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Lecture Presentation
Chapter 16
Protecting Water
and Air Resources
Bradley Sieve
Northern Kentucky University
Highland Heights, KY
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16.1 Water on the Move
• Hydrological Cycle
– Constant moving and changing of phases
of water
– Water table is the top of the saturation level
in soil
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16.1 Water on the Move
• Lakes and streams are regions where the
water table lies above the land surface
• Aquifers are underground water reservoirs
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16.1 Water on the Move
• As water is removed from the soil, ground
surface is lowered or subsides
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Concept Check
An aquifer is a body of underground fresh
water. Where does this water come from?
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Concept Check
The source of all natural underground (and
aboveground) fresh water is the atmosphere,
which gets most of its moisture from the
evaporation of ocean water.
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16.2 Collectively, We Consume Huge
Amounts of Water
• Huge amounts of water are consumed
each day
– USGS data state that 6790 billion liters/day
enter aquifers
– We remove 1319 billion liters/day, about 20%
– In dryer regions, our use outpaces the daily
intake of water
– Per person, that is 4380 liters/day in the
United States
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16.2 Collectively, We Consume Huge
Amounts of Water
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16.2 Collectively, We Consume Huge
Amounts of Water
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16.3 Human Activities Can Pollute Water
• Water pollution can be one of two types
– Point source—one specific, well-defined
location where pollution enters the water
– Nonpoint source—pollutants originate at
diverse locations
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16.3 Human Activities Can Pollute Water
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16.3 Human Activities Can Pollute Water
• Cleaning of Polluted Water
– Pollutants in rivers and lakes can be cleaned
because pollution is localized
– Groundwater pollution is more difficult to clean
• Groundwater is inaccessible
• Slow flow rate on water in the aquifers
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16.3 Human Activities Can Pollute Water
• Sources of Groundwater Pollution
– Solid-waste disposal sites
• Leachate—mixture of rainwater and chemicals
from the solid waste
– Sewage
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Concept Check
What is the difference between a point
source and a nonpoint source of pollution?
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Concept Check
A point source arises from a specific
location—you can pinpoint it on a map. A
nonpoint source represents a collection of
many sources, each difficult to trace. To
specify a nonpoint source on a map, you
need to draw a circle.
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16.3 Human Activities Can Pollute Water
• Organisms exist in natural water sources
– Aerobic bacteria
• Bacteria that decompose organic matter in the
presence of oxygen
• Utilize oxygen in water, forming CO2, H2O, NO3–,
and SO42–
• Products are odorless and cause little harm
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16.3 Human Activities Can Pollute Water
• Organisms exist in natural water sources
– Anaerobic bacteria
• Bacteria that decompose organic matter in the
absence of oxygen
• Produce dangerous and unpleasant products when
decomposing materials
• Products include methane (CH4), amines (such as
NH2C4H8NH2), and sulfur compounds (such as H2S)
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16.3 Human Activities Can Pollute Water
• Biochemical Oxygen Demand (BOD)
– Amount of dissolved oxygen needed for aerobic
bacteria to decompose organic matter
– If amount of dissolved oxygen is lower than BOD
• Organisms start to die off
• Anaerobic bacteria begin to take over
breakdown of organic materials
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16.3 Human Activities Can Pollute Water
• Algae Bloom
– Rapid growth of algae and aquatic plants
– The plants consume more oxygen than they
produce, depleting overall oxygen level
– Covers the surface of the water, reducing
oxygen absorption from the air
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16.4 Wastewater Treatment
• Wastewater must be treated before it is
released into bodies of water
– Completed at water treatment centers
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16.4 Wastewater Treatment
• Primary-Level Wastewater Treatment
1) Screening of solid waste
2) Primary treatment where suspended solids
settle out as sludge
3) Disinfection with either chlorine gas or ozone
• After primary-level treatment, waste often
passes through secondary and tertiary
levels of treatment
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16.4 Wastewater Treatment
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Concept Check
Distinguish among the main functions of
primary, secondary, and tertiary wastewater
treatment.
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Concept Check
Primary wastewater treatment removes the bulk of
solid waste and sludge from the sewage effluent
using screening devices and large settling basins.
Secondary treatment provides oxygen to oxygendependent bacteria that serve to decompose organic
matter. Tertiary treatment removes pathogens and
wastes not removed by earlier treatments by filtering
the effluent through beds of powdered carbon or
other fine particles.
