Air Pollution, Climate
Change and Ozone
Depletion
General
Information
AIR POLLUTION
Some primary air pollutants may react with one
another or with other chemicals in the air to form
secondary air pollutants.
Figure 19-3
Major Air Pollutants
Carbon oxides:
Carbon monoxide (CO) is a highly toxic gas that
forms 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).
• It is not regulated as a pollutant under the U.S. Clean
Air Act.
Major Air Pollutants
Nitrogen oxides and nitric acid:
Nitrogen oxide (NO)- forms when N and O gas
in air reacts in High Temp. automobile engines
and coal-burning plants. NO can also form
from lightening and certain soil bacteria.
• NO reacts with air to form NO2.
• NO2 reacts with water vapor to form nitric acid
(HNO3) and nitrate salts (NO3-) = acid deposition.
Major Air Pollutants
Sulfur dioxide (SO2) and sulfuric acid
Two-thirds come from human sources, mostly
combustion (S+ O2  SO2) of sulfurcontaining coal and oil refining
SO2 in the atmosphere can be converted to
sulfuric acid (H2SO4) and sulfate salts (SO42-)
= acid deposition.
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.
SPM is responsible for about 60,000 premature
deaths a year in the U.S.
Major Air Pollutants
Ozone (O3):
Is a highly reactive gas that is a major
component of photochemical smog.
It can
• Cause and aggravate respiratory illness.
• Can aggravate heart disease.
• Damage plants, rubber in tires, fabrics, and paints.
Major Air Pollutants
Volatile organic compounds (VOCs):
Most are hydorcarbons: methane,industrial
solvents, trichlorethylene (TCE), benzene, and
vinyl chloride.
VOCs can cause cancer, blood disorders, and
immune system damage.
Major Air Pollutants
Radon (Rn):
Is a naturally occurring radioactive gas found in
some types of soil and rock.
It can seep into homes and buildings sitting
above such deposits.
Secondary
Pollutants
Form when primary
pollutants react
URBAN OUTDOOR AIR
POLLUTION
Industrial smog is a mixture of sulfur
dioxide, droplets of sulfuric acid, and a
variety of suspended solid particles emitted
mostly by burning coal.
In most developed countries where coal and
heavy oil is burned, industrial smog is not a
problem due to reasonably good pollution
control or with tall smokestacks that transfer
the pollutant to rural areas.
Sunlight plus Cars Equals
Photochemical Smog
Photochemical smog is a mixture of air pollutants
formed by the reaction of nitrogen oxides and
volatile organic hydrocarbons under the influence
of sunlight.
Sunlight plus Cars Equals
Photochemical Smog
Mexico City is one
of the many cities
in sunny, warm,
dry climates with
many motor
vehicles that suffer
from
photochemical
smog.
Figure 19-4
Factors Influencing Levels of
Outdoor Air Pollution
Outdoor air pollution can be reduced by:
settling out, precipitation, sea spray, winds, and
chemical reactions.
Outdoor air pollution can be increased by:
urban buildings (slow wind dispersal of
pollutants), mountains (promote temperature
inversions), and high temperatures (promote
photochemical reactions).
Temperature Inversions
Cold, cloudy weather in a valley surrounded
by mountains can trap air pollutants (left).
Areas with sunny climate, light winds,
mountains on three sides and an ocean on
the other (right) are susceptible to
inversions.
Figure 19-5
Descending warm air mass
Warmer air
Inversion layer
Inversion layer
Sea breeze
Increasing
altitude
Decreasing
temperature
Fig. 19-5, p. 447
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.
ACID DEPOSITION
Acid deposition consists of rain, snow, dust,
or gas with a pH lower than 5.6.
Figure 19-6
Wind
Transformation to
sulfuric acid
(H2SO4) and nitric
acid (HNO3)
Nitric oxide (NO)
Windborne ammonia gas and
particles of cultivated soil
partially neutralize acids and
form dry sulfate and nitrate
salts
Sulfur dioxide
(SO2) and NO
Acid fog
Dry acid deposition
(sulfur dioxide gas and
particles of sulfate and
nitrate salts)
Farm
Ocean
Lakes in deep
soil high in
limestone are
buffered
Wet acid depostion
(droplets of H2SO4
and HNO3 dissolved
in rain and snow)
Lakes in shallow soil
low in limestone
become acidic
Fig. 19-6, p. 448
ACID DEPOSITION
pH measurements in relation to major coalburning and industrial plants.
Figure 19-7
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.
ACID DEPOSITION
Figure 19-8
ACID DEPOSITION
Air pollution is
one of several
interacting
stresses that can
damage,
weaken, or kill
trees and pollute
surface and
groundwater.
Figure 19-9
Emissions
SO2
Acid H O
2 2
deposition
PANs
