Download 20.1 Atmosphere and Weather I

20.1 Atmosphere and Weather
I-Atmospheric Structure
A- Troposphere-Lowest level
a. Ranges in thickness from 10 miles in the tropics to five miles in higher altitudes
b. Moderates flow of energy to the earth
c. Contains practically all water vapor and clouds in the atmosphere.
d. Source and site of all of our weather
e. Gets colder with altitude, except for local temperature inversions
f. Vertically well mixed air masses so pollutants can reach top
g. Substances entering toposhere can be chemically changed and washed back to Earth in
precipitation
B-Tropopause- layer that separates troposphere and Stratosphere.
B- Stratospherea. Temperature increases with altitude because of ozone which absorbs high energy
radiation emitted by sun.
b. Not well mixed vertically, and no precipitation so substances remain for a long time
II-Weather- Day to day variation
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Climate- long term weather patterns in a region
Atmosphere- ocean- land system is enormous weather engine fueled by sun and
affected by earth’s rotation and tilted axis.
 Solar radiation can be reflected by clouds and earth’s surface, but most absorbed by
atmosphere, oceans and land.
 Land and and oceans radiate some of the heat back upward as infrared energy
A- Flowing Air
a. Some air transferred back into atmosphere from oceans and land cause airmasses to
grow warmer at earth’s surface and tend to expand becoming lighter.
b. Lighter air then rises and creates vertical air currents.
c. Air flows down to replace the air that rose and creates horizontal airflows, a.k.a wind.
d. Horizontal air flow source is cooler air that is sinking.
B- Convection Currents- bring day-to-day changes in weather as they move from east to west.
a. Rising air creates high pressure up in atmosphere, which leaves low pressure area closer
to earth.
b. Once moist , high pressure air has cooled by radiating heat to space and by
condensation( which causes precipitation), the air then flows horizontally towards
regions of sinking cool air, dry air(where pressure is lower). Then air is warmed and
creates region of high pressure.
i. Differences in pressure lead to airflows, which causes the wind we experience.
ii. Winds tend to flow from high pressure to low pressure regions.
C- Jet streams- caused by earth’s rotation and air pressure gradients, veritable rivets of air that flow
eastward at over 300mph and meander considerably.
a.
Larger scale air movements of Hadley Cells are influenced by Earth’s rotation from west
to east. This creates tradewinds over oceans and general flow of weather from west to
east.
b. Jet streams steer major air masses in lower troposphere. I.e- Polar jet stream which
steers cold air masses into North America.
D- Put together..
a. Fronts- air masses of different temperatures meet at this boundary, regions of rapid
weather change.
b. Hurricanes, typhoons, and tornadoes- other movements of air masses due to differences
in pressure and temperature.
c. Monsoons- seasonal airflow example. Represents reversal of previous wind patterns.
Created by major differences in cooling and heating between oceans and continents.
d. Putting everything together- general atmospheric circulation patterns and the resulting
rain + wind and weather systems that generate those + rotation of Earth and tilt of the
planet on its axis, which creates the seasons= general patterns of weather that
characterize different regions of the world, these patterns known as climate.
Climate 20.2
The average temperature and precipitation expected throughout a typical year in a given region
A major change in climate is a major threat to the structure and function of the existing ecosystems
In the Past
Global average temperature, since 1855, has shown periods of warming and cooling. (We have been
in a warming period since 1976)
**It has increased 0.6°C (1°F)**
Proxies- measurable records that can provide data on temperature, ice cover and precipitation.
Examples: tree rings, pollen deposits, changes in landscape, marine sediments, corals, and ice
cores
Isotopes- alternative chemical configurations of a given compound
Ocean and Atmosphere
Milankovitch Cycles- 100,000; 41,000; 23,000 years
After the last ice age the Earth’s avg. temperature rose 7°C in just 50 years (possibly by the link
between the atmosphere and oceans)
**The Earth is covered more than 2/3 by oceans**
The oceans are the major source of heat entering the atmosphere, partially because of their heat
capacity and conveying heat through the movement of currents
Heat Capacity- the ability to absorb energy when water is heated
The Conveyor System moves water masses from the surface to deep oceans and back again;
according to the density of the mass (this is responsible for currents)
Salty water flowing to the North Atlantic is cooled and sinks (high density). This is then joined
by the Antarctic waters, which extends into the Indian and Pacific oceans. The warmer surface
currents go in the opposite direction and return water to the North Atlantic.
