1. CLIMATE AND TOPOGRAPHY Temperature Inversions Temperature inversions occur when a stable layer of warm air overlays cooler air, reversing the normal temperature decline with increasing height, and preventing convection currents from dispersing pollutants. Subsidence Inversion – large warm air mass moves into a region at a high altitude and floats over a colder air mass near the surface (preventing any vertical mixing) Radiation Temperature Inversion – occurs at night as the air near the ground cools faster than the air above it

2. Inversions

3. ACID DEPOSITION NATURAL ACID CO 2 = carbonic acid (carbon cycle) SO 2 = sulfuric acid (seaspray, volcanoes) NATURAL BUFFER CaCO 3 – calcium carbonate (limestone) TYPES Acid precipitation (rain, sleet, snow) Acid deposition (dry particles washed into soil, aquatic ecosystems) UN-NATURAL ACID SO 2 = Coal burning (sulfuric acid H 2 SO 4 ) NO 2 = Automobiles (Nitric Acid HNO) Carbonic Acid H 2 CO 3 ; Nitric Acid HNO 3 ; Sulfuric Acid H 2 SO 4

4. Acid Deposition

5. Acid Deposition - Impacts Aquatic Effects - acid shock (leaching of acid and Al 3+ ions from soils into water); fish do not live typically below 4.5pH Human Impacts – respiratory (bronchitis, asthma) Damages infrastructure statues, buildings, water pipes (can leach metals into drinking water) Leaches essential nutrients from the soil Damages primary productivity - germinating seeds & plant tissue Wet deposition (rain, snow, fog)/ Dry Deposition (particulates)

6. ACID DEPOSITION CONTROL Wet Scrubbers - Remove SO 2 by injecting limestone – forms calcium sulfate sludge Electrostatic Precipitators - Fly ash particles (smoke & dust) pick up electrostatic charge as they pass between large electrodes in waste stream, and accumulate on collecting plate. Alternative Energy Sources – natural gas, coal low in sulfur content (anthracite); solar; hydroelectric Clean Air Act (1990) – mandated reduction in SO 2 & NO x emissions

7. Clean Air Act (1963) Revision (1990) - Included provision for: Acid Rain Urban Smog Toxic Air Pollutants Ozone Protection Marketing Pollution Rights Volatile Organic Compounds Lead Revision (1997) - Stricter standards