NOx
O3
Others
Reduced
photosynthesis
and growth
Direct damage to
leaves & bark
Tree death
Soil acidification
Leaching
of soil
nutrients
Acids
Release of
toxic metal
ions
Susceptibility
to drought,
extreme cold,
insects,
mosses, &
disease
organisms
Root
damage
Reduced nutrient
& water uptake
Lake
Groundwater
Fig. 19-9, p. 451
Solutions
Acid Deposition
Prevention
Reduce air pollution
by improving
energy efficiency
Cleanup
Add lime to
neutralize
acidified lakes
Reduce coal use
Increase natural
gas use
Increase use of
renewable energy
resources
Add phosphate
fertilizer to
neutralize
acidified lakes
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
Air Quality is better in US; EPA
estimates since 1970
Particulate Matter (PM)- down 78%
Carbon Dioxide (CO2)- down 23%
Nitrogen Dioxide (Nox)- up 14%
Lead (Pb)- down 98%
Sulfur Dioxide (SO2)- down 32%
Air quality is worse in developing countries:
Mexico City & Beijing: air exceeds WHO
standards 350 days/year
INDOOR AIR POLLUTION
Indoor air pollution usually is a greater threat to
human health than outdoor air pollution.
According to the EPA, the four most dangerous
indoor air pollutants in developed countries are:
Tobacco smoke.
Formaldehyde.
Radioactive radon-222 gas.
Very small fine and ultrafine particles.
Chloroform
Para-dichlorobenzene
Tetrachloroethylene
Formaldehyde
1, 1, 1Trichloroethane
Styrene
Nitrogen
Oxides
Benzo-a-pyrene
Particulates
Tobacco
Smoke
Asbestos
Carbon Monoxide
Radon-222
Methylene Chloride
Fig. 19-11, p. 453
INDOOR AIR POLLUTION
Household dust mites
that feed on human
skin and dust, live in
materials such as
bedding and furniture
fabrics.
Can cause asthma
attacks and allergic
reactions in some
people.
Figure 19-12
Case Study: Radioactive Radon
Radon-222, a
radioactive gas
found in some
soils and rocks,
can seep into
some houses and
increase the risk
of lung cancer.
Sources and paths of entry
for indoor radon-222 gas.
Figure 19-13
HEALTH EFFECTS OF AIR
POLLUTION
Normal human lungs (left) and the lungs of a
person who died of emphysema (right).
Figure 19-15
Air Pollution is a Big Killer
Each year, air pollution prematurely kills
about 3 million people, mostly from indoor
air pollution in developing countries.
In the U.S., the EPA estimates that annual
deaths related to indoor and outdoor air
pollution range from 150,000 to 350,000.
According to the EPA, each year more than
125,000 Americans get cancer from breathing
diesel fumes.
Air Pollution is a Big Killer
Spatial distribution of premature deaths
from air pollution in the United States.
Figure 19-16
PREVENTING AND REDUCING
AIR POLLUTION
The Clean Air Acts in the United States
have greatly reduced outdoor air pollution
from six major pollutants:
Carbon monoxide
Nitrogen oxides
Sulfur dioxides
Suspended particulate matter (less than PM-10)
Using the Marketplace to Reduce
Outdoor Air Pollution
To help reduce SO2 emissions, the Clean
Air Act authorized an emission trading
(cap-and-trade) program.
Enables the 110 most polluting power plants to
buy and sell SO2 pollution rights.
Between 1990-2002, the emission trading
system reduced emissions.
In 2002, the EPA reported the cap-and-trade
system produced less emission reductions than
were projected.
Solutions:
Reducing Outdoor Air Pollution
There are a of ways to prevent and control
air pollution from coal-burning facilities.
Electrostatic precipitator: are used to attract
negatively charged particles in a smokestack
into a collector.
Wet scrubber: fine mists of water vapor trap
particulates and convert them to a sludge that is
collected and disposed of usually in a landfill.
Solutions:
Reducing Outdoor Air Pollution
There are a # of ways to prevent and control
air pollution from motor vehicles.
Because of the Clean Air Act, a new car today
in the U.S. emits 75% less pollution than did
pre-1970 cars.
There is and increase in motor vehicle use in
developing countries and many have no
pollution control devices and burn leaded
gasoline.
Solutions
Motor Vehicle Air Pollution
Prevention
Mass transit
Cleanup
Emission
control devices
Bicycles and
walking
Less polluting
engines
Less polluting fuels
Improve fuel efficiency
Car exhaust
inspections
twice a year
Get older, polluting
cars off the road
Give buyers large tax
write-offs or rebates for
buying low-polluting,
energy efficient
vehicles
Stricter
emission
standards
Fig. 19-19, p. 460
Solutions
Indoor Air Pollution
Prevention
Cover ceiling tiles & lining of AC
ducts to prevent release of mineral
fibers
Ban smoking or limit it to well