This cycle has been interrupted in the past possibly due to unusually large amounts of fresh water in
the Atlantic
20.3
KristenBanta, KatieKeefer, CamrynEicher
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Climate is influenced by:
-Internal components- oceans, atmosphere, snow cover, sea ice, etc
-External factors- solar radiation, the Earth’s rotation, slow changes in our planet’s orbit, and the gaseous
make-up of the atmosphere
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Radiative forcing-the influence that something has on the energy balance of the atmosphere-ocean-land
system, if these change the system over time, they can lead to a change in climate
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If factors are positive- warming; if factors are negative- cooling
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How greenhouse gases work: light comes through atmosphere and is absorbed by Earth, its then
converted to heat energy at the Earth’s surface, then it radiates back through the atmosphere to space.
However, some natural greenhouse gases absorb some of the radiation and reradiate it towards the surface
again.
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Our climate depends on the Earth’s concentration of Greenhouse Gases
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Clouds reflect 21% of solar radiation away to space before it ever reaches the ground (called planetary
albedo; snow and ice also contribute to this)
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Volcanoes can lead to planetary cooling as radiation is reflected and scattered away.
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Aerosols help cancel out the warming effect of GHG’s. Sulfer dioxide reacts with compounds in the
atmosphere to form haze, which reflects and scatters sunlight and contributes to clouds.
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The depletion of the stratospheric ozone has led to the cooling of the lower stratosphere
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Solar variability likely influences temperature, ocean currents, and the jet stream
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100 years ago the concern of CO2 in the atmosphere was suggested, and since then people have been
monitoring levels, observing that they have greatly risen since the Industrial Revolution
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Use of fossil fuels is the main contributor to CO2 levels
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Carbon “sinks” absorb CO2 and keep it from accumulating at a more rapid rate in the atmosphere.
Examples are oceans, because of the CO2 uptake by phytoplankton, and terrestrial ecosystems, because of
their ability to sequester carbon
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Other GHG’s that add to the insulating effect of CO2 are water vapor, methane, nitrous oxide, ozone,
and chlorofluorocarbons
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Water vapor is the most abundant greenhouse gas and is a major factor in the “supergreenhouse effect”
(water vapor traps energy that has been radiated back into the atmosphere, which contributes to the heating
of the ocean surface and the lower atmosphere in the tropical pacific
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Positive feedback- temperatures of ocean and land rise, evaporation increases, water vapor
concentration rises, which causes more warming
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Methane is being added to the atmosphere faster than can be broken down by livestock, landfills, coal
mines, natural gas production, rice cultivation, and manure.
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Nitrous Oxide levels have increased from agriculture and the burning of biomass, and it stays in the
atmosphere for 114 years, which is why it is such a problem.
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Ozone levels have increased and become potent from automotive traffic and burning forests and
agricultural wastes
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All other anthropogenic(from livestock coal mines, natural gas production, rice cultivation, and manure)
sources added together trap as much infrared radiation as CO2 does
Evidence of climate change
In 1998, the Intergovernmental Panel on Climate Change (IPCC) to provide accurate/relevant info that
would help to understand human-induced climate change.
The IPCC established 3 working groups:
1.) Working group I- assess the scientific issues
2.) Working group II- evaluate the impact of global climate change and the prospects for adapting to it.
3.) Working group III- investigate ways of mitigating the effects.
The work of the IPCC has been guided by two basic questions:
-Risk assessment: is the climate system changing, and what is the impact on society and ecosystems?
-Risk management: How can we manage the system through adaption and mitigation?
1. An Increasing Body of Observations Gives a Collective Picture of a warming World and Other
Changes in the Climate System
1990-2000 was the hottest decade ever recorded.
Scientists have puzzled over the absence of a more direct correlation between CO2 and global
atmospheric temperatures over the last several decades because their calculations predict that
temperatures should be much higher than the temperature has actually been.
-Their reasoning is that sulfate aerosol in the industrialized regions of the Northern Hemisphere appears
to be canceling out much of the greenhouse warming over those regions. The cooling effects of the
aerosol occur over the regions most responsible for greenhouse gas emissions.
With global warming, the sea level has been rising due to two factors: thermal expansion as oceans warm
and the melting of glaciers and ice fields.
2. Emissions of GHGs and Aerosols Due to Human Activities Continue to Alter the Atmosphere in
Ways That Are Expected to Affect the Climate
The IPCC examined long-term records of GHGs and sulfate aerosols and demonstrated that these agents
were on the increase in the atmosphere and were exerting a predictable forcing impact on the climate
system.
-Carbon dioxide, Nitrous oxide, methane, and sulfate aerosols have been on the rise since the early 1800s.
3. Confidence in the Ability of Models to Project Future Climate Has Increased
Weather conditions 72 hours or more have become quite accurate.
