Carbon Cycle and Nutrient Cycles and Greenhouse Gases

Nutrient Cycles:

  • Nutrients are chemicals required for growth and life processes

    • Carbon, oxygen, hydrogen, nitrogen, phosphorus

  • Each nutrient has sources, stores and sinks to flow in and out of stores in nutrient cycles

  • Without interference the amount of nutrients flowing into the store equals the amount of nutrients flowing out, making it balanced

Carbon Stores:

Carbon atoms are a fundamental unit in cells of all living things.

  • Can be stored in many locations

  • Short term storage

    • Aquatic and terrestrial organisms

    • CO2 in the atmosphere

    • Top layers of the ocean

  • Long term storage

    • Middle and lower ocean layers

    • Coal, oil and gas deposits in land and ocean sediments (ancient organic matter buried deep underground that transformed into carbon rich deposits)

Carbon Cycle:

  • Cycled through interactions between living and nonliving things

  • Photosynthesis+Respiration: plants pull CO2 gas from the atmosphere, organisms release it back through breathing

  • Death and Decomposition: When organisms die and decompose, CO2 returns to the atmosphere

  • Geosphere: when remains get buried under sediment layers, carbon enters the ground and eventually becomes fossil fuels

Human Activities:

  • Human activities upset the natural balance by releasing stored carbon

  • land clearing, agriculture, urban expansion, mining industry, motorized transportation and burning fossil fuels can increase the levels of nutrients by reintroducing carbon from stores and reducing plants that can absorb and convert Co2

  • Extra carbon dioxide in the air traps heat in the atmosphere leading to global warming and climate change

Global Warming and Climate Change

  • CO2 is a greenhouse gas (absorbs solar energy in Earth’s atmosphere)

  • Global warming: An increase in the average temperature of Earth’s surface

  • Global climate change: A long term change in earth’s climate

  • Causes can be natural (volcanic activity, change in ocean and atmospheric circulation and Earth’s orbit)

  • Causes can be human (burning fossil fuels)

Effects of excess carbon in the carbon cycle

  • Causes Earth’s temperature to rise from 0.56-0.92 degrees celsius in the last 100 years causing a chain reaction

  • Melt sea and land ice: led to destruction of habitats for polar organisms, increased local flooding and release of methane gas from melting permafrost

  • Rising sea level: Some island have gone underwater, saltwater gets into drinking supply, coastal flooding and destruction of wetlands

  • Changing ocean chemistry: Ocean becomes more acidic because it absorbs more cO2 from the air, an acidic and warming ocean and destroy corals and coral reefs (acidity dissolves the organisms’ shells)

Naturally occurring greenhouse gases:

  • Water vapour

  • CO2

  • Methane

  • Nitrous oxide

Human activities release extra:

  • CO2: released when fossil fuels (oil, natural gas, coal) are burned

  • Nitrous oxide: enters the atmosphere when fertilizer is applied to crops

  • Methane: Released in large amounts by herd of cattle