ventilated areas
Set stricter formaldehyde
emissions standards for carpet,
furniture, and building materials
Prevent radon infiltration
Use office machines in well
ventilated areas
Use less polluting substitutes for
harmful cleaning agents, paints,
and other products
Cleanup or
Dilution
Use adjustable fresh air
vents for work spaces
Increase intake of outside air
Change air more frequently
Circulate a building’s air
through rooftop green houses
Use exhaust hoods for stoves
and appliances burning
natural gas
Install efficient chimneys for
wood-burning stoves
Fig. 19-20, p. 461
Major Greenhouse
Gases
Increases in average
concentrations of three
greenhouse gases in the
troposphere between 1860
and 2004, mostly due to
fossil fuel burning,
deforestation, and
agriculture.
Figure 20-5
OZONE DEPLETION IN THE
STRATOSPHERE
Less ozone in the stratosphere allows for
more harmful UV radiation to reach the
earth’s surface.
The ozone layer keeps about 95% of the sun’s
harmful UV radiation from reaching the earth’s
surface.
Chlorofluorocarbon (CFCs) have lowered the
average concentrations of ozone in the
stratosphere.
In 1988 CFCs were no longer manufactured.
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and
leaving CFCl2.
Sun
Cl
UV radiation
The chlorine atom attacks
an ozone (O3) molecule,
pulling an oxygen atom off
it and leaving an oxygen
molecule (O2).
Summary of Reactions
CCl3F + UV Cl + CCl2F
Cl + O3 ClO + O2
Repeated
Cl + O Cl + O2
many times
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again.
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
molecule to form O2.
The chlorine atom
and the oxygen atom
join to form a chlorine
monoxide molecule
(ClO).
Fig. 20-18, p. 486
Human Impact (Positive)
Pollution Control Devices
Emission Control Devices – filter particles
Scrubbers – use water to filter particles
and gases
Catalytic Converters – on cars; finish
burning wastes to decrease CO
1-800-453-SMOG
International Climate Negotiations:
The Kyoto Protocol
Treaty on global warming which first phase
went into effect January, 2005 with 189
countries participating.
It requires 38 participating developed countries
to cut their emissions of CO2, CH4, and N2O to
5.2% below their 1990 levels by 2012.
Developing countries were excluded.
• The U.S. did not sign, but California and Maine are
participating.
• U.S. did not sign because developing countries such
as China, India and Brazil were excluded.
Moving Beyond the Kyoto
Protocol
Countries could work together to develop a
new international approach to slowing
global warming.
The Kyoto Protocol will have little effect on
future global warming without support and
action by the U.S., China, and India.
Law – Clean Air Act
1963 - first passage
1970, 1977 and 1990 - amended
Involves EPA
Sets standards for acceptable levels of sulfur
oxides, nitrogen oxides, ozone, carbon
monoxide, hydrocarbons, lead, & more
Provides pollution credits for industries that
utilize pollution-control devices+
Bush administration relaxed the rules
It established NAAQS and AQI
National Ambient Air Quality
Standards (NAAQS)
Sets acceptable concentrations for 6 “criteria”
pollutants that:
Threaten public health/the environment
over broad areas (non-point)
Are emitted in large quantities
CO, Pb, Nitrogen Oxides, Ozone,
Particulate Matter and Sulfur Dioxides
Air Quality Index (AQI)
Measures levels of 5 criteria pollutants
Forecast of daily air pollution levels
Purpose to educate and protect publicfocuses on health effects
Categories: green= good, yellow=
moderate, orange= unhealthy for sensitive
groups, red= unhealthy, purple= very
unhealthy
National Emissions Standards for
Hazardous Air Pollutants
Regulates emissions (from point sources)
For specific substances (air toxics w/
known or suspected serious health
effects (mutagens, carcinogens,
neurotoxins)
Tend to be localized, from point sources
Examples: Ammonia, chlorine, asbestos,
arsenic, mercury, benzene
Sources of Pollution
Agriculture
Fertilizers, animal wastes, etc.
Municipal Waste
Sewage, fertilizers, dumping
into drainage ditches, etc.
Industrial Waste
Chemicals
left over from
manufacturing, waste products, etc.
Point Source
Pollution
Non-Point
Source Pollution
Pollutants enter
traced to a
specific spot (such bodies of water over
large areas
as a factory or
sewage treatment Ex. Agricultural
plant) because it is fertilizer runoff and
discharged into
sediments from
the environment construction.
through pipes,
sewers or ditches.
Cultural Eutrophication