Climatologists employ the same powerful computers used for weather forecasting and have combined
global atmospheric circulation patterns with ocean circulation and radiation feedback from clouds to
produce coupled general circulation models (CGCMs) that are capable of stimulation long-term climatic
conditions.
4. There is New and Stronger Evidence That Most of the Warming Observed Over the Last 50
Years Is Attributable to Human Activities
In 1995, in its second assessment report, the IPCC stated cautiously, “The balance of evidence suggest a
discernible human influence on global climate.” In the third, the tone of consensus had shifted, to the
more definite statement that anthropogenic GHGs have “contributed substantially to the observed
warming over the last 50 years.”
5. Human Influences Will Continue to Change Atmospheric Composition Throughout the 21st
Century.
The IPCC predicts that CO2 will be the dominant greenhouse gas with the greatest influence on climate.
20.3 – Global Climate Change
- The major consequences of the rise in greenhouse gases, is the rise in temperature; this will
result in major impacts such as: regional climatic changes, and a rise in sea level.
- According to IPCC assessments, temperature is expected to rise 1.4 to 5.8’C over the period of
1990-2100.
- Any rise in temperature at all, even anything minute such as 1-2’C, can have dramatic weather
and climate changes.
- Air in the troposphere moves very quickly, so what one country does to it, can easily affect
another downwind.
- Though outcomes may be devastating to ecosystems and environments, some benefits come
from “Global Warming” such as: longer growing seasons for crops and plants, warmer winters
where usually the winters are brutal, but once again the net harm will likely outweigh the
benefits.
- The rise in temperature is melting the polar ice caps, the Greenland ice sheet is the main
concern. If completely melted, sea levels are expected around 7 meters in rise. Remember
though, there is great uncertainty in the magnitude of the rise in sea levels.
- The estimated rise in sea levels is only extended through the next century, but the impact will
be greater beyond the years of 2100. Once the atmospheric gases are stabilized , temperatures
and sea levels will continue to rise for a myriad of years because of slow response time of oceans.
- Global Change Research Act of 1990, congress mandated assessments of research on global
climate change and other implications for the 21st century.
Responses to Climate Change 20.4
Adaptation: Changing current habits to be able to survive.
Mitigation: Take actions to reduce emissions.
Framework Convention on Climate Change: One of the documents signed at the UNCED Earth Summit
meetings that agreed to certain steps.
Kyoto Protocol: A meeting held in Japan during December of 1997 in which various nations agreed to limit
the amount of CO2 and GHGs.
Carbon Credit Trading: one of the current approaches agreed to in the Kyoto Protocol that reduces GHGs
by allowing developing nations are able to get cleaner technology.
Global Climate Change Initiative (GCCI): February 2002, a plan was made to reduce emissions intensity by
18% over the next 10 years. (didn’t happen, actually rose 14%)
Emissions Intensity: the ratio of greenhouse gas emissions to economic output (GDP)
Why should we respond to the change? : the three principles
1. Precautionary Principle- even if there is no scientific certainty, we should still prepare for the worse.
2. Polluter Pays Principle- polluters should pay for whatever their pollution costs. We did the damage
so we should fix it.
3. Equity Principle- it isn’t right that the rich nations use all of the resources that cause pollution and
global warming while the underdeveloped nations suffer from the pollution already.
The Two Responses
1. Mitigation- plans to reduce emissions
a. Limit GHG (Green House Gas) emissions worldwide (limit the use of fossil fuels in industry
and transportation.
b. Invest in renewable energy sources: wind, solar, thermal, photovoltaics, hydrogen-powered
vehicles, and geothermal energy.
c. Remove fossil-fuel subsidies. Instead make it a hassle to use them and don’t allow for oil
and gas exploration
d. Encourage the development of nuclear power.
e. No deforestation.
f. Stricter energy conservation rules.
g. Lower transportation use. Carpools and mass transit when possible and more efficient cars.
h. Sequester CO2 gases. Convert it into liquid form and pump it into the deep ocean where it
will preserve it as a solid mass.
i. Slow the growth of human population.
President George W. Bush declined to reaffirm the actions stated in the Kyoto Protocol because he
believed it unfair to exempt the developing nations and also because it would harm the U.S. economy.
Mitigation is needed to slow down the imminent change in climate so the ability to adapt is just as
essential.
2. Adaptation: - Although it would be helpful to all, this mostly relates to underdeveloped countries
because they lack the money to pay for other resources.
a. Things that will be affected by climate change include a reduce amount of crops in warmer,
tropical regions due to droughts and heat, while temperate regions will be more abundant.
