Air Pollution and Acid Rain

Our Atmosphere Only several miles thick –Supports all life on the planet Roughly 80% N 2, 20% O 2, + CO 2 + Ar, H 2 0 Troposphere – the air we breath Stratosphere – where the ozone layer is

Natural Air Pollution Volcanoes – ash, mercury vapor, H 2 S, etc Trees – hydrocarbons Mentioned in 17 th century by Shakespeare San Gabriel valley in southern California called smoky valley by Native Americans

Smog Smoke + fog –First coined by Dr. Harold deVoeux in London in 1911 Bad case of smog in which 1150 people died –Bad case in Pennsylvania in died and 6000 got sick –In 1900 in SLC, people wrote that usually when they went to work with a white shirt, they would come home with a grey one in the winter

Inversions Trap pollutants and concentrate them Require: –No wind –Warm air over cold –Bowl type area Common along the Wasatch Front Why not here?

Industrial or Reducing Smog Mostly from combustion of coal and oil Major ingredient – SO 2 – along with: –Fly ash –Smoke –Partially oxidized organics Is generally decreasing in the US.

Photochemical or Oxidizing Smog Mainly from the internal combustion engine Major components: –NO –NO 2 –Hydrocarbons –Ozone (O 3 ) Sunlight contributes by producing secondary pollutants

NOx’s N 2 + O 2 + high temperatures → NO –Lightening and auto engines 2NO + O 2 → 2NO 2 With light, (UV), and VOC’s NO 2 → O 3 –VOC’s are Volatile Organic Compounds –So all are interrelated With water → Nitric and Nitrous acids –Source of acid rain Also source of haze

Ozone O 3 – secondary pollutant –Produced from NOx’s Difficult to control Good ozone vs. bad ozone? Big health hazard –Oxidizes the lining in the lungs

Unburned Hydrocarbons Sources? –Urban – gasoline, diesel, charcoal fluid, solvents, and trees –Ephraim? Turkeys and cows and sheep PAH’s – polynuclear aromatic hydrocarbons –Like benzo(α)pyrene –Carcinogens –In coal, cigarette, campfire smoke

Sulfur Dioxide Main component of industrial smog Coal – FeS 2 (Pyrite or fool’s gold) Oil – mercaptans – R-SH Power plants – biggest problem –1000 MW plant – 700 tons of coal/hr Produces 56 tons of SO 2 /hr 1990 Clean Air Act –Cut SO 2 in half by 2000 (-10 mill. Tons/year)

Sulfur Dioxide How do we clean up? –Taller stacks – “the solution to pollution is dilution”

Sulfur Dioxide How do we clean up? –Taller stacks – “the solution to pollution is dilution” –Treat before stacks with lime or sodium carbonate Attacks buildings, plants, and animals Major contributor to acid rain.

Acid Rain Rain is already acidic - CO 2 & NO 2 –pH of normal rain = 5.6 Below 5.6 is acid rain –From SO 2 and NO x ’s Affects: –Lakes – need to be limed –Minerals available to plants –Stomata of leaves –Buildings

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