Download Testing Water for Pollutants

Brodnax
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Water pollution
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Any chemical, biological, or physical change in water quality
that harms living organisms or makes water unsuitable for
desired uses.
Point sources
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Why care about water Video
Located at specific places
Easy to identify, monitor, and regulate
Examples:
• Ditches, sewer lines, drain pipes, oil tankers,
underground mines
Nonpoint sources
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Broad, diffuse areas from which pollutants enter bodies of
surface water or air
Difficult to identify and control
Expensive to clean up
Examples
• Runoff (chemical or biological) from feedlots,
cropland, lawns, golf courses, logged forests, urban
streets & parking lots (THINK BIG AREA)
Point Source of Polluted Water
in Gargas, France
BIGGEST Sources of Water Pollution
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Agriculture activities
• ***Sediment eroded from agricultural land***
• Fertilizers and pesticides
• Bacteria from livestock and food processing wastes
Industrial facilities
• Organic and inorganic chemicals
Mining
• Sediment from eroding soil
• Toxic chemicals
Nonpoint Sediment from Unprotected
Farmland Flows into Streams
Other Sources of Water Pollution
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Other sources of water pollution
• Parking lots
• Build-up of toxins on surface
• Human-made materials
• Ex.: plastics – release polymers as they break down
• Climate change due to global warming
• will affect precipitation and change amounts of
pollutants washing into the hydrological cycle
Types of Water Pollution Video
Parking lot pollutants will make their
way into our water supply
Major Water Pollutants have Harmful Effects
 Over 500 disease-causing agents can be spread through water
vectors
 According to The World Health Organization (WHO):
• 3.2 Million people die every year from water diseases or
clean water shortages (most under 5)
• In the developing world, diarrheal diseases kill a
child under 5 every 18 SECONDS
• 1.2 Billion people (1 out of 6) worldwide have no access to
clean drinking water
Water Quality
There are 3 indicators of water quality: the concentrations of
dissolved oxygen (DO), the biological oxygen demand (BOD), and
the coliform bacteria count.
 Dissolved Oxygen (DO): the amount of oxygen gas
dissolved in water.
o At 68°F (20°C) and normal atmospheric pressure,
the maximum DO level is 9 ppm (parts per
million) and is healthy.
o DO level is an important indication of the
ecological health of a waterway.
o If the DO level drops below 4.5 ppm, fish
populations decline rapidly.
o Can indicate the presence of oxygen demanding
bacteria – a sign that the water is polluted by
potentially disease causing agents
Water Testing Video
 Biological Oxygen Demand (BOD): amount of
dissolved oxygen gas required for bacterial
decomposition of organic wastes in water.
o Bacterial decomposition may reduce the BO
content so much that some aquatic organisms
die.
o Water is seriously polluted when the BOD of
the decomposers cause the DO to fall below 5
ppm.
 Coliform Bacteria: Escherichia coli are intestinal
microbes found in soils and feces of humans and
other animals.
o Their presence indicates that other harmful
microbes (that cause diseases such as viral
hepatitis, cholera, dysentery, or encephalitis)
may also be present
o Bacteria can be grown in laboratories and
counted
o At a site where untreated sewage is dumped
in a stream, bacteria start feasting on the
sewage and the BOD increases enormously.
Downstream, the DO levels drop drastically
and fish die. Fish do not die from the sewage
directly, rather from the lack of oxygen.
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Indicator species
• Scientists can remove cattails from
contaminated areas and test them for
specific pollutants
• Mussels can also be tested for pollutants
since they are bottom-dwellers that filter the
water with their bodies
Genetic engineering
• Scientists are creating bacteria and yeast
that glow in the presence of a particular toxic
chemical, like heavy metals or carcinogens.
Measuring sediment
• Scientists measure sediment amounts and
analyze the water for color and turbidity
• Turbidity – cloudiness of the water
BOD (ppm)
Pure water
Typical fresh,
natural water
Domestic sewage
Sewage after
treatment
0
2-5
Hundreds
10-20
Chemical analysis of
Fecal Coliform (per 100 mL)
Testing Water for Pollutants
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Type of Water
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For drinking = NO colonies
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For swimming < 200 colonies
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Raw sewage contains several
million colonies
Streams can cleanse themselves if we do
not overload them
 Flowing rivers and streams can recover rapidly
from moderate levels of degradable wastes
through a combination of dilution and
biodegradation of such wastes by bacteria.
Chemical tests
used in
measuring
water quality:
phosphates,
nitrates, pH,
salinity, etc.
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This process is hindered by excessive
amounts of pollutants, drought,
damming, or water diversions that
reduce their flows
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This process cannot remove slowly
degradable (like DDT) and
nondegradable pollutants (like lead and
arsenic)
Global Outlook
 Half of the world’s 500 rivers are polluted
o Most of these are in developing countries
 Cannot afford waste treatment
 Cannot enforce water pollution laws
 Untreated sewage
o Developing countries dump 80-90% of waste
raw
 Industrial waste
o Pollutes 2/3 of India’s rivers
 China’s rivers
o 1/3 unsafe for agricultural & industrial use
o 300 million people without access to potable
(drinkable) H20
Water pollution in India Video
Lakes are more vulnerable to
pollution
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Lakes are less effective at diluting
pollutants than streams
o Stratified layers
 Little vertical mixing
o Little or no water flow
Trash truck dumping garbage into river in
Peru
Eutrophication of Lakes
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Oligotrophic lake
• Low nutrients, clear water
• Supports little plant life and fish species such as
trout and small mouth bass
• High DO levels
Eutrophic lake
• Nutrient-rich lake
• Supports a great deal of plant life, which often chokes
out other organisms
• Low DO content
• Large algae populations, and fish species such as
carp and bullhead
Eutrophication
• Natural nutrient enrichment of a lake over time
Cultural eutrophication
• Accelerated nutrient enrichment due to human
activities involving mostly nitrate and phosphate
containing effluents
 Sources: feedlots, farmland, suburban yards,
mining sites, untreated sewage
Cultural Eutrophication Video
Oligotrophic Lake
Eutrophic Lake