Water Pollution

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Water Pollution

• Chapter 20

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20-1 What Are the Causes and Effects of Water
Pollution?

• Concept 20-1A Water pollution causes illness and
  death in humans and other species and disrupts
  ecosystems.
• Concept 20-1B The chief sources of water
  pollution are agricultural activities, industrial
  facilities, and mining, but growth in population
  and resource use make it increasingly worse.

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Water Pollution Comes from Point and Nonpoint
Sources

• Water pollution is any chemical, biological, or
  physical change in water quality that has a
  harmful effect on living organisms or makes water
  unsuitable for desired uses.
• Water quality, or its chemical and physical
  makeup, depends upon its intended use.
• Drinking water needs to be as pure H2O and
  possible
• Water used for washing your car or watering your
  lawn can be of lower quality

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Water Pollution Comes from Point and Nonpoint
Sources

• Point source specific location or from a single
  point
• Drain pipes, ditches, sewer lines, spills
• Fairly easy to identify, monitor, and regulate
• Nonpoint source cannot be traced to a single
  site of discharge
• Atmospheric deposition, runoff from agricultural
  / industrial / residential lands
• Difficult to identify and control and expensive
  to clean up because of the many diffuse sources

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Water Pollution Comes from Point and Nonpoint
Sources

• Major sources of water pollution are
• Agricultural activities are by far the leading
  cause of water pollution.
• Sediment eroded from agricultural lands,
  fertilizers, pesticides, bacteria from livestock,
  salts from irrigation
• Industrial facilities release a variety of
  harmful organic and inorganic chemicals.
• Surface mining disturbs the Earths surface
  causing runoff of sediments and toxic chemicals.

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Major Water Pollutants and Their Sources
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Science FocusTesting Water for Pollutants

• There are a variety of tests to determine water
  quality
• Temperature
• pH
• Dissolved Oxygen
• Total Dissolved Solids
• Flow Rate
• Phosphates
• Nitrates
• Chlorides
• Color and turbidity of the water
• Coliform bacteria E. coli
• Biological Assessment
• Indicator species

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20-2 What Are the Major Water Pollution Problems
in Streams and Lakes?

• Concept 20-2A While streams are extensively
  polluted worldwide by human activities, they can
  cleanse themselves of many pollutants if we do
  not overload them or reduce their flows.
• Concept 20-2B Addition of excessive nutrients to
  lakes from human activities can disrupt lake
  ecosystems, and prevention of such pollution is
  more effective and less costly than cleaning it
  up.

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Streams Can Cleanse Themselves If We Do Not
Overload Them

• Flowing streams can recover from a moderate level
  of water pollution if they are not overloaded
  with pollutants and their flows are not reduced.
• In a flowing stream, the breakdown of degradable
  wastes by bacteria depletes dissolved oxygen and
  creates an oxygen sag curve.
• Biodegradation of wastes by bacteria takes time
• This reduces or eliminates populations of
  organisms that require high amounts of oxygen
  until the stream is cleansed of wastes.

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Dilution and Decay of Degradable,
Oxygen-Demanding Wastes in a Stream

• Similar oxygen sag curves can result from thermal
  pollution.

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Stream Pollution in Developed Countries

• Most developed countries have sharply reduced
  point-source pollution but water contamination is
  still a problem.
• Accidental or deliberate releases of toxic
  chemicals by industries, mines, malfunctioning
  sewage treatment plants
• Non-point runoff of pesticides and nutrients from
  cropland and livestock

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Stream Pollution in Developing Countries

• Stream pollution in most developing countries is
  a major problem.
• Untreated sewage, infectious agents, industrial
  wastes
• Most countries cannot afford water treatment
  plants.
• Many dont have water quality laws or the laws
  are not enforced.

• Problems are made worse by the fact that many
  people in developing countries drink, bath, and
  wash clothes in rivers.

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Case Study Indias Ganges River Religion,
Poverty, Population Growth, and Health

• Daily, more than 1 million Hindus in India bathe,
  drink from, or carry out religious ceremonies in
  the highly polluted Ganges River.

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Case Study Indias Ganges River Religion,
Poverty, Population Growth, 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
• Animal wastes and carcasses are thrown into river
• 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

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Low Water Flow and Too Little Mixing Makes Lakes
Vulnerable to Water Pollution

• 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 layered by
  temperature and undergo little mixing
• Low flow makes them susceptible to runoff
• Rivers can be flushed of pollutants in days,
  compared to the years it would take to be removed
  from a lake.
• Various human activities can overload lakes with
  plant nutrients, which decrease DO and kill some
  aquatic species.

