chapter 17: atmospheric science and air pollution
TRANSCRIPT
Chapter 17: Atmospheric Science and Air Pollution
Atmosphere
surrounds earth consists of N2, O2, Ar
and others today's altering molecules
consist of CH4, O3, CO2
made up of layers ozone layer
Other Atmospheric Properties
atmospheric pressure– force per unit of area that air exerts on the surface
of Earth– declines with altitude
atmospheric humidity– ratio of water vapor contained in a given volume
of air in relation to it's maximum amount possible– the more humidity the hotter it seems
Seasons
determined by the positioning in relation to the sun atmosphere absorbs 70% of the energy the shorter the distance, the more intense the sun
rays solar radiation intensity is lower at the poles and
higher at the equator tilting of the planet causes the seasons to occur
Air Circulation
known as convective
circulation caused by differences in
humidity and temperature warm air rises as it is less dense cold air descends becoming denser
Weather & Climate
Weather specifies atmospheric conditions over short periods of time and related to relatively small areas
Climate describes patterns of atmospheric conditions across large regions and over long periods of time
Weather
depends on the fronts– cold→ thunderstorms– warm→ light rain
affected by the pressure
systems– high→ fair to dry weather– low→ results in clouds and precipitation
Thermal Inversion
cooler air appears under warmer air prevents normal convective circulation to
occur pollution is trapped under the inversion layer
creating health problems like asthma– killer smog in London– asthma in San Joaquin valley
Global Climate Patterns
Hadley cells: between equator and 30º – heavy rain at the equator– arid at 30º
Global Climate Patterns
Ferrer cells and polar cells lift air creating rain at ~60º
Wind Patterns
caused by the interaction of Hadley and Ferrer cells and Earth's rotation
Coriolis effect: winds are curved
Outdoor Air Pollution
air pollutants– natural sources– human made sources
Natural Pollutants
we have no control, occur naturally– volcano eruptions
Mt. Pinatubo– produces particles– circle the globe and
remain in suspension
for months– acid rain– affect temperature
Natural Pollutants
dust storms
Texas dust storm 1930's Dallas dust storm 2007
Natural Pollutants
Fires– soot and gases– fuel buildup– slash-and-burn
in tropics– El Niño
2000
Gulf Coast
T TX LA
Human Created Outdoor Pollution
primary pollutants– emitted directly to the troposphere– can be harmful to the environment– can form chemicals harmful to the environment
secondary pollutants– react with constituents of the atmosphere
Clean Air Act
1970– set stricter standards for air quality– imposed limits to emissions– funds for pollution control research
1990– strengthen air quality standards– emission trading program for sulphur dioxide– other emission trading programs developed
EPA Standards
carbon monoxide (CO) sulphur dioxide (SO2)
nitrogen dioxide (NO2)
tropospheric ozone (O3) particulate matter lead (Pb)
Carbon Monoxide
colorless odorless incomplete combustion in the U.S. 78% of it comes from vehicles small concentrations can be lethal to most
living organisms
Sulphur Dioxide
colorless pungent odor power plants of coal once in the atmosphere SO2 reacts forming
SO3 and later forming H2SO4
H2SO4 forms acid rain
Nitrogen Oxides
contributes to smog NO2 is foul smelling, redish brown gas
NOx cause acid rain product of combustion engines vehicles produce 50% of the U.S. NOX electricity production and industry the rest
Ozone
product of sunlight + heat + NOX + carbon chemicals
health risk because of its instability→ O2 + Oxygen ion
oxygen ion can cause tissue damage tissue damage can cause respiratory problems
Particulate Matter
particles suspended in air– primary pollutants → dust and soot– secondary pollutants → sulphates and nitrates
can damage respiratory tissues wind-blown result of human activities
Lead
particulate matter enters food chain can cause nervous system malfunction present in gasoline to improve performance
– industrialized nations phased out leaded gasoline
– industrial metal smelting is the problem now
VOCs
volatile organic compounds hydrocarbons
– methane forms part of natural gas– propane used as portable fuel– butane used in portable lighters– octane component of gasoline
Pollutants in the U.S.
2006 137 trillion tons EPA data
Pollution Decreased since 1970
emissions declined 53% since 1970– cleaner burning vehicles– catalytic converter– clean coal technology– baghouse filters– electrostatic precipitators– scrubbers– phase-out of lead in gasoline
Toxic Pollutants
188 toxic pollutants identified by the Clean Air Act in 1990
effects on people– cancer– reproductive defects– neurological problems– developmental problems– affect the immune system– respiratory diseases
Policy: Bush Administration
elimination of new source review of 1977– new pollution targets– retrofitting aging plants with new technologies– industry protested: too costly
Bush Administration exempted older plants allowed installing only "the best available"
technology IF they ever upgraded the plant Clear Skies (stopped by the Senate in 2005)
– from command-and-control to a market-based cap-and-trade
Smog
fogs polluted by smoke= smog– industrial smog– photochemical smog
Industrial smog
gray-air smog coal or oil burning CO, CO2, soot mercury and sulfur in the carbon sample sulfur reacts forming SO2
– sulphuric acid– ammonium sulphate
Problems today: China, India, Eastern Europe
London 1952
Photochemical smog
requires light brown-air smog
– ozone– NOx
– VOCs irritates eyes, nose, throat car inspections reduction of vehicles driven per day
– allow certain cars to drive certain days of the week– promote mass transit
Houston 2000
Problems at Rural Areas
airborne pesticides industrial pollutants from cities, factories and
power plants migrate methane from cattle (18%) feedlots
– CH4, dust, NH4, SOx
can cause respiratory problems
Industrialization
is worsen air quality caused by factories and power plants emissions are released with little effort to control
pollution China & India have 58% of premature deaths
worldwide (WHO) Asian brown cloud
– reduces sunlight– decreases productivity
China
Synthetic Chemicals
CFCs (chlorofluorocarbons) affects the ozone layer creating the ozone hole in Antarctica increases UV radiation leads to more skin cancer ecological effects still unknown hole in the arctic
Arctic hole
Montreal Protocol of 1987
addressed ozone depletion 180 nations agreed to cut CFCs production in
half production and use has dropped by 95% alternative chemicals CFCs take very long to brake down www.epa.gov/cppd
Acid Deposition
– forms of precipitation known as acid rain rain, snow, sleet and hail
– fog– dry particles
originates with the NOx and SOx
pollutants react with water, O2, oxidants produce compounds of low pH (acids) these are suspended in the troposphere before
falling as rain can cause political bickering
Acid Rain
alters soil composition– leaches chemicals from the soil– harming plants and soil organisms– also mobilizes toxic chemicals– converts them to soluble forms– affects agriculture– affect lakes and rivers
causing high mortality in fishes and amphibians
Acid Rain
erosion of buildings corrodes cars erosion of statues and obelisks has not been reduced as expected in 1990 more reduction of sulphur oxides and
nitrogen oxides need to occur
Indoor Air Pollution
higher concentration of pollutants indoor than outdoor
workplaces, schools, homes volatile chemicals in the air
– insecticides– cleaning fluids– plastics– chemically treated wood
Other Sources
wood burning– chimneys– cooking
tobacco smoking radon
Indoor VOC Pollution
perfumes paints plastics oils/candles cleaning fluids adhesives (glues) pesticides and insecticides ink (fax, photocopiers, printers) color films
Living Organisms also Pollute
dust mites animal dander mold bacteria THE END