Water is also likely to become scarcer and the increased heat and moisture in other areas will
result in disease and lethal heat waves. Weather will also change as storms become more
frequent and the sea level rises. Poorer regions cannot handle all of these changes as of yet
and a larger loss of life will result. Just a fun fact, 96% of disaster related deaths are in
developing countries.
p.s. In case you didn’t know, the amount of green house gas emissions has increased.
20.5 notes 1st half: pgs- 564-568
Radiation and Importance of Shield:
The stratospheric ozone layer protects the Earth from harmful
ultraviolet radiation. The main culprit for its depletion can be traced back to a group of chemicals known a
CFCs. When absorbed by biological tissue, ultraviolet radiation (UV) damages proteins and DNA molecules
at the surfaces of all living things (a sunburn). The ozone layer filters out over 99% of ultraviolet radiation, so
the fraction we feel on Earth isn’t necessarily deadly. Still, even a small amount of UVB radiation can cause
skin cancer and precancerous ailments. If there was no ozone layer, there would be no filter, and life would
probably not be able to survive. The ozone layer is also referred to as the ozone shield, because of its
protective properties.
There are two types of ultraviolet wavelengths: UVB radiation consists of wavelengths that range from 280 to
320 nanometers. UVA radiation consists of wavelengths from 320 to 400 nanometers.
Formation and Breakdown of the Shield:
Ozone is formed in the stratosphere when UV radiation
acts on oxygen molecules; the high-energy radiation causes some molecular oxygen to split into free oxygen
atoms (O2 + UVB O+O ). The free oxygen atoms in turn, combine with non-split, molecular oxygen to
form ozone ( O+O2 O3).
Not all of the molecular oxygen is converted to ozone though; free oxygen atoms can also be
combined with ozone molecules to form two oxygen molecules (O+O3 O2+O2). When the ozone
absorbs UVB, it is converted back to free oxygen and molecular oxygen (O3+UVB O+O2). This process
helps to create equilibrium through a continuous cycle of reactions of formations. Ozone concentration in
the northern hemisphere is highest in the summer and lowest in the winter. Ozone concentrations are highest
at the equator and diminish as latitude increases.
Halogens in the Atmosphere: Chlorofluorocarbons (CFCs) are a type of halogenated carbon; they are
nonreactive, nonflammable, nontoxic organic molecules in which both chlorine and fluorine atoms replace
some hydrogen atoms. The characteristic of reabsorbing heat and becoming hot has lead to the widespread
use of CFCs for things like: refrigerators, air conditioners, the production of plastic foam, a pressurizing agent
in aerosol cans, and so on.
Rowland and Molina: In 1974, chemists Sherwood Rowland and Mario Molina published a paper concluding
that CFCs could damage the stratospheric ozone layer, and as a result, would increase UV radiation and cause
more skin cancer. They were awarded the Nobel prize in 1995. Molina and Rowland explained that CFCs be
subjected to intense UV radiation in the stratosphere, thus making them unstable. This instability would
allow the CFCs to break apart and release free chlorine atoms, ultimately releasing all of the chlorine of a
CFC molecule. The free chlorine atoms would then attack the stratospheric ozone and form chlorine
monoxide and molecular oxygen. Two molecules of chlorine monoxide could react to release even more
chlorine and a oxygen model.
This whole process is called the chlorine catalytic cycle, because chlorine is continuously regenerated as it
reacts to ozone. Chlorine is a catalyst in this situation; also, every chlorine atom has the potential to break
down 100,000 molecules of ozone. CFCs are thus deemed to be dangerous because they act as transport
agents that continuously move chlorine atoms into the stratosphere.
EPA Action: the EPA banned the use of CFCs in aerosol cans in the U.S. in 1978. Manufacturers switched to
non-damaging substitutes, such as butane. Atmospheric scientists reason that any substance carrying reactive
halogens to the stratosphere has the potential to deplete ozone. Chemically similar to chlorine, bromine, used
as a common soil fumigant and pesticide, also attacks ozone and forms a monoxide in a catalytic cycle.
In 1985, British atmospheric scientists working in Antarctica reported a hole in the ozone layer
over the South Pole. The area in question is roughly the size of the United States and has ozone levels 50%
below normal. So far, the limited time and area of ozone depletion there have not apparently brought on and
catastrophic ecological events so far.
20.5 notes 2nd half from pages. 568- 570
Arctic Hole?
There has been a close watch on the arctic because of severe ozone depletion.
No holes have been developed to date.