Eutrophication: the natural nutrient
enrichment of a shallow lake, estuary or slow
moving stream, mostly from runoff of plant
nutrients from the surrounding land.
 Cultural eutrophication: human activities
accelerate the input of plant nutrients (mostly
nitrate- and phosphate-containing effluents)
to a lake.

85% of large lakes near major population centers
in the U.S. have some degree of cultural
eutrophication.
Eutrophication
Definition
 enrichment
of a
body of water
from nutrients
such as
phosphorus or
nitrogen
Cause/Effect

Fertilizers,
erosion,
sewage, etc.
get into water
and the effect
is high
photosynthetic
productivity.
POLLUTION OF FRESHWATER
STREAMS

Flowing streams can recover from a
moderate level of degradable water
pollutants if they are not overloaded
and their flows are not reduced.

In a flowing stream, the breakdown of
degradable wastes by bacteria depletes DO
and creates and oxygen sag curve.

This reduces or eliminates populations of
organisms with high oxygen requirements.
Water Pollution Problems in
Streams

Dilution and decay of degradable, oxygendemanding wastes and heat in a stream.
Figure 21-4
Core Case Study: Using Nature to
Purify Sewage

Ecological wastewater
purification by a
living machine.

Uses the sun and a
series of tanks
containing plants,
snails, zooplankton,
crayfish, and fish (that
can be eaten or sold
for bait).
Figure 21-1
Fig. 21-4, p. 497
POLLUTION OF FRESHWATER
STREAMS
Most developed countries have sharply
reduced point-source pollution but toxic
chemicals and pollution from nonpoint
sources are still a problem.
 Stream pollution from discharges of
untreated sewage and industrial wastes
is a major problem in developing
countries.

Global Outlook: Stream Pollution
in Developing Countries

Water in many of
central China's
rivers are greenish
black from
uncontrolled
pollution by
thousands of
factories.
Figure 21-5
Case Study: India’s Ganges River:
Religion, Poverty, and Health

Religious beliefs, cultural traditions, poverty,
and a large population interact to cause
severe pollution of the Ganges River in India.
Very little of the sewage is treated.
 Hindu believe in cremating the dead to free the
soul and throwing the ashes in the holy Ganges.

Some are too poor to afford the wood to fully
cremate.
 Decomposing bodies promote disease and depletes
DO.

Case Study: India’s Ganges River:
Religion, Poverty, and Health

Daily, more than 1
million Hindus in
India bathe, drink
from, or carry out
religious
ceremonies in the
highly polluted
Ganges River.
Figure 21-6
POLLUTION OF
FRESHWATER LAKES

Dilution of pollutants in lakes is less effective
than in most streams because most lake
water is not mixed well and has little flow.
Lakes and reservoirs are often stratified and
undergo little mixing.
 Low flow makes them susceptible to runoff.


Various human activities can overload lakes
with plant nutrients, which decrease DO and
kill some aquatic species.
WATER POLLUTION: SOURCES,
TYPES, AND EFFECTS

Water pollution any chemical, biological, or
physical change in water quality that has a
harmful effect on living organisms or makes
water unsuitable for desired uses.

Point source: specific location (drain pipes,
ditches, sewer lines).
 Nonpoint source: cannot be traced to a single
site of discharge (atmospheric deposition,
agricultural / industrial / residential runoff)
Sediment Pollution
Definition
 Excessive
amounts of
suspended soil
particles that
eventually settle
out.
Causes
 Erosion
of
agricultural lands,
logging,
overgrazed
rangelands, strip
mines, and
construction.
Environmental Effects

Reduces light
penetration,
covering
aquatic
organisms,
bringing
insoluble toxic
pollutants into
the water,
and filling in
waterways.
Health Effects
Sediments carrying toxic chemicals.
 Disease-causing agents can also be
transported into water via sediments.

