Air & Air Pollution

1. Air & Air Pollution

2. See what you know • What is in the air? • What is the difference between Global Warming and Climate Change? • What causes Climate Change? • What are the effects of Climate Change? • What caused the hole in the ozone layer?

3. Whether climate change is occurring or not, isn’t it better to be on the side that believes it is happening? How can changing our ways be a bad thing? Isn’t it better to error on the true side? Human-caused climate change is happening, ..It is happening faster than anyone predicted even a few years ago, and therefore we need to remind ourselves and negotiators need to remind themselves that the longer we delay, the more we will pay, both in terms of lives and in terms of money. - Robert Orr, a top UN official Choosing sides

4. The Atmosphere Greenhouse gasses

5. Atmospheric Gases

6. Atmospheric pressure (millibars) Temperature Pressure Thermosphere Mesopause Mesosphere Heating via ozone Altitude (kilometers) Altitude (miles) Stratopause Stratosphere Tropopause Ozone “layer” Heating from the earth Troposphere Pressure = 1,000 millibars at ground level (Sea level) Temperature (˚C)

7. 1atm = 29.92 Inches of Hg1 atm = 14.696 lb/in2 • Inches of Hg • 1 atm = 29.92 Inches of Hg

8. The Atmosphere in layers Troposphere • Layer in which we live • Most weather occurs here • 90% of the gasses are here • 0-6 mile above N and S Pole • Mount Everest is 5.3 miles tall • 0-10 miles above equator • is made up mostly of nitrogen and oxygen, with smaller amounts of water vapor and CO2 • Stratosphere • 6-10 mile thick • Air traffic due to lack of weather • Ozone layer • Thermosphere • 50 miles to space

9. “Good” Ozone Layer • Ozone (O3) is a gas that occurs both in the Earth's upper atmosphere and at ground level. Ozone can be "good" or "bad" for your health and the environment, depending on its location in the atmosphere. • How much of our atmosphere is ozone? • Ozone that surrounds the earth 12-35 miles above the earth is our first line of defense of the sun’s ultraviolet radiation. UVA, UVB, UVC • This radiation can cause sunburn, skin cancer, cataracts, … • Ozone is constantly created and destroyed

10. Humans need a small amount of ultraviolet radiation to maintain health. Ultraviolet radiation activates vitamin D in the human body, which assists the intestines in absorbing minerals. Humans, as well as other life forms, can tolerate radiation through the UVA range, but radiation with shorter wavelengths, such as UVB and UVC is harmful. Oxygen molecules absorb the shortest and most harmful UVC radiation and ozone absorbs most of the remainder before it reaches the earth’s surface. Ozone, a molecule containing three oxygen atoms, is made when the shortest wavelengths of UVC are absorbed by oxygen and break apart into two oxygen atoms.

11. What Happens to Solar Energy Reaching the Earth? • Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth. Figure 3-8

12. Why is a sunset red? Refraction – of light as it passes through atmosphere and collides with atmospheric gasses. Colors are filtered out and scattered.

14. The Natural Greenhouse Effect • Three major factors shape the earth’s climate: • The sun. • Greenhouse effect that warms the earth’s lower troposphere and surface because of the presence of greenhouse gases. • Oceans store CO2 and heat, evaporate and receive water, move stored heat to other parts of the world. • Natural cooling process through water vapor in the troposphere (heat rises).

15. Major Greenhouse Gases • The major greenhouse gases in the lower atmosphere are water vapor(.04%), carbon dioxide (.0369%), methane(.00018%), and nitrous oxide(.0000315%), ozone (.000005%) • These gases have always been present in the earth’s troposphere in varying concentrations. • Fluctuations in these gases, plus changes in solar output are the major factors causing the changes in tropospheric temperature over the past 400,000 years.

16. Greenhouse Effect • This “greenhouse effect” is vital for our survival. Without heat trapping gasses our planet would be cold and lifeless. • The gasses act like a car that gets hot inside.

17. Albedo - %age of incoming sunlight reflected from a surface

18. Air Pollution – The Big 5 • Air Pollutant is defined as any substance in the air that is concentrated enough to harm living things or to cause damage to man-made objects. • Primary pollutants – released directly into air. • Secondary pollutants – primary pollutants react with other components.

19. Primary Pollutants Secondary Pollutants CO CO2 SO2 NO NO2 SO3 Most hydrocarbons - VOCs HNO3 H3SO4 Most suspended particles H2O2 O3 PANs Most NO3– and SO42– salts Natural Stationary Sources Mobile Fig. 19-3, p. 442

21. Point Source / Nonpoint Source

22. Human Actions and Our Environment • When the human population was low, there was very little impact to the environment. • Wind, rain, and time were the natural air cleaners. • As the human population increased, time could not clean the air fast enough. • Deforestation removes CO2 cleaners.

