7.4 - Atmospheric CO2 and PM

Question 1

Natural Sources of Air Pollutants

Answer 1

• lighting strikes: Convert N2 in atmoshere to NOx
• Forest fires: CO, PM, NOx
  - combustion of biomass also released CO2 and H2O vapor (GHG)
• Plants (especially confiers): plants emit VOCs
• Volcanoees: SO2, PM, CO, NOx

Question 2

Natural Sources of CO2 and PM

Answer 2

• Repiration: all lliving things release CO through respiration
• Natural PM sources: sea salt, pollen, ash from forest sires, and volcanoes dust (windborne soil)
  - leads to haze (scattering of sunlight and reduces viability)
• Aerobic decomposition: decomposition of organic matter by bacteria and decomposers in the presence of oxygen -> releases CO2
• Anaerbic decomposition: decomposition of organic matter by bacteria and decomposers in low or oxygen-free conditions -> releases CH4 (methane)

Question 3

PM10 vs PM2.5

Answer 3

• Particulate Matter: solid or liquid particles suspended in air (also referred to as ‘particulates’)

PM10 (<10 micrometers)
- particles or droplets like dust, pollen, ash, or mod
- too small to be filtered out by nose hairs and trachea cilia; can irritate respiratory tract and cause inflammation

PM2.5 (<2.5 micrometers)
- particles from combustion (especialy veicles) smaller dust particles
- more likely to travel deep into the lungs due to smaller size
- associated with chromic beonchitis and increased risk of lung cancer