Cycling of Matter & The Climate System

Cycling of Matter & The Climate System

  • Biogeochemical Cycles

    • Define biogeochemical cycles:

    • Natural cycling of matter and energy between abiotic (non-living) and biotic (living) environments.

    • Importance of biogeochemical cycles:

    • Matter is held for longer periods in stores or reservoirs, facilitating essential ecological processes.

    • Human activities can disrupt the natural balance of these cycles, leading to environmental issues.

The Carbon Cycle

  • Carbon Stores

    • Define carbon stores: Locations where carbon is stored in various forms.

    • Major carbon stores and their respective amounts of carbon (in gigatonnes):

    • Marine sediments and sedimentary rock: Between 68 to 100,000,000 gigatonnes

    • Oceans: 39,000 gigatonnes

    • Fossil fuels: 3,300 gigatonnes

    • Vegetation, soil, and organic matter: 2,115 gigatonnes

    • Atmosphere: 750 gigatonnes

Global Carbon Budget

  • Definition: The global carbon budget describes the exchanges of carbon across different parts of the carbon cycle.

  • Impact of Human Activities:

    • Human activities affect the carbon cycle by altering the relative amounts of carbon stored in various reservoirs, which can lead to climate change and ecological disruption.

Nitrogen Cycle

  • Nitrogen

    • Composition of atmosphere: About 80% nitrogen gas (N2).

    • Process to enter the nitrogen cycle: N2 must be converted to other forms, such as ammonium (NH4) and nitrate (NO3-), to participate in biological processes.

    • Nitrogen Fixation:

    • Occurs naturally through:

      • Nitrogen-fixing bacteria in soil

      • Lightning strikes

    • Industrial process:

      • Using high temperatures and pressures to convert nitrogen into ammonia (NH3) for use in fertilizers.

Human Activity & Nitrogen

  • Impact on the Nitrogen Cycle:

    • Agricultural practices:

    • Use of fertilizers adds nitrogen to soils and enhances nitrogen fixation.

    • Environmental consequences:

    • Runoff from agricultural fields can add excessive nitrogen to waterways.

      • Resulting in ecological issues such as algal blooms and “dead zones” in aquatic ecosystems.

    • Other sources:

    • Farming and the combustion of fossil fuels also contribute to nitrogen accumulation in the atmosphere.