Sewage
Causes
 waste
water
from drains or
sewers (toilets,
washing
machines, and
showers) and
include human
wastes, soaps
and detergents.
Environmental
Effects
 Enrichment
–
nutrients like
nitrogen and
phosphorus
causing algal
blooms
Health Effects

when sewage
enter microorganisms
bloom, leaving
less Dissolved
Oxygen (DO)for
the fish, etc.,
and then they
die
 disease-
causing agents.
Disease-Causing Agents
Definition
Infectious organisms that cause
disease.
Causes
Comes from the wastes of infected
individuals.
Environmental Effects
 Municipal
wastewater contains bacteria,
viruses, protozoa, parasitic worms, and
other infectious agents that cause human
or animal diseases.
Health Effects
 Typhoid,
cholera, bacterial
dysentery, polio and infectious
hepatitis are some of the more
common bacteria or viruses that
are transmitted through
contaminated food and water.
Major Water Pollutants
and Their Effects

Water quality and dissolved oxygen
(DO) content in parts per million (ppm)
at 20°C.

Only a few fish species can survive in
water less than 4ppm at 20°C.
Figure 21-3
Inorganic Plant and Algal Nutrients

Chemicals such as nitrogen and phosphorus
that stimulate the growth of plants and algae.
Read “The Dead Zone”
Causes
 Nitrates
and phosphates come from
sources such as human and animal
wastes, agriculture
Environmental Effects

Inorganic nutrients encourage excessive
growth of algal and aquatic plants
Cultural Eutrophication. This causes
problems, including enrichment and bad
odor.
Organic Compounds
Causes

synthetic chemicals that are produced
by human activities; these included
pesticides, solvents, industrial chemicals
and plastics, and leachate (seepage)
from landfills.
Health Effects
 Hundreds
of synthetic organic
compounds are toxic and some of
these have been shown to cause
cancer or birth defects.
Environmental Effects
Pollutes
streams and
groundwater.
Inorganic Compounds
Causes
Examples include acids, salts, and
heavy metals.
 Sources - industries, mines, irrigation
runoff, oil drilling and urban runoff from
storm sewers.

Environmental Effects
toxic to aquatic
organisms.
Health Effects
 Lead
and mercury are poisonous. Mercury
exposure to developing fetuses - mental
retardations, cerebral palsy, and
developmental delays, causes kidney
disorders and damages nervous and
cardiovascular systems.
Low
levels of mercury in the brain cause
neurological problems such as headache,
depression, and quarrelsome behavior.
Radioactive Substances
 Contains
atoms of unstable isotopes
that spontaneously emit radiation
Radioactive Substances
Causes



mining and processing of radioactive
minerals such as uranium and
thorium.
The nuclear weapons industry use the
largest amounts.
Medical and scientific research
facilities also use them.
Health Effects
 Mutations,
birth defects, mental
retardation, genetic disease, leukemia,
cancer (breast, bone, thyroid, skin,
lung), burns, cataracts, male sterility.
Environmental Effects
Pollutes air, water and soil.
Thermal Pollution
Causes
 heated
water
produced
during certain
industrial
processes is
released into
waterways.
Environmental Effects
Decomposition of
wastes occurs
faster, Depletes
Oxygen
Health Effects
affects animals,
not humans.
Oil Spills
 When
a tanker accident happens, it gets lots
of publicity.
 But, more oil is released by normal operation
of offshore wells, washing tankers & from
pipeline or storage tank leaks.
 One estimate says that oil companies spill,
leak, or waste per year an amount of oil
equal to that shipped by 1000 huge Exxon
Valdez tankers.
Floating Oil
 Oil
coats the feathers of birds (especially
diving birds) and the fur of marine
animals, destroying the animals’ natural
insulation and buoyancy
 Many drown or die of exposure from loss
of body heat.
Mechanical Methods
Floating booms contain the oil spill or keep it
from reaching sensitive areas
 Skimmer boats are used to vacuum up some of
the oil into collection barges
 Absorbent pads or large feather-filled pillows
are used to soak up oil on beaches or in waters
that are too shallow for skimmer boats

Chemical Methods
Coagulating agents cause floating oil to clump
together for easier pickup or sink to the
bottom, where it usually does less harm.
 Dispersing agents break up oil slicks. However,
these can also damage some types of
organisms.
 Fire can also burn off floating oil, but crude oil
is hard to ignite.

