Chapter 6 (CIC) Read in CTCS Problems in CTCS:

Acid Rain Natural rain is at pH = 5.6 CO 2 + H 2 O H + + HCO 3 - Acid is clearly in Eastern 1 / 3 of US (Ohio River Valley) Must be due to more than just CO 2 SO 2, SO 3, NO, NO 2 (SO x and NO x ) SO x is primarily from coal fired power plants, steel mills and heavy industry NO x is found in large urban areas with heavy population densities – auto traffic

Where’s the H + ? Just like with CO 2, SO x and NO x are acid anhydrides But where did the S come from in coal? –C 135 H 96 O 9 NS –Ca, Si, Na, Al, Ni, Cu, Zn, As, Pb, Hg can also be found in ash –amino acid cysteine

Statistics US is about 50:50 in NO x and SO x 86% of SO 2 is from coal fired electrical utilities 46% of NO x is from coal fired electrical utilities Twice as much SO x as NO x worldwide Difficulties in getting global air treaty (Kyoto) USChina million tons10 million tons million tons

Source (Worldwide)SO 2 NO x Natural (in millions of metric tons/yr) Oceans221 Soil and Plants243 Volcanoes19 Lightning15 Subtotals4359 Anthropogenic Fossil Fuels Combustion14255 Industry-ore smelting13 Biomass Burning530 Subtotals16085 Totals203144

What does Acid Rain Do? Marble statues (Parthenon-Greece; Taj Mahal- India; Mayan ruins-Mexico; US Capitol; Stalagtites in Lincoln Memorial) Rusting of Steel (bridges, buildings, railroads) –Coat metal with Zn or Cr Visibility Illness in elderly, asthma, bronchitis, and emphysema –EPA estimates saving $12-40 billion in health care because of 90’ Clean Air Act Solubility of toxic metals (Pb, Cd, Hg)

Great Smoky Mountain National Park… …on a hazy day Visibility

Damage to Lakes and Streams Healthy lakes have a pH of no less than 6.5 A pH below 5.0 has few species surviving A pH below 4.0 is essentially dead CaCO3 buffers a lake H+ can release Al3+ - mess up gills Add lime, Ca(OH)2, to lakes

Trees and Forests 1993 – 25% of all European trees had lost 25% or more of their needles Acid tends to make the trees more susceptible to: –Insects –Disease –Weather –drought

Costs 1990 Clean Air Act –Phase I – Reduce power plant SO 2 emissions by 10 million tons below 1980 levels for 110 of 2000 dirtiest plants (from 10lbs/10 6 BTU to 2.5 lbs/10 6 BTU) –2 million ton reduction of NO x Starts in 1995 –Phase II – Reduce SO 2 to 1.2 lbs/10 6 BTU –Includes other power plants Starts in 2000

Options 1. Move to clean coal (little S) –It’s nearly all gone in the east; transport from the west 2. Clean up coal to remove S –$750/ton SO 2 3. Neutralize SO 2 by scrubbing –$500/ton SO 2 mostly for disposal of CaSO 4 –SO 2 + O 2 + CaCO 3  CaSO 4 + CO 2 59% have chosen option #1 (get less energy/g coal) 28% have chosen option #3

Estimated Costs Congressional Office of Technology Assessment: $3-4 billion per year Electric Power Companies: $4-23 billion/yr Actual Costs $836 million in $3/person in the US Utility bills have remained nearly constant over the last decade