Acid Deposition 1
Acid Deposition Brief History Acids and Bases Chemical Processes and Sources Deposition Processes Acid Deposition Distribution Environmental Effects Health Effects Lakes and Forests Abatement 2
Early History of Acid Deposition 1200s: Coal combustion produces SOx and NOx 1750s: Industrial Revolution expands use of coal-fired steam engines Early 1800s: Alkali factories producing compounds for soap release hydrochloric acid (HCl), some sulfuric acid (H2SO4) and NOx 1863 Alkali Act in the UK 3
ph ph: index of acidity or alkalinity of a solution Negative logarithm of the H+ ion concentration Ex. H2SO4 2H + + SO4 2 Difference of 1.0 in ph equivalent to 10x difference in acidity ph = 7.0: neutral ph < 7.0: acidic ph > 7.0: basic 4
Typical ph Values Neutral 1 2 3 4 5 6 7 8 9 10 11 12 13 Vinegar Distilled water Lye Battery acid Cola beverage Natural rain Acid rain Tomato juice Baking soda Ammonia 5
Natural SO2 Sulfur Chemistry SOx SO2 SO3,g Dissolve in liquid water SO3,g + H2O,v Combustion (oxidizes C, S, N) Fossil fuel H2SO4,aq (C + S) Sulfuric acid H2SO4,g/p 6
Natural Sulfur Sources Volcanoes SO2 Organic Decay H2S SO2 7
Anthropogenic Sulfur Fossil Fuels (C + S) 60% Coal 1 6% S Oil 1 2% S Gas 0.5% S 7% Electricity Industrial Other 33% 8
Other Acids NO2 + OH Nitric acid (HNO3) Organic acids Hydrogen chloride (HCl) Anthropogenic: Incineration of PVC plastic Natural: Volcanic emission Methyl chloride (CH3Cl) from ocean 9
Acid Deposition Processes Wet deposition Water coating Acidic gases Washout Rain, snow scavenging Acidic gases Rainout Acidic gases Runoff Cloud or fog droplets 10
Dry deposition Acidic gases 11
ph of Rain H2CO3,aq Unpolluted rain ph ~ 5.6 CO2,g from carbonic acid SOx H2SO4,aq Acid rain ph < 5 from sulfuric acid 12
Regional Transport of Acids Adirondack Mts. SO2 receptor region Local NOx in So. Cal. SO2 source regions SW to NE flow 13
Precipitation ph 14
5.5 6.1 5.5 Precipitation ph Hydrogen ion concentration as ph from measurements made at the Central Analytical Laboratory, 2009 5.3 5.3 6.0 5.7 5.2 5.5 5.8 Sites not pictured: AK01 5.1 AK03 5.1 PR20 5.1 VI01 5.1 5.3 5.6 5.7 5.7 5.5 5.3 6.3 5.8 5.7 5.6 5.6 5.5 National Atmospheric Deposition Program/National Trends Network http://nadp.sws.uiuc.edu 5.2 5.3 5.2 5.3 5.6 5.3 5.6 5.3 5.6 5.7 5.5 5.5 5.5 5.3 5.3 6.0 5.3 5.6 5.5 5.8 5.7 5.9 5.8 6.1 5.9 6.1 6.0 5.3 5.1 5.6 5.2 5.1 5.7 5.2 5.5 4.8 5.1 4.8 4.8 5.5 6.1 5.3 5.1 4.8 4.8 5.2 4.8 4.8 6.0 4.7 4.8 4.8 4.8 5.3 5.1 5.6 4.8 4.7 4.7 5.1 4.6 4.7 4.8 4.7 5.8 5.7 4.8 4.7 4.7 4.8 4.7 5.5 4.7 4.6 4.8 4.8 4.7 4.7 4.7 4.8 4.8 5.6 4.8 5.1 4.8 5.1 4.7 4.8 5.5 5.1 5.1 5.1 5.1 4.8 5.1 4.8 5.1 Lab ph 5.3 5.2-5.3 5.1-5.2-5.1-4.8-4.7-4.8 4.6-4.7 4.5-4.6 4.4-4.5 4.3-4.4 < 4.3 15
SOx Health Effects Effect of SO2 gas on respiratory system (ch. 7) Taste Odor Slight bronchial constriction Inflammation of mucous membranes SO2 + aerosol particles is worse than SO2 alone 16
Freshwater Acidification High-altitude Lakes Low-altitude Lakes Water source = direct precip. and runoff Water source filters through soil buffered Little or no soil buffering East: acidic granite soil West: alkaline limestone soil 17
Freshwater Acidification High-altitude Lakes Low-altitude Lakes Water source = direct precip. and runoff Water source filters through soil buffered Little or no soil buffering East: acidic granite soil West: alkaline limestone soil 18
Effects 19
Effects 20
Effects 21
Effects Aquatic plants and fish are stunted, reproduction impaired Metallic ions (e.g., aluminum, copper, lead) mobilize and leach from soils into nearby lakes 22
Forest Decline Definition: suppression of growth/ reproduction rates and death of trees Susceptible regions: Downwind of sulfur sources Eastern regions of continents, due to west-to-east prevailing winds High elevation Long-term contact with acidified clouds and fog Thinner soils, less buffering Eastern Europe, Northeastern U.S., Southeastern Canada 23
24
Recent Regulatory Action Clean Air Act Amendments of 1970 (US) 1977: National Atmospheric Deposition Program (NADP, US) 1979: Geneva Convention ln Long-range Transboundary Air Pollution 1985: Sulfur Protocol 1988: Nitrogen Oxide Protocol 1994: Second Sulfur Protocol Clean Air Act Amendments of 1990 (US) 25
Abatement Locate acid sources downwind of sensitive areas 26
Abatement Taller stacks Dispersion 27
Abatement Use lowsulfur fuels Oil, gas Low-sulfur coal Coal gassification Solvent-refined coal Scrubbers Reduce emissions Modified combustion 28
Abatement Clean-up Lake and soil buffers 29