Ozone depletion occurs in the arctic with levels as much as 20-25% lower than normal during the
Arctic winters, but it intensifies during the colder winters like in the years 1999 and 2000.
Denitrification takes places and it allows more chlorine and bromine to remain in their reactive
forms.
Further Ozone Depletion.
Reports from the World Ozone Data Center in Toronto, Canada revealed that ozone depletion levels
of 3 and 6% over period of 1997-2001 of the Northern and Southern Hemispheres.
According to recent reports, ozone loss in the upper stratosphere has diminished and concentrations
of substances like chlorine and bromine in the troposphere are now declining.
Ozone losses cause skin cancer to many people in the U.S because it has allowed more UVB
radiation to reach Earth. There have been increased UVB levels, especially at high altitudes.
Coming to Grips with Ozone Depletion
There was a meeting in Montreal, Canada in 1987 to address ozone depletion and member nations
reached an agreement called Montreal Protocol, to scale CFC production back 50% by 2000.
The ozone losses during the late 1980s were greater than expected, so an amendment was adopted in
June 1990, it required nations to phase out the major chemicals destroying the ozone layer by 2000 in
developed countries and by 2010 developing countries.
Quantities of CFCs are still being manufactured to satisfy legitimate demand in the developing
countries. Some have been smuggled into the U.S leading to big fines, jail time, and the recovery of
tons of the banned chemicals.
The U.S was the leader in the production and use of CFCs and other ozone-depleting chemicals,
with du Pont Chemical Company being the major producer.
Du Pont spoke in opposition to three bills introduced into the 104th Congress in Sept. 1995, the bills
were made to terminate U.S participation in, and compliance with, the CFC banning protocols.
Title VI, ”Protection Stratospheric Ozone” is a comprehensive program that restricts the production,
use, emissions, and disposal of an entire family of chemicals identified as ozone depleting.
In most industrialized countries CFCs are no longer being produced or used instead substitutes have
been taking place like HFCs which contain no chlorine and no ozone-depleting potential. CFCs have
been slowly declining and scientists predict the ozone shield will recover entirely by 2050.
Final Thoughts
The ozone story is remarkable, from the first warnings, through the development of the
Montreal Protocol and the final steps of CFC phase out. All of these developments must be
taken during the 21st century to prevent catastrophic global climate change.
Chapter 21
21.1
Figures
Figure 21-2: The Hydroxyl Radical- The hydroxyl group (OH) missing the electron. It is a natural cleansing
agent of the atmosphere. It is highly reactive, readily oxidizes many pollutants upon contact, and thus
contributes to their removal from the air.
The figure shows a simplified model of atmospheric cleansing by the hydroxyl radical
PCS Port al.lnk
The first step is the photochemical destruction of ozone, which is the major process leading
to ozone breakdown in the troposphere.
The second step produces hydroxyl radicals, which react rapidly with many pollutants,
converting them to substances that are less harmful or that can be returned to Earth via
precipitation.
Figure 21-3: Industrial and photochemical smog
Industrial smog, or gray smog, occurs when coal is burned and the atmosphere is humid.
Photochemical smog, or brown haze, occurs when sunlight acts on vehicle pollutants.
Figure 21-5: Temperature inversion may cause episodes of high concentrations of air pollutants.
Normally, air temperatures are highest at ground level and decrease at higher elevations.
In a temperature inversion, a layer of warmer air overlies cooler air at ground level.
Reading Notes 21-1
The atmosphere contains numerous gases. The most prominent gases are N2
(nitrogen) 78.8% O2 (oxygen) 20.95% Ar (argon) .93% CO2 (carbon dioxide) .03%, as well
as water vapor which ranges from 0 to 4%
Determining the amount of pollution in the air
1.
The amount of pollutants entering the atmosphere.
2.
The amount of space into which the pollutants are dispersed.
3.
The mechanisms that remove pollutants from the air.
Natural elements which clean the atmosphere are Hydroxyl Radical which oxidizes
pollutants, Sea salt spray, and microorganisms in soil, which keep the soil from becoming
toxic.
The photochemical breakdown of tropospheric ozone is the major source of the
hydroxyl radical.
Industrial smog is a combination of smoke and fog. It is a mixture of soot, sulfurous
compounds, and water vapor.
Photochemical Smog is produced when several pollutants from automobile
exhausts-nitrogen oxides and volatile organic carbon compounds-are acted on by sunlight
Temperature inversion is when cold air is held below hot air in the atmosphere.
When such temperature inversions occur, pollutants can build to dangerous levels
promoting health problems.
Smog causes headaches, nausea, and eye and throat irritation.
