Dr. Largen

• Air Pollution
• Indoor Air Pollution
• Acid Deposition
• Greenhouse Gases & Global Warming

• Acid deposition
• accumulation of potential acid-forming particles on a surface
• acids can result from
• natural causes
• human activities
• combustion
• produces sulfur dioxide and oxides of nitrogen
• converted to sulfuric acid and nitric acid in presence of water and oxidizing agents
• acid-forming reactions classified as
• wet (precipitation)
• reactions occur in atmosphere
• acids come to earth in precipitation
• dry (deposition)
• particles related to acid settle onto a surface
• reactions occur when these materials mix with water
• Acid rain
• collective term used to refer to all acid forming processes
• pH of "normal" rain
• between 5.6 and 5.7
• slightly acidic due to
• formation of carbonic acid when carbon dioxide reacts with atmospheric moisture
• scope of problem
• global
• high acid rain damage
• Canada, England, Germany, France, Scandinavia, US
• can have concentration of acid a thousand times higher than normal
• rain in NH, 1969, pH=2.1 ~ lemon juice
• rain in NE US and Ontario has average pH=4.0-4.5
• Acid rain causes damage to
• human-made materials
• erosion of buildings and monuments made of limestone
• corrosion of metal surfaces
• ecosystems
• terrestrial
• aquatic
• Acid rain causes damage to
• ecosystems
• terrestrial
• forests in NE US
• ~50%mortality of red spruce in some areas
• forests in central Europe
• death of ~14.8 million acres of trees
• link between tree decline and acid rain
• soils become acidic
• aluminum interferes with ability of plant roots to absorb nutrients
• aquatic
• healthy lakes have pH ~6.0
• increase in acidity leads to progressive loss of many kinds of organisms
• experimental acidification of lakes
• pH 5.5, many desirable species of fish are lost
• pH 5, only a few starving fish remained
• pH 4.5, lake was nearly sterile
• scope of problem
• 14,000 lakes in Canada
• 11,000 lakes in US
• Scandinavia
• Acid rain
• extent of damage to ecosystems depends on
• nature of bedrock in area
• soils from igneous rock
• can’t buffer acid rain
• soils from sedimentary rock
• such as limestone
• release bases that neutralize acid rain
• proximity to acid-forming pollution sources
• eastern Canada and NE US
• prevailing west to east winds
• soils have high proportion of granite rock

• Emission of gases to atmosphere
• increasing due to human activities
• activities
• burning fossil fuels
• deforestation
• industrial processes
• gases
• carbon dioxide
• chlorofluorocarbons
• nitrous oxide
• methane
• in 1980s, concern that earth may be getting warmer
• in past 100 years, earth’s
• average temperature has ­ 0.3-0.6 ° C
• sea level has ­ 10-25cm
• 1998 was warmest year on record
• correlation between temperature increase and "greenhouse gases"
• human activity increases amounts of these gases
• Areas of concern related to global warming and climate change
• human health effects
• rising seas levels
• disruption of water cycle
• changing forests and natural areas
• challenges to agriculture and food supply
• what causes global warming?
• several gases in atmosphere
• transparent to light
• allowing sunlight to penetrate atmosphere and be absorbed by earth’s surface
• absorb infrared radiation
• sunlight energy that is absorbed by earth’s surface is re-radiated as infrared radiation
• which is absorbed by gases

Air Quality Issues: Greenhouse Gases & Global Warming

• gases in atmosphere
• allow heat to enter (as sunlight) but retard loss of heat
• producing process called greenhouse effect
• atmospheric gases contributing to effect are called greenhouse gases
• greenhouse gases
• most important are
• carbon dioxide
• chlorofluorocarbons (CFC)
• methane
• nitrous oxide
• Carbon dioxide
• most abundant greenhouse gas
• produced as waste product of
• cellular respiration in living organisms
• energy production
• levels have been increasing for 40 years
• reducing emissions would help slow global warming
• methods to reduce emissions
• increase efficiency of energy usage
• increase amount of carbon dioxide removed from atmosphere
• via photosynthesis which requires it
• Chlorofluorocarbons
• present in atmosphere in minute quantities
• extremely efficient greenhouse gases
• ~15,000 times more efficient at retarding heat loss than is carbon dioxide
• entirely the result of human activity
• refrigerant gases in refrigerators and air conditioners
• cleaning solvents
• propellants in aerosol containers
• expanders in foam products
• in 1970s, CFCs linked to depletion of ozone layer
• located in stratosphere
• absorbs most ultraviolet radiation that is potentially damaging to life
• reactive chlorine is released when CFCs are destroyed after reaching upper atmosphere
• can enter into reactions that deplete ozone
• leading to increase in amount of UV radiation reaching earth
• Methane
• enters atmosphere primarily from biological sources
• released by
• bacteria
• abundant in wetlands and rice fields
• in guts of termites and ruminant animals (such as cattle)
• some enters from fossil fuel sources
• Nitrous oxide
• minor component of greenhouse gases
• enters atmosphere primarily from fossil fuels and fertilizers