Reducing Water Pollution through
Sewage Treatment

Septic tanks and various levels of
sewage treatment can reduce pointsource water pollution.
Figure 21-15
Reducing Water Pollution through
Sewage Treatment

Primary and Secondary sewage treatment.
Figure 21-16
Reducing Water Pollution through
Sewage Treatment

Advanced or tertiary sewage treatment:


Uses series of chemical and physical
processes to remove specific pollutants left
(especially nitrates and phosphates).
Water is chlorinated to remove
coloration and to kill disease-carrying
bacteria and some viruses (disinfect).
Reducing Water Pollution through
Sewage Treatment

Raw sewage reaching a municipal sewage
treatment plant typically undergoes:

Primary sewage treatment: a physical process
that uses screens and a grit tank to remove large
floating objects and allows settling.
 Secondary sewage treatment: a biological
process in which aerobic bacteria remove as
much as 90% of dissolved and biodegradable,
oxygen demanding organic wastes.
Water Treatment
Primary

Removes suspended and floating
particles, such as sand and silt, by
mechanical processes such as screening
and gravitational settling. The solid
material that is settled out is called
primary sludge.
Bar screens, grit
chambers,
primary
clarifiers,
digesters and
pre-aeration
Secondary

Uses microorganisms to decompose the
suspended organic material in
wastewater. Ex. trickling filters – where
wastewater trickles through aerated
rock beds that contain bacteria and
other microorganisms, which degrade
the organic material in the water.
Secondary (Cont.)
Or activated sludge process – wastewater is
aerated and circulated through bacteria-rich
particles; the bacteria degrade suspended
organic material. After several hours, the
particles and microorganisms are allowed to
settle out, forming secondary sludge.
 Use aeration basins, settling tanks and sand
filters

Tertiary
This includes a variety of biological, chemical and
physical processes used to remove phosphorus
and nitrogen, the nutrients most commonly
associated with enrichment. Tertiary treatment
can also be used to purify wastewater so that it
can be reused in communities where water is
scarce.
 Use chlorine as a disinfection and then chlorine is
removed by SO2 so it can be released into river.

Reducing Water Pollution through
Sewage Treatment
Sewage sludge can be used as a soil
conditioner but this can cause health
problems if it contains infectious
bacteria and toxic chemicals.
 Preventing toxic chemicals from
reaching sewage treatment plants
would eliminate such chemicals from
the sludge and water discharged from
such plants.

Reducing Water Pollution through
Sewage Treatment

Natural and artificial wetlands and other
ecological systems can be used to treat
sewage.

California created a 65 hectare wetland
near Humboldt Bay that acts as a natural
wastewater treatment plant for the town of
16,000 people.

The project cost less than half of the estimated
price of a conventional treatment plant.
Water Quality
United States

Groundwater contamination still occurs,
especially due to non-point source
pollution, but laws like the Safe
Drinking Water Act, Clean Water Act,
and Water Quality Act have helped in
the U.S.
Global Problems

According to the World Health
Organization, an estimated 1.4 billion
people still do not have access to
adequate sanitation systems.
Worldwide, at least 250 million cases of
water-related illnesses occur each year,
with 5 million or more of these resulting
in death.
Specific Water Quality Measures
Dissolved Oxygen
 The
amount of oxygen gas dissolved in a
given volume of water at a particular
temperature and pressure.
Carbon Dioxide
Enters aquatic systems from the
atmosphere and from respiration by
animals.
 The concentration of CO2 varies at
different depths because of
light/photosynthesis.

