Mrs. Sealy APES

VII. Acid Deposition 1. “dilution solution” to air-pollution: to reduce local air pollution and meet government standards without having to add expensive pollution control devices, most coal-burning plants, ore smelters, etc. use taller smokestacks to emit sulfur dioxide high into atmosphere1. “dilution solution” to air-pollution: to reduce local air pollution and meet government standards without having to add expensive pollution control devices, most coal-burning plants, ore smelters, etc. use taller smokestacks to emit sulfur dioxide high into atmosphere 2. increases pollution downwind2. increases pollution downwind

VII. Acid Deposition 3. chemicals reach ground:3. chemicals reach ground: a. Wet: acid rain, snow, fog, cloud vapora. Wet: acid rain, snow, fog, cloud vapor b. Dry:acidic particlesb. Dry:acidic particles c. mixture causes acid deposition (acid rain)c. mixture causes acid deposition (acid rain)

VII. Acid Deposition 4. pH: a numerical measure of the concentration of hydrogen ions in a solution (1 digit change equals 10X change in acidity)4. pH: a numerical measure of the concentration of hydrogen ions in a solution (1 digit change equals 10X change in acidity) a. levels less than 7 - acid (natural precipitation)a. levels less than 7 - acid (natural precipitation) b. levels greater than 7 - Baseb. levels greater than 7 - Base c. typical rain in east USc. typical rain in east US is now about 10 times more acidic (pH 4.3)

Wind Transformation to sulfuric acid (H 2 SO 4 ) and nitric acid (HNO 3 ) Nitric oxide (NO) Acid fog Ocean Sulfur dioxide (SO 2 ) and NO Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Farm Lakes in deep soil high in limestone are buffered Lakes in shallow soil low in limestone become acidic Wet acid deposition (droplets of H 2 SO 4 and HNO 3 dissolved in rain and snow) Fig. 17.9, p. 428

5. What areas are most affected by acid deposition? occurs on a local rather than global basis b/c acidic components only remain in the air for a few daysoccurs on a local rather than global basis b/c acidic components only remain in the air for a few days areas downwind from coal and oil burning power plants, industrial plants and urban areasareas downwind from coal and oil burning power plants, industrial plants and urban areas ecosystems containing acidic soils without natural buffering of basesecosystems containing acidic soils without natural buffering of bases growing problem in China (40% of its land), former Soviet Union, India, Nigeria, Brazil, Venezuela, Columbiagrowing problem in China (40% of its land), former Soviet Union, India, Nigeria, Brazil, Venezuela, Columbia

Potential problem areas because of sensitive soils Potential problem areas because of air pollution: emissions leading to acid deposition Current problem areas (including lakes and rivers) Fig , p. 429

6. What are the effects of acid deposition? medium-risk ecological problem, high-risk to human health medium-risk ecological problem, high-risk to human health human respiratory diseases (bronchitis, asthma), damages statues, buildings, metals, plastics and paints human respiratory diseases (bronchitis, asthma), damages statues, buildings, metals, plastics and paints damages tree foliage, makes trees more susceptible to cold temps, disease, insects, drought, fungidamages tree foliage, makes trees more susceptible to cold temps, disease, insects, drought, fungi harmful to aquatic species harmful to aquatic species

Emissions Effects of Weather Acid deposition Dry weather Low precipitation Increased evapotranspiration Increased transpiration Lake Groundwater SO 2 NO X H2O2H2O2 O3O3 PANsOthers Increased susceptibility to frost, pests, fungi, mosses, and disease Dead leaves or needles Reduced photosynthesis and growth Tree death Damage to tree crown Water deficit Nutrient deficiency Bark damage Direct damage to leaves and needles Leaching of soil nutrients Acids and soil nutrients Damage to fine roots Disturbance of water uptake Disturbance of nutrient uptake Soil acidification Kills certain essential soil microorganisms Release of toxic metal ions Nitrate Sulfate Magnesium Aluminum Calcium Potassium Acids Fig , p. 432

D. What can be done to reduce acid deposition? prevention prevention 1) reducing energy use & thus air-pollution by improving energy efficiency1) reducing energy use & thus air-pollution by improving energy efficiency 2) switching from coal to cleaner-burning natural gas2) switching from coal to cleaner-burning natural gas 3) removing sulfur from coal before it is burned3) removing sulfur from coal before it is burned 4) burning low-sulfur coal4) burning low-sulfur coal 5) removing SO2 particles, particulates, and nitrogen oxides from smokestack gases5) removing SO2 particles, particulates, and nitrogen oxides from smokestack gases 6) removing nitrogen oxides from combustion engines6) removing nitrogen oxides from combustion engines

D. What can be done to reduce acid deposition? reducing coal use is economically & politically difficult reducing coal use is economically & politically difficult clean-up approaches are expensive and mask symptoms w/ out treating causesclean-up approaches are expensive and mask symptoms w/ out treating causes acidified lakes can be neutralized by treating them or the surrounding soil with large amounts of limestone or lime. This is an expensive and temporary remedyacidified lakes can be neutralized by treating them or the surrounding soil with large amounts of limestone or lime. This is an expensive and temporary remedy