Unit 7: AtmosphericPollution

APESDr. Sowell

Structure of the Atmosphere

Atmospheric Composition• Nitrogen: 78%• Oxygen: 21%• Argon: 0.93%• Carbon dioxide: 0.04%

• Other: Ne, He, H2O(g)• Plus pollutants

- air more dense at surface- air pressure decreases with altitude

Structure of the AtmosphereTroposphere:•0-7 mi•T with altitude•75-80% of total air mass•Main gases:

•N2 (78%)•O2 (21%)•some H2O(v) & CO2(g)•location of biogeochemical cyclingweather/climate

Structure of the Atmosphere

Stratosphere:• 18-48 km/12-30 mi• T increases with altitude• calm, less turbulent air (commercial

airplanes)• Location of stratospheric O3

Ozone (O3)“Good Up High … Bad Nearby”

TroposphericOzone

•air pollutant•man-made "secondary" air pollutant that is significant component of photochemical smog

Stratospheric Ozone

•"global sunscreen"blocks out 95% of sun's harmful UV radiation•sunburn, cancer, etc..• necessary for life on Earth•natural

Ozone Layer

Stratospheric Ozone•"global sunscreen" blocks out 95% of sun's harmful UV radiation•sunburn, cancer, etc..• necessary for life on Earth

Effects of Stratospheric Ozone Depletion• Higher levels of UV-radiation hitting the

earth• Eye cataracts (lens cloudy with damaged

proteins)• Skin cancer (DNA mutation)• Weakened immunity• May disrupt ecosystems (photosynthesis

disruption or DNA mutations)• May damage crops and forests

Ozone Depletion in the Stratosphere

• Ozone thinning/hole:• First identified in 1985 over

Antarctica• Caused by CFCs

(chloroflourocarbons)

Stratospheric Ozone Depletion

Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing

agents for foams and packing materials, as solvents, and as refrigerants.

Stratospheric Ozone Depletion

Recovery of the Stratospheric Ozone Layer

• Montreal Protocol (1987)• Global reduction and eventual

phase out of all ozone destroying chemicals (e.g., CFCs)

• Satellite pictures now indicate that ozone layer was slowly recovering

• Full recovery will not occur until 2060

https://youtu.be/aU6pxSNDPhsOzone Depletion | National Geographic

Air Pollution

Air Pollution Super-Villains1. SO2 – sulfur dioxide2. NO2 – nitrogen dioxide3. VOC – volatile organic compound4. CO – carbon monoxide5. Acid Deposition – H2SO4 and HNO36. O3 – tropospheric ozone7. Hg – mercury8. PM – particulate matter9. Rn – radon10.Tobacco Smoke11.Pb – lead12.CH2O - Formaldehyde13.Mold14.Asbestos15.Photochemical Smog