Nitrate

Contaminates shallow groundwater
(100 feet or less) and usually comes
from fertilizers. It’s a concern in rural
areas where 80-90% of the residents
use shallow groundwater for drinking.
This harms humans because it reduces
the blood’s ability to transport oxygen.
Sulfate
 Problem
because too much can
kill fish. Gets in water from
industrial processes and mining.
Iron
 Causes
problems because it
separates out of the water and
forms particulates (sediment), it
tastes bad if it gets in our water,
and can coat fish’s gills.
Groundwater problems in wells,
from natural minerals in rocks.
Phosphate –cultural
eutrophication
 Plant
nutrients that cause algae
blooms. It comes from detergents,
human wastes and fertilizers.
Coliform
 General
group of bacteria from
animal wastes. It uses up
available oxygen. Also causes
e-coli disease.
Giardia
 Organism
(protozoa) that can
cause diarrhea if you drink
unchlorinated water. It is a natural
organism that lives in the guts of
animals.
Chloride
 Part
of salts, but too many can
cause too much salt in the water.
Too much is bad; a little is okay. It
is naturally found in water, but can
come from pollution.
pH
 Too
high/too low can be bad;
fish like 6.5-9.5; acid mine
drainage can kill fish.
Hardness
 Calcium
and magnesium dissolved
in the water. A little is good (50400 ppm for fish is good), but very
low or high is a problem. Low is
more of a problem. Affects fish
eggs, poor bone development.
Turbidity
 Cloudiness/muddiness;
blocks
the light; coats fish gills.
Hard Water
Definition
 Calcium
and magnesium in the
water. Can cause problems with
cleaning clothes. Soap doesn’t
bubble as much.
Methods of Treating
Ion Exchange
 Substitute
sodium for calcium and
magnesium. Water softeners
usually do this.
Reverse Osmosis
 Membrane
system that allows
water to go through but calcium
and magnesium cannot.
Water Usage
Major Users – United States & global
Agricultural
users are the biggest
by volume, then industrial and
municipal.
POLLUTION OF
GROUNDWATER

U.S. EPA had completed the cleanup of
297,000 of 436,000 underground tanks
leaking gasoline, diesel fuel, home
heating oil, or toxic solvents.
Water Legislation
Safe Drinking Water Act

It required the EPA to determine the maximum
contaminant level, the max permissible amount
of any pollutant that might adversely affect
human health.
PREVENTING AND REDUCING
SURFACE WATER POLLUTION

Most developed countries use laws to set
water pollution standards, but such laws
rarely exist in developing countries.
The U.S. Clean Water Act sets standards for
allowed levels of key water pollutants and
requires polluters to get permits.
 EPA is experimenting with a discharge
trading policy similar to that for air pollution
control.

Clean Water Act
 Has
two basic goals:
 To
eliminate the discharge of pollutants in
U.S. waterways