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Cultural Eutrophication Is Too Much of a Good
Thing

• Eutrophication natural nutrient enrichment of a
  shallow lake, estuary or slow moving stream,
  mostly from the runoff of plant nutrients from
  the surrounding land.
• The opposite Oligotrophic lake
• Low nutrients, clear water
• Cultural eutrophication when human activities
  accelerate the input of plant nutrients (mostly
  nitrates and phosphates) to a lake.
• 85 of large lakes near major population centers
  in the U.S. have some degree of cultural
  eutrophication.

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Cultural Eutrophication Is Too Much of a Good
Thing

• Eutrophication can lead to a large fish kill
  events.
• Excessive nutrients cause out of control algae
  growth
• Algae use up all the nutrients, die, and
  decompose
• The decomposition process results in low oxygen
  levels and an oxygen sag is created
• 1000s or 10,000s of fish can be killed at a time

• In Iowa, fish kills are caused by large amounts
  of manure being spilled into rivers, streams,
  lakes

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20-3 Pollution Problems Affecting Groundwater,
Other Water Sources

• Concept 20-3A Chemicals used in agriculture,
  industry, transportation, and homes can spill and
  leak into groundwater and make it undrinkable.
• Concept 20-3B There are simple ways and complex
  ways to purify drinking water, but protecting it
  through pollution prevention is the least
  expensive and most effective strategy.

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Ground Water Cannot Cleanse Itself Very Well

• The drinking water for about half of the U.S.
  population and 95 of those in rural areas comes
  from groundwater.
• Common groundwater pollutants are gasoline,
  fertilizers, pesticides, and organic solvents
• Sources spills, leaking underground pipes and
  tanks, seepage down from the surface
• Once a pollutant contaminates groundwater, it
  fills the pores between the sediment particles
  like a sponge
• This makes removal and cleanup very difficult and
  costly

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Principal Sources of Groundwater Contamination in
the U.S.
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Ground Water Cannot Cleanse Itself Very Well

• When groundwater pollutants reach an aquifer,
  they spread out and form a specific shape called
  a plume.

Direction of water flow
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Ground Water Cannot Cleanse Itself Very Well

• Groundwater can become contaminated with a
  variety of chemicals because it cannot
  effectively cleanse itself or dilute and disperse
  pollutants.
• Slow flow contaminants not diluted
• Less dissolved oxygen less decomposition
• Fewer decomposing bacteria
• Colder temperatures slow down chemical reactions
• As a result, it can take 100s to 1000s of years
  for contaminated groundwater to cleanse itself of
  degradable wastes.
• Non-degradable wastes (toxic lead, arsenic,
  flouride) are there permanently.

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Solutions Groundwater Pollution, Prevention
and Cleanup

• Groundwater contamination is the most clear
  situation where prevention is the only true
  solution.
• All cleanup methods are expensive and time
  consuming

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There Are Many Ways to Purify Drinking Water

• Centralized water treatment plants
  and watershed protection can
  provide safe drinking water for
  cities in developed
  countries.
• Simpler and cheaper ways can be used to purify
  drinking water for developing countries.
• Boiling water or exposure to the
  suns UV rays for 3 hours can
  kill infectious
  microbes.
• While most developed countries have drinking
  water quality standards and laws, most developing
  countries do not.

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Using Laws to Protect Drinking Water Quality

• The U.S. Safe Drinking Water Act requires the EPA
  to establish national drinking water standards
  (maximum contaminant levels) for any pollutant
  that may have adverse effects on human health.

• Originally, it only focused on standards for
  water treatment
• Now, it includes protections for drinking water
  sources as well
• rivers, lakes, springs, groundwater

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Using Laws to Protect Drinking Water Quality

• The U.N. estimates that 5.6 million Americans
  drink water that does not meet EPA standards.
• 1 in 5 Americans drinks water from a treatment
  plant that violated one or more safety standard.
• Industry pressures to weaken the Safe Drinking
  Act
• Eliminate national tests and public notification
  of violations
• Allow rights to pollute if provider cannot afford
  to comply
• Reduce EPAs budget which limits its ability to
  monitor and enforce water quality standards

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Is Bottled Water the Answer?

• NO!!

• ¼ of bottled water is just tap water
• 40 of bottled water is lower quality than tap
  water and costs much more.
• Fossil fuels are used to make plastic bottles.
• The oil used to produce plastic bottles in the
  U.S. each year would fuel 100,000 cars.
• 1.4 million metric tons of plastic bottles are
  thrown away.