7.2 Nutrient cycling

biogeochemical cycles

Nutrient cycles in ecosystems involve biotic and abiotic components

hydrologic cycle

  • essential to all organisms

  • water carries nutrients, gases, and waste

  • influences rate of primary production and decompisition

  • evaporation by solar energy

  • condensation of water vapor into clouds

  • precipitation

  • transpiration (water lost from plants)

  • surface + groundwater flow to ocean

carbon cycle

  • carbon based organic molecules (macromolecules): carbs, proteins, lipids, nucleic acids

  • autotrophs convert atmospheric CO2 into sugars for cellular respiration

  • cellular respiration uses sugars to make energy, byproduct is CO2

  • carbon sinks: fossil fuels, soil, sediment in aquatic ecosystems

nitrogen cycle

  • proteins and nucleic acids use nitrogen

  • majority (78%) of atmosphere is N2

  • nitrogen reservoirs: soil, sediment of aquatic ecosystems, dissolved in water, biomass of living organisms

  • bacteria roles: nitrogen fixation, ammonification, nitrification, denitrification

phosphorous cycle

organic molecules: phospholipids, nucleic acids, atp

resovoirs: sedimentary rocks, soil, dissolved in ocean