chap 12
greenhouse gases
(water vapor, carbon dioxide, methane, and nitrous oxide) allow mostly visible light and some infrared radiation and UV radiation from the sun to pass though the atmosphere. The earth's surface absorbs much of this solar energy and transforms it to longer-wavelength infrared radiation (heat), which then rises into he troposphere.
Six primary pollutants
1) Carbon monoxide 2) Hydrocarbons 3) Particulate matter (2.5 um and 10 um) 4) Sulfur dioxide 5) nitrogen oxides 6) Led *Carbon dioxide **an additional 188* substances are regulated under the U.S. Clean Air Act, section 12 (HAPS)
how air circulates in lower atmosphere
1) uneven heating of the earth's surface by the sun 2) rotation of the earth on its axis 3) properties of air, water, and land.
Air pollution is a big killer
3.2 million deaths per year worldwide (mostly Asia)
Mercury risk and dose
5.8 parts per billion (ppb) Hg in mother doubles risk of poor results in neurodevelopment tests in child No safe level down to at least 1 ppb Hg 1 in 2 women (16-49 yrs) in US has >1 ppb Hg EPA "reference dose" 5.8 ppb; "some risk" 1 in 12 women (16-49 yrs) has >5.8 ppb
troposphere
75-80% of earth's air mass is found here as it is the closest spherical to earth's surface. Only extends 17 km or 11 miles above sea level at the equator and 6 km or 4 miles over the poles.
air
99% of air inhaled consists of 78% nitrogen and 21% oxygen.
What is acid depositions and why is it a problem?
Acid deposition is mainly caused by coal-burning power plants and motor vehicle emissions, and in some regions it threatens humann health, aquatic life and ecosystems, forests, and human-built structures.
Ozone and CFCs (freon) each molecule of a CFC can last 65-385 years
CFCs "freon" used widely as refrigerants, foam, solvents, propellants beginning in 1960 Cheap, non-reactive, nontoxic; $28 B/yr for DuPont! Invented (discovered?)1928 by Thomas Midgley, Jr. (also gave us leaded gasoline)
Risk of particulates
Can accumulate in lungs and interfere with the ability of lungs to exchange gases. Some particulates are known carcinogens Those working in dusty conditions at highest risk (e.g., miners) pollution decreased 88% from 1970 - 2000 ("big" particles are easy to see & thus easy to regulate)
effects of acid rain
Can acidify freshwater lakes (pH<4.7) Disrupt physiological processes Release of toxic compounds normally bound to soil (e.g. aluminum) Inhibition of nitrification, build up of ammonia Causes loss of game fish & other desirable species 25,000 lakes in N. America altered by acidification Midwest lakes often on limestone, which neutralizes acids
Clean Air Act 1970, 1977, 1990
Control requirements the federal government implements and states administer
why should we worry about ozone depletion?
Damaging UV-A and UV-B radiation Worse sunburns, more eye cataracts, and more skin cancer Impairs or destroys terrestrial and aquatic organisms (esp. phytoplankton) Loss of ecological services
Control of Air pollution
Different Approaches Regulations on auto industry Fines to enforce bans Switch from high sulfur coal to low sulfur coal Switch to oil, gas, wind, solar, nuclear power "Scrubbers" on smoke stacks to remove sulfur after use expensive -- $200 million per power plant Much of regulation done under Clean Air Act
Indoor air pollution
In U.S., 90% of time spent indoors; inside air often more polluted than outside air Problems with weatherized building: little air exchange Asbestos, carbon monoxide, formaldehyde, lead, pollen, dust, smoking Causes diseases: emphysema, heart attacks, strokes, lung cancers
Mercury Poisoning (uncertainty at low doses)
In poisonous form—methyl mercury—damages neuro-behaviors (attention, fine motor skills, language, drawing, memory) and cardiovascular, immune, and reproductive systems Greatest risk prenatal, childhood Pathway: burning coallong-distance air transportin waters, bacterial conversion to methylmercuryfishhumans (motherfetus) In poisonous form—methyl mercury—damages neuro-behaviors (attention, fine motor skills, language, drawing, memory) and cardiovascular, immune, and reproductive systems Greatest risk prenatal, childhood Pathway: burning coallong-distance air transportin waters, bacterial conversion to methylmercuryfishhumans (motherfetus)
Primary air pollutants
Materials that when released pose health risks in their unmodified forms
more CFCs story
National Academy of Science confirms the theory, 1976 "Nonessential uses" (spray cans) eliminated, 1978 Further regulation fought by "Alliance for Responsible CFC Policy"—industry front group—and Reagan's EPA Administrator Ann Gorsuch. New NAS report downplayed threat, 1984. Discovery of South Pole ozone "hole", 1984 The role of satellite telemetry... Vienna Convention to limit CFCs; toothless, 1985. Hole increasing yearly. Industry develops profitable alternatives Montreal Protocol to phase out CFCs, 1987 Thatcher changes heart, supports CFC ban the first global environmental agreement Copenhagen Protocol, stricter, 1992 Nobel Prize to Rowland and Molina, 1995 What was the cost of delaying? Several million cases of skin cancers and a centuries-long recovery
Sherwood Rowland and Mario Molina
Nature, 1974. CFCs exposed to UV release chlorine which catalyzes ozone destruction Rowland tells wife "The work is going very well. It looks like the end of the world."