Air pollution is not limited to just people. In recent years it has affected certain tree
species as well as farming
SECTION 21.2
A lot of the air pollutants are from combustion of coal, gasoline, and refuse.
Suspended particle matter comes from soot, smoke metals, and carbon from combustion; dust, salts, and dirt
from wind erosion. Its a complex mixtures of solid particles and aerosols in the air and can be a carcinogenic.
Volatile organic compounds come from incomplete combustion, evaporation of solvents, and emissions from
plants. It is a mixture of compounds, major agent of ozone formation.
Carbon monoxide comes from incomplete combustion of fuels. It is an odorless tasteless gas; poisonous
because of ability to bind to hemoglobin and block oxygen delivery to tissues.
Nitrogen oxides come from nitrogen gases due to high combustion temperatures. Its a reddish brown gas
and lung irritant capable of producing acute disease, major source of acid rain.
Sulfur oxides are combustion of leaded fuels and solid wastes. It’s a poisonous gas that impairs breathing,
major source of acid rain.
Lead is combustion of leaded fuels and solid wastes. It is toxic at low concentrations, accumulates in body
and can lead to brain damage and death.
Air toxics come from industry and transportation. Toxic chemicals of many kinds are air toxics such as
benzene, asbestos, and vinyl chloride.
Over 80% of carbon monoxide pollution comes from transportation; as a matter of fact almost all pollution
comes from transportation or fuel combustion.
EPA is the environmental protection agency. They follow the air quality by measuring the ambient
concentrations of the pollutants at thousand of monitoring stations across the country. We have lost a lot of
the pollutants in the past twenty years, mainly thanks to the clean air act.
Lead is emitted the least out of particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide,
and lead. Lead used to be added to gas to prevent knocks in the engine but they stopped doing that.
Toxics and radon also just kind of float around in the air a little bit and can sometimes be emitted into small
businesses through the ground.
Ozone is a secondary pollutant. It is formed up between nitrogen oxides and volatile organic compounds.
The sunlight propels said things and it is called photochemical oxidants. Before the industrial revolution the
ozone concentrations ranged from 10 to 15 ppb, now they are from 20 to 50 ppb. Polluted air can contain
150 ppb or more. This is unhealthy for long periods of times. Nitrogen oxide absorbs light energy and splits
to form nitric oxide and atomic oxygen which rapidly combines with oxygen gas to form ozone
Sulfuric and nitric acids can be considered secondary pollutants since they are products of sulfur dioxides and
nitrogen dioxides. These are in acid rain
2.1 continued…
ricky owens
Acid Deposition
Acid precipitation- refers to any precipitation that is more acidic than usual.
Acid deposition- dry acidic particles are also found in the atmosphere, the combo of precipitation and dry
particle fallout its acid deposition
Svante Oden was a Swedish scientist who was the first documented acidification of lakes in other parts of
Europe and Great Brittan.
Problem: in America and other industrial regions in the world have 10 to 1000 times more acidic precipitation
than usual.
Acids and Bases
Acid- any chemical that releases hydrogen ions when dissolved in water.
The higher the amount of hydrogen in a solution the more acidic it is.
Base- is any chemical that realeases hydroxide ions.
pH- the amount of hydrogen ions in a solution, expressed as 0 being highly acidic through 7 which is water
and up to 14 being highly basic.
pH scale uses powers of ten, so pH 4 is ten times more acidic than pH 5.
Extent and Potency of Acid Precipitation
Rain is always slightly acidic at 5.6 and in the presence of Carbon dioxide absorbs making it less than pH 5.5
The pH of most precipitation in the eastern part of America which is the lowest around.
In Los Angeles scientists found fog water with the pH of 2.8.
Sources of Acid Deposition
Chemical analysis of acid precip. in North America and Europe reveals the presence of two acids SULFURIC
ACID and NITRIC ACID.
*Burning fossil fuels produce sulfur dioxide and nitrogen oxides, so the source of the acid deposition is
evident. These oxides enter the troposphere in large quantities form both anthropogenic and natural
resources. Once in the troposphere, they are oxidized by hydroxyl radicals to sulfuric and nitric acids, which
dissolve rapidly in water or adsorb to particles and brought down to reach in acid deposits.
Anthropogenic sources are pollution that comes from humans
Natural sources come from natural occurring events
Anthropogenic sources estimate 100 to 130 million tons of sulfur dioxide per year
Natural sources estimate 30 to 40 million tons
The EPA (environmental protection agency) passed the clean air act to lower the amount of emissions put
into the air annually.
