Environmental Science and Engineering

• Ecosystem


  A community of living organisms (biotic) interacting with each other and their physical environment (abiotic)
• What keeps us and other organisms alive

  • The flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity
• Major components of Earth's life support systems

  • Atmosphere
  • Hydrosphere
  • Geosphere
  • Biosphere
• Three factors that sustain the Earth's life

  • One-way flow of high-quality energy from the sun
  • Cycling of nutrients
  • Gravity
• Producers


  • Organisms that make the nutrients they need from compounds and energy obtained from their environments (e.g. green plants, algae, phytoplankton)
• Consumers


  • Organisms that cannot produce the nutrients they need through photosynthesis or other processes (e.g. herbivores, carnivores, omnivores)
• Decomposers


  • Organisms that release nutrients from the dead bodies of plants and animals and return them to the soil, water, and air for reuse by producers
• Detrivores


  • Organisms that feed on the wastes or dead bodies of other organisms
• Ecosystems are supported by the energy from the sun
• Food chain


  A sequence of organisms, each of which serves as a source of food or energy for the next
• Food web


  A complex network of interconnected food chains
• Energy transfer through food chains and food webs is not very efficient, there is a decrease in the amount of chemical energy available to organisms at each succeeding feeding level
• Net primary productivity (NPP)


  Measures how fast producers can produce the chemical energy that is stored in their tissue and potentially available to other organisms (consumers) in an ecosystem
• Biogeochemical cycles


  • Carbon and oxygen cycle
  • Nitrogen cycle
  • Phosphorus cycle
  • Sulfur cycle
• Nitrogen fixation


  The process of converting N2 into biologically available nitrogen
• Nitrification


  The process that converts ammonia to nitrite and then to nitrate
• Denitrification


  The process that converts nitrate to nitrogen gas, thus removing bioavailable nitrogen and returning it to the atmosphere
• Ammonification


  The process where organisms decompose organic nitrogen and release inorganic nitrogen back into the ecosystem as ammonia
• TYPES OF CONSUMERS

  • primary consumers, or herbivores
  • secondary consumers, or carnivores
  • Omnivores
• Producers sometimes called autotrophs (self-feeders)