cycle

  23. The Marine Nitrogen Cycle *

  24. The Marine Nitrogen Cycle * *

  25. The Marine Nitrogen Cycle * * *

  26. NO32- (Nitrate) →NO2- (Nitrite) → NH4+ (Ammonia) Heterotrophic microbes (anerobic) Denitrification Nitrification NH4+ (Ammonia) →NO2- (Nitrite) → NO32- (Nitrate) Heterotrophic microbes (aerobic)

  27. Nitrate Uptake into the Cell Reduction steps NO3 NO3 NO2 NH4 Proteins Diffusional Gradient Reduction steps: Reduced forms of nitrogen are ‘preferred’ Phytoplankton other Autotrophs - Assimilatory N Reduction

  28. N2 Fixation Rivers Deposition Phytoplankton Nitrate Euphotic Zone Upwelling Mixing Vertical Flux PON DIN

  29. f-ratio New Production New + Regenerated Production Upwelling Zone 0.8 Gyre 0.1 Global Average < 0.5

  30. Sediment traps to catch sinking particles

  31. Sustainable yields

  32. N2 Fixation Rivers Deposition Fishing Phytoplankton Nitrate Euphotic Zone Upwelling Mixing Vertical Flux PON DIN

  33. Oligotrophic gyres Upwelling regions New Production

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