21.3 Impacts of Air Pollutants
Introduction: Air pollution consists of any pollutants that are in the air, which mix with the normal
constituents of air. Rarely, if ever, only a single pollutant is involved in pollution. It is usually a combination
of pollutants that act together to harm a person’s health. However, recently there have been many feats to
lower these pollutant levels.
-In 1996, the EPA mandated the elimination of leaded gasoline. This has lead to less cases of lead poisoning
due to less harmful emissions from the burning of gasoline.
-Fatal heart attacks can be triggered by moderate air pollution. This, changes up the heart’s cardiac rhythm,
causing death frequently for those with heart disease.
Effects Air Pollution has on Human Health
a.
b.
c.
d.
e.
Air pollution disasters have caused death!
It damages respiratory organs such as the lungs.
Many effects can be seen over a long period of time such as asthma.
Lead poisoning can occur.
Cancer can develop due to carcinogenic particles which are known to cause cancer.
Figure 21-16 The Respiratory System
-Millions of tiny sacs called alveoli, which are surrounded by capillaries are very important to human life.
These diffuse oxygen into the blood and remove Carbon Dioxide.
-When these are damaged, the body cannot function as it normally would. This can have an outcome of a
shortened life, or death due to cancers which develop because of intense damage.
Effects on the environment
Crop damage
-Dying off of vegetation in large urban areas and the damage to crops,orchards, and forests downwind of
urban centers are cause mainly by exposure to ozone and other photochemical oxidants.
-Crop damage by ozone ranges from 2 billion to 6 billion per year.
-Figure 21-19 explains how damage to important crops such as soybeans, corn, and wheat are observed at
common ambient levels of ozone.
-North America, Europe, and Eastern Asia produce 60 % of the worlds food and produces 60 % of the
worlds air pollution.
Forest Damage
-Forest under stress from population are more susceptible to damage by insects and other pathogens than
are unstressed forests.
-Heavy metals, ozone, and acids carried in by clouds from the Midwest were implicated in the death of red
spruce in Vermont’s Green Mountains.
-In Los Angeles 50% of the trees died in some areas.
-As a result of air pollution control, those same areas have shown significant improvement in tree growth in
recent years.
Effects on materials and Aesthetics
-Walls, windows and other exposed surfaces turn gray and dingy as particulates settle on them.
-Paints and fabrics deteriorate more rapidly, and the sidewalls of tires and other rubber products become hard
and checkered with cracks because of oxidation by ozone.
Visibility
-Regional haze comes from particulates and gases originating hundreds of miles away.
-Epa established a Regional Haze Rule in 1999 aimed at improving the visibility at 156 national parks and
wilderness areas.
-regulations call on all 50 states to establish goals for improving visibility and to develop long term strategies
for reducing emissions.
Effects of acid deposition
Acid deposition alters and can destroy ecosystems
Impact on Aquatic ecosystems
-The ph of an environment is extremely critical because its affects the function of virtually all
enzymes,hormones,and other proteins in the bodies of all organisms living in that environment.
-Most freshwater lakes, ponds, and streams have a natural ph in the range of 6 to 8.
-Eggs, sperm, and developing young of these organisms are especially sensitive to changes in ph
-as aquatic ecosystems become acidified, higher organisms die off.
-Figure 21-12 shows that acid precipitation may leach aluminum and various heavy metals from the soil as
water percolates through it.
Buffer, the Acid Slayer
-A system may be protected from changes in ph by a buffer, a substance that, when present in a solution, has
a large capacity to absorb hydrogen ions and thus maintain the ph at a relatively constant value.
Limestone is a natural buffer that protects lakes from the effects of acid precipitation.
-regions that are sensitive to acid precipitation are those containing much granitic rock that does not yield
good buffers.
Impact on forest
-most of the damage from acid precipitation to forests is due to chemical interactions within the forest soils.
-Sustained acid precipitation at firsts adds nitrogen and sulfur to the soils, which stimulate tree growth.
-the combination of aluminum and the increasing scarcity of calcium is essential to plant growth.
-in Europe, dying forests are a serious problem in many parts.
-because of variations in the buffering capacity of soils and the differing amounts of sulfur and nitrogen
brought in by acid precip, forests are affected to varying degrees.
Impact on humans and their artifacts
-limestone and marble are favored materials for the outside of buildings and for monuments.
-reaction between acid and limestone are causing structures to erode which cause the monuments and
buildings to dissolve and crumble.
-although decay of such artifacts is a tragic loss in itself, it also stands as a grim reminder of how are
dissolving away the buffering capacity of ecosystems.
-increased acidity in water mobilizes lead from the pipes used in some old plumbing systems and from the
solder used in modern copper systems.