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16.5 The Earth’s Atmosphere Is a Mixture
of Gases
• Air molecules interact with energy from the
Sun and gravity to make our atmosphere
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16.5 The Earth’s Atmosphere Is a Mixture
of Gases
• Atmosphere
– Layer of air 50 km thick around the Earth
– Provides oxygen, nitrogen, carbon dioxide,
and other gases to living things
– Protects from cosmic radiation and debris
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16.5 The Earth’s Atmosphere Is a Mixture
of Gases
• Effects of Elevation
– Atmospheric pressure
• Pressure of air on objects submerged into
the atmosphere
• Pressure is higher at sea level than at
elevated mountaintops
– Temperature changes
• Lower elevations are generally warmer due
to the Earth’s surface radiating heat
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16.5 The Earth’s Atmosphere Is a Mixture
of Gases
• Layers of the Atmosphere
– Troposphere—lowest level of the atmosphere
– Stratosphere—portion of the atmosphere
above the troposphere
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16.5 The Earth’s Atmosphere Is a Mixture
of Gases
• Troposhere
– Lowest level of the atmosphere
– Contains 90% of atmospheric mass
– Contains essentially all of the water vapor
and clouds
– Where weather occurs
– Extends up to about 16 km in height
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16.5 The Earth’s Atmosphere Is a Mixture
of Gases
• Stratosphere
– Reaches a height of 50 km
– Contains the ozone layer at 20–30 km
– Lower regions are cooler than the upper
regions
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Concept Check
What effect does the Earth’s gravity have on
the atmosphere?
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Concept Check
The Earth’s gravity pulls molecules in the
atmosphere downward, preventing them
from escaping into outer space.
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16.6 Human Activities Have Increased Air
Pollution
• Air Pollutant
– Material in the atmosphere that is harmful
to health
– Sources include natural and man-made
sources
– Clean Air Act restricts air pollutants
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16.6 Human Activities Have Increased Air
Pollution
• Airborne Solid Particles
– Ash, soot, metal oxides, and sea salts
– Aerosols
• Particles merged with water droplets, which
facilitate reactions
• Suspended in air for extended durations
– Particulates
• Larger particles that settle to the ground
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16.6 Human Activities Have Increased Air
Pollution
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16.6 Human Activities Have Increased Air
Pollution
• Smog
– A poisonous mixture of smoke, fog, and air
– Occurs when a temperature inversion occurs
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Concept Check
Why are temperature inversions more
common during the day than at night?
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Concept Check
A temperature inversion occurs when a body
of warm air sits above a body of denser cold
air. The higher air is warmed by the heat of
the Sun, which is out only during the day.
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16.6 Human Activities Have Increased Air
Pollution
• Two Types of Smog
– Industrial
• Smog that is high in particulates
• Main component is sulfur dioxide
– Photochemical smog
• Contains particulates that participate in
sunlight-induced chemical reaction
• Contains chemicals such as NO2, HNO3,
and ozone
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16.6 Human Activities Have Increased Air
Pollution
• Hydrocarbons are another class of
components in photochemical smog
– Transformed to aldehydes and ketones, adding
a foul odor
– Often released when gas tanks are filled
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Concept Check
How does the Sun help disperse air
pollutants?
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Concept Check
Sunlight warms the ground, which in turn
warms the air, which then rises, carrying
with it many air pollutants.
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16.7 Carbon Dioxide Helps Keep the
Earth Warm
• Glass is transparent to visible light but not
to infrared light
– Leads to the greenhouse effect and warming
of the interior
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16.7 Carbon Dioxide Helps Keep the
Earth Warm
• Greenhouse Gases
– Include carbon dioxide, water vapor, and
other gases
– Work in the same manner as glass to enclose
and trap heat
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Concept Check
What does it mean to say that the greenhouse
effect is like a one-way valve?
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Concept Check
Both the Earth’s atmosphere and glass allow
incoming visible waves, but not outgoing
infrared waves, to pass. As a result, radiant
energy is trapped.
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16.7 Carbon Dioxide Helps Keep the
Earth Warm
• Carbon Dioxide
– Has a well-documented history as a
greenhouse gas
– Core samples show a close relationship
between CO2 and global temperatures
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16.7 Carbon Dioxide Helps Keep the
Earth Warm
• Carbon dioxide levels have increased
since the Industrial Revolution
– Increased CO2 levels correspond to increased
average temperatures
– CO2 is currently the number-one gas emitted
by human activities
– 158 billion tons have been added since 1958
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16.7 Carbon Dioxide Helps Keep the
Earth Warm
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16.7 Carbon Dioxide Helps Keep the
Earth Warm
• Modern Sources of CO2
– Burning of fossil fuels releases CO2 as the
energy is released
– Deforestation
• Removes the CO2 sink of the growing
vegetation
• Releases additional CO2 if the material
is burned
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16.7 Carbon Dioxide Helps Keep the
Earth Warm
• Potential effects of global climate change
are uncertain
– Consensus is that increasing greenhouse
gases will result in global warming
– Many questions still remain due to the large
number of variables
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Concept Check
Why are scientists uncertain about the
potential effects of global warming?
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Concept Check
The uncertainty is due to the large number
of variables that determines global weather
patterns. As the debates continue, bear in
mind that the issue is not global warming
itself, but rather its potential effects.
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