23. Human Actions and Our Environment • The burning of fossil fuels -- notably coal, oil and gas -- has accounted for about 80 percent of the rise of atmospheric carbon dioxide since the pre-industrial era. Humans have been burning fossil fuel for 400 years adding an enormous unnatural amount of carbon dioxide and other gases in the air. • The human impact has changed three major ecosystem cycles. • The chemical cycles • Carbon Cycle • Nitrogen Cycle • Sulfur Cycle • By adding more chemicals we change the cycle

24. Air Pollution – The Big 5 • Carbon oxides • High levels can suffocate you blood • Put out by automobiles and fires • Unburned Hydrocarbons - VOCs • Combustion of gas • Oil based paint, dry cleaning fluids, petroleum fuels • Methane stores 25 x more energy than CO2. • Nitrogen Oxides • Nitrogen alone is Ok, but at high temps. It reacts with oxygen to form NOx • Makes the sky Brown in smog • Photchemical smog – nitrogen and light form “bad “ozone” • PANs – Peroxyacyl nitrates

25. Air Pollution – The Big 5 • 4. Sulfur Oxides • Naturally occurring • Volcanoes • Burning of coal, oil, gas (cars) • Cause Lung damage, asthma, and bronchitis • Combines with hydrogen to make Sulphuric Acid (ACID RAIN) • 5. Particulates • - PM10 – smaller than 10 um – human hair is about 50-100 um • Small solid particles or liquid droplets in the air • Light enough to float in air • Dust, lead, mercury, radon, ash from fires, road dust, exhaust, wind erosion, • Lung irritant, stain buildings, reduce visibility

26. Major Air Pollutants • Carbon oxides – CO , CO2: • CO2 (10,000 ppm) will make some people feel drowsy. Exhaling into a bag is about 37,000 ppm. • Carbon oxides are highly toxic gasses that form during the incomplete combustion of carbon-containing materials. • 93% of carbon dioxide (CO2) in the troposphere occurs as a result of the carbon cycle. • 7% of CO2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels). • CO2 is a greenhouse gas

28. Major Air Pollutants • Nitrogen oxides and nitric acid: • Nitrogen oxide (NOx) forms when nitrogen and oxygen gas in air react at the high-combustion temperatures in automobile engines and coal-burning plants. NO can also form from lightening and certain soil bacteria. • Photochemical Smog • NO reacts with air to form NO2. • NO2 reacts with water vapor in the air to form nitric acid (HNO3) and nitrate salts (NO3-) which are components of acid deposition.

29. The Nitrogen Cycle:

30. The first thing that starts the chain of events is that people start driving in the morning.  As gasoline is burned, nitrogen (N2) in the atmosphere is also burned, or oxidized, forming nitric oxide (NO) N2 + O2=2NO Hydrocarbons and carbon monoxide (CO) will also be emitted by cars.   Hydrocarbons are volatile organic compounds that may include acetaldehyde, formaldehyde, ethylene, and many other compounds. In the air, nitric oxide combines with molecular oxygen to form nitrogen dioxide within a few hours. 2NO +  O2--------->2NO2 Nitrogen dioxide absorbs light energy and splits to form nitric oxide and atomic oxygen: NO2-->NO + O Then, in sunlight, the atomic oxygen combines with oxygen gas to form ozone (O3): O+ O2--->O3 If no other factors are involved, ozone and nitric oxide then react to form nitrogen dioxide and oxygen gas. O3 + NO<------>NO2 + O2 This last reaction can go in either direction, depending on temperature and the amount of sunlight.  If there is a lot of sunlight, the equation moves to the left, and more ozone is produced.  If nothing else gets in the way, an equilibrium is reached, and the ozone level stabilizes. However, there is something else involved.  Remember that the cars are also emitting hydrocarbons as well as oxides of nitrogen.  Hydrocarbons are the other main ingredient in photochemical smog.  When hydrocarbons are present, nitric oxide reacts with them instead of the ozone. This reaction produces a variety of toxic products, such as a volatile compound known as PAN (peroxyacetyl nitrate). NO + hydrocarbons----------------->PAN and various other compounds.   Also, NO2 +hydrocarbons------------------>PAN and various other compounds

31. Major Air Pollutants • Volatile organic compounds (VOCs): • Most are hydorcarbons emitted by the leaves of many plants. • About two thirds of global methane CH4 emissions comes from human sources. • Other VOCs include industrial solvents such as trichlorethylene (TCE), benzene, and vinyl chloride, hundreds more. • Long-term exposure to benzene can cause cancer, blood disorders, and immune system damage.