Chapter 21.4 Notes
(Breathing Air Pollution under Control)
Standards and Regulations:
The Clean Air Act was passed by Congress in 1970 and together with amendments passed in 1990 and 1977
is the foundation of air-pollution in the United States. Administered by the EPA, the Clean Air Act sets
ambient standards, levels which must be achieved to protect the environment and the health of the nation’s
populace.
The CAA implemented the standards for four of the primary pollutants – particulates, sulfur dioxide, carbon
monoxide, and nitrogen oxides – along with a fifth pollutant, ozone. With the addition of lead, these
pollutants became known as the criteria pollutants. The status of these pollutants are governed by the
National Ambient Air Quality Standards (NAAQS). The primary standard for each pollutant is based on the
presumed highest level of presence which can be tolerated by humans without noticeable ill effects with a
reduction of 10-50% for safety.
National Emission Standards for Hazardous Air Pollutants (NESHAPs) have also been issued for eight toxic
substances: arsenic, asbestos, benzene, beryllium, coke-oven emissions, mercury, radionuclides, and vinyl
chloride. The EPA has since named 188 toxic air pollutants the agency must track and regulate.
Control Strategies:
Command and control is a strategy used by the EPA to make air pollutant emissions meet the ambient
criteria regarding air pollution. This strategy hasn’t been very effective as, even today, 124 metropolitan areas
in this nation fail to meet the EPA’s standards.
Managing Ozone:
Ozone is a secondary pollutant that can only be addressed by the compounds that lead to formation. Point
sources (industries) account for 30% of VOC emissions. Area sources (dry cleaners, small emitters, print
shops, household products) represent 20%. In the last 20 years these emissions have declined 33% under
strict EPA, state and local government regulation. However, both VOCs and NO are crucial for ozone
generation and a balance must be maintained.
A revised standard of 0.12 to 0.08ppm was announced in 1997 with strong opposition from industry groups.
Implementation was set back to 2004. The new standard was expected to prevent a substantial amount of
damage to vegetation. The EPA also established the Ozone Transport Rule which sets No budgets for
Midwestern and Southern States that had an estimated No reduction of 75-85%.
EPA has also identified maximum achievable control technologies. Plants are granted emission allowances
under the Clean Air Act of 1990.
21.5
Unresolved Issues
I.
Unresolved Issues
A.
Costs versus Benefits
1.
Critics have charged that air pollution controls are not cost effective: the benefits
are not nearly as the great as the costs
a)
They are lost opportunities for economic growth + tend to disregard the
costs avoided (from improved health)
2.
OMB (Office of Management and Budget) found that yearly benefits of
environmental regulations ranged from $121-$193 billion to $37-$43 billion
a)
This confirms the former analysis of the benefits of the Clean Air Act
B.
New Source Review
1.
The Clean Air Act requires all power plants and other polluting industrial facilities
built after 1970 to incorporate “best available” pollution control technology
C.
D.
a)
The CAA exempted all older facilities from having to install new pollution
controls and chose to require them to do so only when they upgrade their facilities
in any way that would increase pollution
b)
In 2003 Vice President Cheney changed the rules so that factories and
power plants would no longer be required to update their pollution controls, unless
the improvements or changes involved more than 20% of the entire facility’s value
(1)
State officials and environmental groups charged that the Bush
administration was rewarding the utility industry for its multi-million-dollar
contributions to the 2000 presidential and congressional Republican
campaigns
Clear Skies
1.
Clear Skies Act: would change the CAA regulations for power plants by addressing
3 major pollutants: SO(subscript)2, NO(subscript)x, and mercury
a)
SO2: cut emissions to 3 million tons
b)
NOx: cut emissions to 1.7 million tons
c)
Mercury: 15 tons
d)
All of these amounts are to be phased gradually until 2018
Getting Around
1.
Raising CAFE (corporate average fuel economy) standards would help address:
a)
Our dependence on imported oil
b)
All of the health issues from smog and particles
c)
Carbon dioxide emissions that are bringing on global climate change
2.
Switching from gasoline to electric cars transfers the site of pollution emission from
the moving vehicle to the power plant
3.
Hybrid electric vehicle: an electric car with an electric generator to charge the
batteries. The most fuel-efficient cars in the country
4.
The “partial zero-emission vehicle”: a super-clean gas car that emits only 5% of the
pollutants of a standard new car
a)
Does not do anything for carbon dioxide emissions: engines still large and
fuel hungry
5.
Increase in mass-transit ridership (buses, subways, and commuter rail lines)
a)
24% faster than highway or air-transport ridership
b)
Encourage people to live closer to their workplaces