Class 16 - 3/2/11 Visibility Acid Rain GEOG 371...

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Unformatted text preview: 3/2/11 Visibility Acid Rain GEOG 371 March 3, 2011 Visibility Defini-ons Meteorological range Distance from an ideal dark object at which the object has a 0.02 liminal contrast raFo against a white background Liminal contrast raFo Lowest visually percepFble brightness contrast a person can see Visual range Actual distance at which a person can discern an ideal dark object against the horizon sky Prevailing visibility Greatest visual range a person can see along 50 percent or more of the horizon circle (360o), but not necessarily in conFnuous sectors around the circle. 1 3/2/11 Visibility The intensity of radiaFon increases from 0 at point x0 to I at point x due to the scaRering of background light into the viewer’s path Figure 7.21 Meteorological Range (7.9) Change in object intensity along path of radiaFon dI = σt (I B − I ) dx (7.10) Total exFncFon coefficient σ t = σ a,g + σs, g + σa, p + σs, p Integrate (7.9) (7.11) IB − I −σ x =e t IB Define liminal contrast raFo  ­ ­> meteorological range I −I Cratio = B = 0. 02 IB → (7.12) x= 3.912 σt 2 3/2/11 Meteorological Range Meteorological Range (km) Gas Gas Particle Particle scattering absorption scattering absorption All Polluted day 366 130 9.59 49.7 7.42 Lesspolluted day 352 326 151 421 67.1 (Larson et al., 1984) Table 7.4 Winter and Summer Maps of Light Ex-nc-on Schichtel et al. (2001) 3 3/2/11 Color of Pollutants Nitrogen Dioxide is Brown •  From preferenFal absorp)on of blue and some green and transmission of red and remaining green (which makes brown) Soot is Black •  Soot appears black because it absorbs all visible wavelengths (blue, green, red) and transmits no light. Infrared Infrared Los Angeles Haze Gene Daniels, U.S. EPA, May, 1972, SFll Pictures Branch, U.S. NaFonal Archives 4 3/2/11 Haze and Fog Over Los Angeles Gene Daniels, U.S. EPA, May, 1972, SFll Pictures Branch, U.S. NaFonal Archives Colors in Los Angeles Smog (Dec. 2000) Mark Z. Jacobson 5 3/2/11 Red Sky Due to Smog (Salton Sea, California) Charles O'Rear, U.S. EPA, May, 1972, SFll Pictures Branch, U.S. NaFonal Archives Purple Sky ARer El Chichon Volcano, 1982 J. Lew 6 3/2/11 Visibility Monitoring •  hRp:// Projects/AirVisibilityMonitoring • hRp:// •  hRp:// hRp:// ACID RAIN 7 3/2/11 PrecipitaFon •  The GOOD: –  washes pollutant parFcles from the air –  helps to minimize parFculate maRer formed by acFviFes such as construcFon and some industrial processes. •  The BAD: –  Acid Rain 15 History of Acid Deposi-on 1200s. Coal used in lime kilns and forges produced sulfur dioxide that resulted in sulfuric acid deposiFon. 1750s. Expanded use of the steam engine at the beginning of the Industrial RevoluFon increased sulfuric acid deposiFon. 1781. French Academy of Sciences offered a prize to a person who finds the most efficient and economical method to produce soda ash Na2CO3(aq), which along with animal fat, is an ingredient in soap. 1789. Nicolas LeBlanc comes up with a two ­step process. 8 3/2/11 History of Acid Deposi-on 1791. LeBlanc patented technique 1793. Lost patent to the state during French RevoluFon 1806. LeBlanc commits suicide 1838. Liverpool landowner files complaint against an alkali factory: destroyed crops and interfered with hunFng. Early 1860s. William Gossage, who built alkali factory in 1830, developed scrubber for HCl(g) by converFng a windmill into a tower, filling tower with brushwood, and lelng water drip down the brush as smoke rose from the boRom. History of Acid Deposi-on 1861. Ernst Solvay (1838 ­1922) developed another way to form soda ash, but it took unFl 1880s to replace Leblanc process. 1863. Due to devastaFon from Alkali factories and Gossage’s scrubber, the 1863 Alkali Act passed in the U.K. France. RegulaFon took the form of planning laws controlling locaFon of alkali factories. 