Enduring Understanding:

• Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective:

• Describe natural sources of CO2 and particulates.

Essential Knowledge:

• CO2 appears naturally in the atmosphere from sources such as respiration, decomposition, and volcanic eruptions.

• There are a variety of natural sources of particulate matter.

Anthropogenic vs. Natural Pollution Sources

• Air pollution is any substance in the atmosphere that has harmful effects on people, ecosystems, or infrastructure and the economy

• Sources can be anthropogenic or natural

  • The primary focus of unit 7 is air pollutants from human activities and their effects

  • This topic focuses on natural sources

Carbon Dioxide

Sources

• Respiration

• Ocean outgassing/diffusion

• Decomposing biomass

• Geological processes like volcanoes

• Ecosystem disturbances like wildfires

• The good thing is that these natural sources of carbon are fast carbon

A Pollutant?

• Natural emissions are a major contributor to atmospheric CO2 levels, but natural processes are also sinks of carbon dioxide

• The net effect of natural CO2 sources and sinks in minimal

  • Natural sources typically emit carbon that was recently in the atmosphere anyway

  • Burning fossil fuels for power, transportation, and petroleum products add excess carbon dioxide to the atmosphere

• CO2 is a greenhouse gas necessary to support life and maintain global temperatures

  • Excess CO2 that disrupts ecosystems, health, and the economy is a pollutant

• If we breathe some CO2, it does nothing to us

  • So it is not directly harmful to humans or animals

  • It does, however, have detrimental effects when too much is in the atmosphere

Particulate Matter (PM)

• PM is solid and liquid particles in the air that are small enough to be inhaled

• Categorized based on the size in microns

• Particulate matter under 10 microns is inhalable

  • PM10 is between 2.5 and 10 microns in diameter

  • These are associated with concerns about the eyes, nose, and throat

• PM2.5 is under 2.5 microns in diameter

  • Concerns about the inner functions of the lungs

• There are also PM1 and PM0.1 that can enter the bloodstream

Natural Sources

• Pollen, spores from plant or fungi

• Bacteria

• Dust and dust mites

• Airborne soil

• Sea salt

• Can come from geological processes like volcanic dust and sulfates

• Also comes from wildfire soot and ash