To attain water quality levels that make these
waterways safe to fish and swim in.
Water Quality Act
•controlling toxic pollutant discharges
•control non-point sources of pollution
•authorized $18 billion for wastewater treatment
•address problems such as coastal estuaries,
the Great Lakes, and the Chesapeake Bay
RISKS AND HAZARDS
Risk is a measure of the likelihood that you
will suffer harm from a hazard.
We can suffer from:
Biological hazards: from more than 1,400
pathogens.
Chemical hazards: in air, water, soil, and food.
Physical hazards: such as fire, earthquake,
volcanic eruption…
Cultural hazards: such as smoking, poor diet,
unsafe sex, drugs, unsafe working conditions,
and poverty.
Case Study: Growing Germ
Resistance to Antibiotics
Rabidly producing infectious bacteria are
becoming genetically resistant to widely
used antibiotics due to:
Genetic resistance: Spread of bacteria around
the globe by humans, overuse of pesticides
which produce pesticide resistant insects that
carry bacteria.
Overuse of antibiotics: A 2000 study found that
half of the antibiotics used to treat humans were
prescribed unnecessarily.
Transmissible Disease
Pathway for infectious disease in humans.
Figure 18-4
Transmissible Disease
WHO estimates
that each year the
world’s seven
deadliest infections
kill 13.6 million
people – most of
them the poor in
developing
countries.
Figure 18-5
CHEMICAL HAZARDS
A toxic chemical can cause temporary or
permanent harm or death.
Mutagens are chemicals or forms of radiation
that cause or increase the frequency of
mutations in DNA.
Teratogens are chemicals that cause harm or
birth defects to a fetus or embryo.
Carcinogens are chemicals or types of
radiation that can cause or promote cancer.
Effects of Chemicals on the Immune,
Nervous, and Endocrine Systems
Long-term exposure to some chemicals at
low doses may disrupt the body’s:
Immune system: specialized cells and tissues
that protect the body against disease and
harmful substances.
Nervous system: brain, spinal cord, and
peripheral nerves.
Endocrine system: complex network of glands
that release minute amounts of hormones into
the bloodstream.
TOXICOLOGY: ASSESSING
CHEMICAL HAZARDS
Factors determining the harm caused by
exposure to a chemical include:
The amount of exposure (dose).
The frequency of exposure.
The person who is exposed.
The effectiveness of the body’s detoxification
systems.
One’s genetic makeup.
TOXICOLOGY: ASSESSING
CHEMICAL HAZARDS
Children are more susceptible to the effects
of toxic substances because:
Children breathe more air, drink more water,
and eat more food per unit of body weight than
adults.
They are exposed to toxins when they put their
fingers or other objects in their mouths.
Children usually have less well-developed
immune systems and detoxification processes
than adults.
RISK ANALYSIS
Annual deaths in the U.S. from tobacco
use and other causes in 2003.
Figure 18-A
RISK ANALYSIS
Number of deaths per year in the world from various
causes. Parentheses show deaths in terms of the number
of fully loaded 400-passenger jumbo jets crashing every
day of the year with no survivors.
Figure 18-13
Hazard
Poverty
Born male
Smoking
Overweight (35%)
Unmarried
Overweight (15%)
Spouse smoking
Driving
Air pollution
Alcohol
Drug abuse
Flu
AIDS
Drowning
Pesticides
Fire
Natural radiation
Medical X rays
Oral contraceptives
Toxic waste
Flying
Hurricanes, tornadoes
Lifetime near nuclear plant
Shortens average life span in the U.S. by
7–10 years
7.5 years
6–10 years
6 years
5 years
2 years
1 year
7 months
5 months
5 months
4 months
4 months
3 months
1 month
1 month
1 month
8 days
5 days
5 days
4 days
1 day
1 day
10 hours
Fig. 18-14, p. 436
HAZARDOUS WASTE
Hazardous waste: is any discarded solid or
liquid material that is toxic, ignitable,
corrosive, or reactive enough to explode or
release toxic fumes.
The two largest classes of hazardous wastes are
organic compounds (e.g. pesticides, PCBs,
dioxins) and toxic heavy metals (e.g. lead,
mercury, arsenic).
Hazardous Waste Regulations in the
United States
Two major federal laws regulate the management
and disposal of hazardous waste in the U.S.:
Resource Conservation and Recovery Act (RCRA)
• Cradle-to-the-grave system to keep track waste.
Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA)
• Commonly known as Superfund program - polluters pay fo
cleaning up abandoned hazardous waste sites
Conversion to Less Hazardous
Substances
Physical Methods: using charcoal or resins to
separate out harmful chemicals.
Chemical Methods: using chemical reactions that
can convert hazardous chemicals to less harmful
or harmless chemicals.
Conversion to Less Hazardous
Substances
Biological Methods:
Bioremediation: bacteria or enzymes help destroy or
convert toxic and hazardous waste
Phytoremediation: involves using natural or
genetically engineered plants to absorb, filter and
remove contaminants from polluted soil and water.
Radioactive
contaminants
Organic
contaminants
Sunflower
Willow tree
Inorganic
metal contaminants
Poplar tree
Brake fern
Indian mustard
Landfill
Polluted
groundwater in
Soil
Groundwater
Decontaminated
water out
Rhizofiltration
Roots of plants such as
Phytostabilization
sunflowers with dangling
Plants such as willow
trees
and poplars can
roots on ponds or in greenabsorb chemicals and
houses can absorb pollutants
keep them from reaching
such as radioactive strontium-90 groundwater or nearby
surface water.
and cesium-137 and various
organic chemicals.
Polluted
leachate
Oil
spill
Phytodegradation
Plants such as poplars
can absorb toxic organic
chemicals and break
them down into less
harmful compounds
which they store or
release slowly into the air.
Soil
Groundwater
Phytoextraction
Roots of plants such as Indian
mustard and brake ferns can
absorb toxic metals such as
lead, arsenic, and others and
store them in their leaves.
Plants can then be recycled
or harvested and incinerated.
Conversion to Less Hazardous
Substances
Incineration: heating many types of hazardous
waste to high temperatures – up to 2000 °C – in
an incinerator can break them down and convert
them to less harmful or harmless chemicals.
Long-Term Storage of Hazardous
Waste
Hazardous waste can be disposed of on or
underneath the earth’s surface, but without proper
design and care this can pollute the air and water.
Deep-well disposal: liquid hazardous wastes are
pumped under pressure into dry porous rock far
beneath aquifers.
Surface impoundments: excavated depressions such
as ponds, pits, or lagoons into which liners are placed
and liquid hazardous wastes are stored.
Long-Term Storage of Hazardous
Waste
Long-Term Retrievable Storage: Some highly
toxic materials cannot be detoxified or
destroyed. Metal drums are used to stored them
in areas that can be inspected and retrieved.
Secure Landfills: Sometimes hazardous waste
are put into drums and buried in carefully
designed and monitored sites.
Secure Hazardous Waste Landfill
In the U.S. there are
only 23 commercial
hazardous waste
landfills.
Figure 22-22