1866, 1868. InvenFons allowed chlorine to be recycled for bleaching powder. 1881. U.K. Alkali Act modified since sFll significant polluFon of other chemicals from alkali factories. 9 3/2/11 Recent History •  1970’s: observaFons of increased acidity in lakes and streams is linked to long range transport of pollutants •  1980: Acid DeposiFon Act established a 10 year research program (NAPAP: NaFonal Acidic PrecipitaFon Assessment Program) •  1990: amendments to the Clean Air Act are designed to control SO2 and NOxemissions 19 Recent Regula-on of Acid Deposi-on 1970. U.S. Clean Air Act Amendments 1977. U.S. NaFonal Atmospheric DeposiFon Program 1979. Geneva ConvenFon on Long ­Range Transboundary Air PolluFon 1985. Sulfur Protocol 1988. Nitrogen Oxide Protocol 1990. U.S. Clean Air Act Amendments 10 3/2/11 The pH scale •  “clean rain” has a pH of 5.6 •  “Acid rain” is anything with a pH <5 Source: “Acid Rain Revisited” Hubbard Brook Research FoundaFon 21 22 11 3/2/11 Chemistry of Acid Rain Source: hRp:// 23 What are the effects? •  Global circulaFon makes acid rain a global problem. •  All parts of the ecosystem are effected directly or through secondary effects –  Soil •  Loss of calcium •  Build of up sulfur and nitrogen –  Forest stress •  Decreased tolerance for cold •  Root funcFon and nutriFon mechanisms are impaired –  Water •  Acidified lakes and streams effect the whole ecosystem •  AquaFc life is threatened, loss of species, etc. 24 12 3/2/11 Acidified Forest, Oberwiesenthal, Germany (1991) Stefan Rosengren/Naturbild Acidified forest near Most, Czechoslovakia (1987) Owen Bricker, United States Geological Survey 13 3/2/11 What are the effects? •  People –  Health effects from SO2 and NOx •  Infrastructure (cars and buildings) 27 Effects of Acid Deposi-on Materials The addiFon of sulfuric acid to marble or limestone produces gypsum, which forms a crust that creates pits when rain loosens the crust. CrusFng of marble and limestone CaCO3(s) + 2H+ Calcium Hydrogen carbonate i on Ca2+ + CO2(g) + H2O(aq) Calcium Carbon Liquid i on dioxide water gas 2+ + SO 2- + 2H O(aq) CaSO4-2H2O(s) Ca 4 2 Calcium Sulfate Liquid Calcium sulfate ion ion water dihydrate (gypsum) (10.17)  ­ (10.18) 14 3/2/11 Cathedral of Learning, PiZsburgh, 1930 and 1934 University Archives, University of PiRsburgh Sandstone Figure in 1908 and 1968, Westphalia, Germany Herr Schmidt ­Thomsen 15 3/2/11 Effects •  In 1991, NAPAP provided its first assessment of acid rain in the United States. –  5% of New England Lakes were acidic –  2% of the lakes could no longer support Brook Trout –  6% of the lakes were unsuitable for the survival of many species of minnow •  Subsequent Reports: –  chemical changes in soil and freshwater ecosystems, nitrogen saturaFon, decreases in amounts of nutrients in soil, episodic acidificaFon, regional haze, and damage to historical monuments. 31 Monitoring Networks •  NADP: NaFonal Atmospheric DeposiFon Program (1977) –  Weekly monitoring at 250 staFons –  Long term data records available to the public –  hRp:// 32 16 3/2/11 Measured DeposiFon •  •  •  •  •  •  Hydrogen (acidity as pH) Sulfate Nitrate Ammonium Chloride Base caFons –  calcium, magnesium, potassium and sodium •  (Mercury) 33 The NADP Network 34 17 3/2/11 Sulfate Ion Wet Deposi-on 1985 ­2005 1984 1985 1986 35 Control/PrevenFon •  Emissions control •  SO2 –  Different fuel –  Scrubbing to remove before emission •  NOx –  changing the raFo of air to fuel –  changing the temperature of the combusFon 57 18 ...
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This note was uploaded on 06/16/2011 for the course GEOG 371 taught by Professor Hiscox during the Spring '11 term at South Carolina.

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