Air Pollution (Smog, Acid Rain, Ozone Depletion) Textbook Unit 7

air pollution

• material added to the atmosphere that can affect climate and harm organisms

natural pollution

• dust storms

• volcanoes

• fires

unnatural pollution

• anthropogenic

• burning fossil fuels

Clean Air Act of 1970

• provided research funds

• regulates criteria pollutants and hazardous air pollutants

• enabled citizens to sue violating parties

• imposed emission limits

Clean Air Act of 1990

• strengthened previous regulations

• introduced emissions tradings for sulfur dioxide

acid deposition (rain)

• sources: transportation, coal electricity, volcanic eruptions, fire, lightning

• primary pollutants: SOx+NOx

  • coal and cars and coal

• secondary pollutants: acids

  • sulfuric acid and nitric acid

• human effects: infrastructure, impacts, limestone

• environmental impacts: leaching metals (Al) in soil, and decreased pH outside range of tolerance

solutions to acid rain

• scrubbers

  • uses a limestone “slurry” (water based) to neutralize acid-producing gases before being released into the atmosphere

  • typically put into exhaust stark

  • industries

• catalytic converters

  • uses platinum, rhodium, and/or palladium as a catalyst to convert NOx into non-regulated gases

  • transportation

where is ozone produced?

• stratosphere: does not contribute to climate change

natural ozone formation

• O+O2 → 03

• O3 ←O+O2

natural ozone destruction

• O3+ UV →O +O2

ozone depletion

• sources: stratosphere, good O3, fridge, ACs, aerosal

• primary pollutants: CFCs → Cl, photochemical (light is required)

• secondary pollutants: none, Cl+O3 → ClO +02 and ClO +O →Cl +O2

• human effects: sunburn (UV-C), skin cancer

• environmental impacts: UV-C light, genetically mutates single-celled organisms (phytoplankton), interference with photosynthesis in plants

• effect an animals: death of eggs, death of phytoplankton, disruption of food chain

CFCs

• non flammable, relatively inert, nontoxic

• used as coolants for refrigeration, in foam for plastics, and industrial solvents

• once in atmosphere, one molecule survives 100 years

• once in the stratosphere (due to atmospheric mixing), CFCs deconstruct under UV light

• destroy ozone molecules

CFC destruction (leading to breakdown of ozone)

• CFC+ UV → Cl

• Cl + O3 → ClO + O2

• ClO + O → Cl + O2

• nowhere in this process did we create O3

• deconstruction weighs down formation

CFCs and Montreal Protocol (1987)

• 1st Cl atom can destroy a lot of ozone molecules which is faster than it can even be created

• banned CFC use in 1987 (US did)

• signed by 150+ countries

• other ozone depleting substances like Methyl Bromide were also banned

Smog

• smoke and fog

London 1952

• the great smog event

• thermal inversion

• mist (water-rich air)

• incomplete combustion of sulfur-rich coal (industry)

• SO2 formed sulfuric acid

• up to 12,000 deaths

reactions are not photochemical

• does not require sunlight to form

• brown smog

• ideal for thermal inversions

• created from transportation

thermal inversions

• cold air mass that gets injected into area of warm air

• deviation from normal increase in temperature as you increase in elevation

• results in cooler layer of air being trapped by a warmer layer

• can occur during warm fronts

• are accentuated due to geography

• causes significant air quality issues by keeping pollution close to the ground

smog and information for it

• source: requires sunlight, transportation, rush hour

• primary pollutants: NOx + VOC

  • VOC: volatile organic compounds

• secondary pollutants: NO2+ UV → NO + O

  • NO + VOC → formaldehyde

  • O+ O2 → O3

• human effects: respiratory issues, O2 is replaced with O3 in lungs

• environmental impacts: decreased photosynthesis because ozone that is exchanged through stomata damaged cells

solutions for SMOG

• catalytic converters

• scrubbers

• baghouse filters

• electrostatic precipitators