ozone depletion
Our use of certain chemicals threatens the ozone layer Ozone thinning Seasonal depletion in the stratosphere Antarctica and Arctic Ozone-depleting chemicals Chlorofluorocarbons (CFCs), halons, methyl bromide, hydrobromoflurocarbons (HBFCs), hydrogen chloride, and cleaning solvents
What are the major outdoor air pollution problems?
Pollutants mix in the air to form industrial smog, primarily as a result of burning coal and photochemical smog, cause by emission from motor vehicles, industrial facilities, and power plants.
Dealing with Air Pollution
Pollution control to prevent release Remediation to clean up and restore Resource conservation including recycling and reuse Ecosystem conservation for wildlife and human habitat preservation Commitment to end extreme poverty and support sustainable economies and food Support technology transfer from developed to developing world to prevent pollution Support sustainable economic systems without destroying the environment Support public transportation initiatives
Secondary air pollutants
Primary pollutants interact with one another, sunlight, or natural gases to produce harmful, new compounds
Carbon Monoxide
Produced by burning organic material (gas, coal, trash,) Autos biggest producer and cigeratte smoke is another. On the road mobile 51% Nonroad 26%, other not mobile 23%
Sulfur Dioxide
Produced by burning sulfur containing fossil fuels (coal, oil) Coal-burning power plants major source Reacts in atmosphere to produce acids One of the major components of acid rain
Nitrogen Oxides
Produced from burning of fossil fuels Contributes to acid rain, smog Automobile engine main source New engine technology has helped reduce pollution, but this reduction has been offset by an increase in the number of cars and thus there is more pollution!
US Sources of Sulfur and nitrogen oxide
SO=66% of electic utlities 5% vechiles NO=58% vechiles, 18% electric utilities
Stratosphere
Second layer (above troposphere) which extends from about 17-48 km or 11-30 miles above the earth's surface. Contains less matter than troposphere, its composition is very similiar, with two notable differences: its volume of water vapor is about 1/1000 that of the troposphere, and its concentration of ozone is much higher.
Since clean air act
Since Clean Air Act passage, EPA reports air pollution cut by 1/3 and acid rain cut by 25%. EPA estimates human health, welfare, and environmental benefits have outweighed costs by 40 to 1. Old coal-fired power plants and SUVs, diesel trucks and buses are still major problems
We Can Reverse Stratospheric Ozone Depletion
Stop making all ozone-depleting chemicals Would require 60-100 years for significant ozone recovery 1987: Montreal Protocol Reduce CSC emissions 1992: Copenhagen Protocol Phase out ozone-depleting chemicals Ozone protocols: prevention is the key
Acid rain
Sulfur dioxides and Nitrogen oxides combine with water in the atmosphere to form sulfuric acid and nitric acid The pollutants remain airborne for ~1-3 days and travel 250-750 miles Combine with water in the atmosphere, fall back as rain, snow, etc. - water with pH more acidic than normal rainfall. US and Canadian governments officially recognized effects in 1986
Clean Air Interstate Rule
The U.S. EPA finalized the 2005 Clean Air Interstate Rule caps emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) in the eastern United States.
Threshold myth
The idea that "the dose makes the poison" is a myth In fact, years of "non-killing exposure" can damage respiratory system, and increase vulnerability Mortality, disease patterns revealing relationship to airborne toxins Story of lead in gasoline Marketing neurotoxin tetraethyl lead as "Ethyl" as an "anti-knock" additive 7 million tons burned in gasoline, 1920s-90s
what are the major indoor pollution problems?