32. Methane CH4 • About 25x stronger GHG than CO2. • 1/3rd of methane emissions come from natural sources, mostly plants, wetlands, termites, anaerobic decomposition. • The rest comes from human sources such as rice paddies, landfills, oil and natural gas wells, and cows (from belching or flatulence).

34. Ozone (O3): “bad” ozone - found in troposphere Is a highly reactive gas that is a major component of photochemical smog. It can Cause and aggravate respiratory illness such as asthma Can aggravate heart disease. Damage plants Major Air Pollutants What Causes "Bad" Ozone? Ground-level or "bad" ozone is not emitted directly into the air, but is created by chemical reactions VOC + NOx + Sunlight = Ozone (O3) Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC.

35. Ozone Action Days • Usually occur days that are: • Relatively Hot • Dry • Clear • Little to no wind • Ozone action days can be predicted

36. Major Air Pollutants • Sulfur dioxide (SO2)andsulfuric acid: • About one-third of SO2 in the troposphere occurs naturally through the sulfur cycle. • Two-thirds come from human sources, mostly combustion (S+ O2 SO2) of sulfur-containing coal and from oil refining and smelting of sulfide ores. • SO2 in the atmosphere can be converted to sulfuric acid (H2SO4) and sulfate salts (SO42-) that return to earth as a component of acid deposition.

37. Sulfur in from burning of fuels. • Combustion of gas in automobiles releases sulfur. • Burning of coal releases sulfur. The United States creates a great majority of its electricity by burning coal.

38. The Sulfur Cycle Figure 3-32

39. ACID DEPOSITION • Sulfur dioxides, nitrogen oxides, and particulates can react in the atmosphere to produce acidic chemicals that can travel long distances before returning to the earth’s surface. • Tall smokestacks reduce local air pollution but can increase regional air pollution.

40. Acid Deposition • AKA Acid Rain • Rain cleans the air, but pollutes the water. • Normal rainwater has a pH of 5.6 (slightly acidic). This is because it is exposed to the carbon dioxide in the atmosphere. The carbon dioxide gets dissolved in the rainwater and forms carbonic acid (H{-2}CO{-3}). Acid Rain is anything below 5.6. • Plants like to grown in soil with a pH of 6-7 • What happens to the plants?

41. ACID RAIN Wind Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3) Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts Wet acid depostion (droplets of H2SO4 and HNO3 dissolved in rain and snow) Nitric oxide (NO) Sulfur dioxide (SO2) and NO Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Acid fog Farm Lakes in shallow soil low in limestone become acidic Ocean Lakes in deep soil high in limestone are buffered Fig. 19-6, p. 448

42. ACID DEPOSITION • pH measurements in relation to major coal-burning and industrial plants.

43. ACID DEPOSITION • Air pollution is one of several interacting stresses that can damage, weaken, or kill trees and pollute surface and groundwater.

44. ACID DEPOSITION • Acid deposition contributes to chronic respiratory disease and can leach toxic metals (such as lead and mercury) from soils and rocks into acidic lakes used as sources for drinking water.

45. Solutions Acid Deposition Prevention Cleanup Reduce air pollution by improving energy efficiency Add lime to neutralize acidified lakes Reduce coal use Add phosphate fertilizer to neutralize acidified lakes Increase natural gas use Increase use of renewable energy resources Burn low-sulfur coal Remove SO2 particulates & NOx from smokestack gases Remove NOx from motor vehicular exhaust Tax emissions of SO2 Fig. 19-10, p. 452

46. Major Air Pollutants • Suspended particulate matter (SPM): • Consists of a variety of solid particles and liquid droplets small and light enough to remain suspended in the air. • The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5). • According to the EPA, SPM is responsible for about 60,000 premature deaths a year in the U.S.

47. SPMs • Lead • Mercury • Pollen • Soil • Liquids

48. What is Happening to the "Good" Ozone Layer? Ozone is produced naturally in the stratosphere. But this "good" ozone is gradually being destroyed by man-made chemicals referred to as ozone-depleting substances (ODS), including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, and methyl chloroform. These substances were formerly used and sometimes still are used in coolants, foaming agents, fire extinguishers, solvents, pesticides, and aerosol propellants (propane).

49. Atmospheric pressure (millibars) Temperature Pressure Thermosphere Mesopause Heating via ozone Mesosphere Altitude (kilometers) Altitude (miles) Stratopause Stratosphere Tropopause Ozone “layer” Heating from the earth Troposphere Pressure = 1,000 millibars at ground level (Sea level) Temperature (˚C) Fig. 19-2, p. 440

50. Ozone • CFC – Chlorofluorocarbons react with an oxygen atom to break down O3 to O2. • 1 chlorine can destroy 100,000 ozone molecules • As ozone is broken down, the ozone layer gets thinner. • This radiation that gets through can cause sunburn, skin cancer, cataracts, …