AICE Environmental Management Final Exam Review - Unit#7 Managing the Atmosphere

7.1 Acid Deposition

  • Definition: Acid deposition is a mix of pollutants depositing as acidic wet (pH < 5.6) or dry deposition.

  • Primary Pollutants: Directly from sources (e.g., sulfur dioxide from coal burning).

  • Secondary Pollutants: Formed when primary pollutants react chemically (e.g., smog, sulfuric acid).

Wet vs. Dry Deposition

  • Wet Deposition: Includes snow, rain, and fog; secondary pollutants like sulfuric and nitric acids fall far from their source.

  • Dry Deposition: Includes dust and gases; primary pollutants like sulfur dioxide and nitrogen oxide fall close to their source.

Formation Steps

  • Sulfur dioxide + water + oxygen → sulfuric acid

  • Nitrogen monoxide + oxygen + water → nitric acid

Impacts of Acid Deposition

  • Aquatic Life: Kills larvae of fish and mollusks, affects fish gills.

  • Vegetation: Damages chloroplasts, reduces crop yield, defoliation of trees.

  • Buildings: Erodes stone structures, corrodes cars, impacts roads.

Acid Deposition Prevention Strategies

  • Use renewable energy sources (wind, solar, geothermal, hydropower)

  • Increase public transportation

  • Legislation (Clean Air Act 1990)

  • Industrial smoke stalks should have scrubbers: chemically convert/remove pollutant before they leave the smoke stalk

  • Cars having catalytic converters

  • Clean coal technologies

7.2 Photochemical Smog

  • Definition: A mixture of pollutants formed by the reaction of NOx and VOCs in sunlight; includes ground level ozone.

  • Sources: Car exhaust, vegetation, paints, gas stations.

  • Chemical Equation: NOx + VOC’s + UV Ray’s ——> Photochemical Smog (O3)

Impacts of Photochemical Smog

  • Causes eye and respiratory irritation

  • Lung damage/cancer

  • Asthma attacks due to allergens

  • Decreased crop yields

  • Deterioration of plastics and rubber

  • Reduce visibility (affects transportation)

7.3 Managing Air Pollution

Strategies to Reduce Pollution

  • Use renewable energy (wind, solar).

  • Increase public transportation use.

  • Improve vehicle emissions through catalytic converters.

  • Legislation (e.g., Clean Air Act, Polluter Pay Principle).

Specific Reductions

  • Sulfur dioxide: flue gas desulfurization.

  • Oxides of nitrogen: catalytic converters.

  • Particulates: electrostatic precipitators.

  • VOCs: safe usage and disposal of products.

7.4 Ozone Depletion

  • Measurement: Ozone concentrations measured in Dobson Units; <100 DU indicates an ozone hole.

  • Causes: Synthetic chemicals (CFCs) disrupt ozone, emitted from aerosols and refrigerants.

Steps in Ozone Depletion

  1. CFCs are stable, reaching the stratosphere.

  2. UV light breaks down CFCs, releasing chlorine.

  3. Chlorine reacts with ozone (O3) to produce oxygen (O2).

Impacts of Ozone Depletion

  • Human Health: Increased eye cataracts, skin cancer.

  • Agriculture: Reduced crop yield.

  • Biodiversity: Damage to chloroplasts reduces plant productivity.

Specific Conditions Over Antarctica

  • Polar stratospheric clouds form in cold temperatures, trapping chlorine and enhancing depletion.

  • Once it gets warm the clouds deplete quickly, depleting the ozone

Alternatives to Ozone Depleting Substances

  • HCFCs: Less harmful, shorter life spans compared to CFCs; useful in refrigeration, produce less ozone depletion.

  • F-gases: Potent greenhouse gases, significantly impact global warming.

International Agreements

  • Vienna Convention: Promotes cooperation for ozone layer protection.

  • Montreal Protocol: Phases out ozone-depleting chemicals.

Rowland-Molina Hypothesis

  • CFCs are responsible for ozone depletion; initially doubted, confirmed through further research.