The most threatening indoor air pollutants are smoke and soot from wood and coal fires (mostly in less-developed countries), cigarette smoke, and chemicals used in building materials and products.
Facts on Sulfur Dioxide
When inhaled, SO2 can be very corrosive to lung tissue Also damages metal, stone and other building materials A little bit of history As early as 1306, the burning of soft coal was banned in London... In 1952, "killer fog": killed 4,000 people in 4 weeks This event got peoples attention and some of the earliest pollution laws were passed...
How might the earth's temperature and climate change in the future?
a. Evidence indicates that the earths' atmosphere is warming because of a combination of natural effect and human activities, and that this warming is likely to lead to significant climate change during this century. b. the projected rapid change in the atmosphere's temperature could have severe and long-lasting consequences, including increased drought and flooding, rising sea levels, and shifts in the locations of croplands and wildlife habitats.
How have we depleted the ozone in the stratospher and what can we do about it?
a. Our widespread use of certain chemicals has reduced ozone levels in the stratosphere, which allows more harmful ultraviolet radiation to reach the earth's surface. b. To reverse ozone depletion, we must stop producing ozone-depleting chemicals and adhere to the international treaties that ban such chemicals.
Transboundary problem
airborn particles mix, dilute, but remaind in atmosphere, accumulating in direction of winds
Hazardous Air Pollutants (HAPS)
compounds that can harm human health or damage the environment. Some released from consumer activities. Benzene escapes during automobile refilling. Most released from manufacturing Toxic chemicals released from smelters Chemical and petroleum industry are primary sources
Ozone layer
concentrated in statosphere, found 17-30 km above sea level. Ozone produced in the stratosphere is when some of the oxygen molecules there interact with the ultraviolet radiation emitted by the sun. Keeps 95% of UV from reaching the surface.
six giant convention cells
distribute heat and moisture over the earth's surface.
Antartica Ozone hole
during October and November
climate
general pattern of atmospheric or weather conditions over long periods of time ranging from at least three decades to thousands of years. Average temperature and average precipitation are two main factors determinings climate along with latitude and altitiude
lead poison
highly toxic pollunatnt
weather
is short-term atmospheric conditions, which include temperature, precipitation, humidity, wind speed, cloud cover, and other factors.
Hydrocarbons
organic compounds with hydrogen, carbon From incomplete burning or evaporated from fuel supplies Major source is automobiles, but some from industry Contribute to smog Improvements in engine design have helped reduce Other not mobile sources 53% Nonroad mobile 18% Onroad mobile 29%
air pollution
prescense of chemicals in the atmospher in concentrations high enough to harm organisms, ecosystems, or human-made materials, or to alter climate
ocean currents
redistribute heat around the planet, thereby influencing climate and vegetation, especially near coastal areas.
Photochemical smog
secondary pollutants formed by reaction of nitrogen oxides and HC with sunlight Includes ozone (O3) destroys chlorophyll, injures lung tissue ground-level ozone is "bad ozone" Biggest problems in cities, mountains can make it even worse Mountain ranges, wind directions lead to thermal inversions when cool air is trapped below layer of warm air pollutants accumulate, aren't released to upper atmosphere
Particulates
small pieces of solid materials and liquid droplets (2.5 mm and 10 mm) Examples: ash from fires, asbestos from brakes and insulation, dust Easily noticed: e.g. smokestacks More attention, more regulation
What is the nature of atmosphere?
the two innermost layers of he atmosphere are the troposphere (which supports life) and the stratosphere (which contains the protective ozone layer).
atmosphere
thin blanket of gases that is divided into several spherical layers: thermosphere, mesosphere, stratosphere, and troposphere.
SPM (suspended patriculate matter)
tiny particles of solids or droplets of liquieds suspended in the air
industrial smog
unhealthy mix of sulfur dioxide, suspended droplets of sulfuric acids and a variety of suspended solid particles.0
How should we deal with air pollution?
we can use legal, economic, and technological tools to try to clean up air pollution, but the best solution is to prevent it.
temperature inversions
weather events in which a layer of warm air temporarily lies atop a layer of cooler air nearer the ground, prevention the natural rising an mixing of air form the ground to higher lever.s
