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Water Pollution
Part I
Sources - General
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Point Source: when a harmful substance
is released directly into a body of water
Usually monitored and regulated in
developing countries
 Ex: industrial discharge into a river
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Non-point source: deliver pollutants
through transport or environmental
change
Indirect and more difficult to monitor and
control
 Ex: fertilized from a farmers feild
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Sources - Air pollution:
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mercury, sulfur dioxide, nitric oxides, and
ammonia fall out of the air and into bodies
of water
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Cause: Acidification, eutrophication and
contamination of fish
Sources – Methyl Mercury
Inorganic mercury enters water systems
and is converted to methyl mercury by
bacteria
 Enters food chain and bioaccumulates
 Humans exposed by eating
contaminated fish
 Methyl mercury is more toxic than
inorganic mercury
 Organisms take a long time to process
out methyl mercury
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Sources – Other chemicals
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Variety of chemicals
Bioaccumulate and poison fish, marine
mammals, birds, and humans
Affect the development and reproduction of
various marine animals
Examples:
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Metals
Solvents
Oils
Detergents
Pesticides
Prescription drugs
●Hormones
●Antibiotics
●Personal care products
●Household products
Sources - Microbial

Pathogenic (disease-causing)
microorganisms (bacteria, viruses,
protozoa)
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Infects drinking sources when raw
sewage is dumped into rivers, lakes, and
bays
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Ex: cholera, typhoid, polio, meningitis,
hepatitis, “Montezuma's revenge”
90% of sewage in developing world is raw
Leaking septic tanks and other sources
contaminate groundwater and streams
Sources - Mining
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Methods of contamination:
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Exposes heavy metals and sulfur compounds
that can leach out of rock and into water
sources
Rainwater washes chemicals out of mining
waste and into water sources
Pools of mining waste leak and contaminate
ground water
Direct dumping of mining waste into rivers
Examples:
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2003 – US reclassified mining waste from
mountain top removal so it could be dumped in
valleys
Iron Mountain mine in CA – closed in 1963, still
drains sulfuric acid and heavy metals into the
Sacramento river
Sources - Noise

Commercial shipping, military sonar,
recreational boating create noise that
interferes with marine organisms who
use sound to communicate, navigate,
and hunt
Sources - Nutrients
Phosphorus and Nitrogen from
fertilizers cause algal blooms
 Damages rivers, lakes, oceans,
estuaries, and deltas
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Sources – Oil Spills
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From ship and well leaks and spills
Effects:
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Coats sea birds making them more vulnerable
to temperature fluctuations and poisons them
when they clean themselves
Poisons food sources and leads to
bioaccumulation
Limits photosynthesis
Clean up:
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Use microorganisms to “eat oil”
Use chemical agents to try to control oil for
clean up
Controlled burning, skimming, booming,
vacuuming oil from surface and shorelines
Sources – Oxygen-depleting
Substances
Biodegradable wastes serve as food
for microorganisms which take oxygen
out of the water
 Results in:
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Anoxic water and fish kills
 Increased activity from anaerobic
bacteria which produce ammonia,
amines, sulfides, methane
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Source - Plastic
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From litter that enters watersheds
Problems:
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Plastic photodegrades into smaller pieces
Leach chemical toxins into environment
Consumed by marine animals and clogs their
digestive tracks
Gets caught on animals
Spread invasive species
Absorb toxins and then leach them into upper
water column
Makes it more difficult for animals to see and
capture real food
Affect 250+ species world wide
Sources – Suspended
Matter
Suspended waste settles out and
contaminates mud at the bottom of
rivers affecting organisms throughout
the food web
 Can include, silt, plastics, other forms
of trash
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Sources - Thermal
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Produced by industry
Reduces the ability of water to hold oxygen
Causes death of animals with low tolerance to
heat and low oxygen conditions
Can change species composition of the area
Case Study - Minamata
disease
Between 1932 and 1968, 27 tons of
mercury- containing chemicals were
dumped into Minamata Bay, Japan
 Mercury accumulate in fish and
shellfish caught in the bay
 Disease symptoms (mercury
poisoning): blurred vision, hearing
loss, loss of muscular coordination,
reproductive disorders
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Case Studies – Oil Spills
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Exxon Valdez (1989):
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Oil tanker ran aground
Dumped 11 – 30 million gallons in Prince
William Sound, Alaska
Destroyed the habitat from plankton on up
Deepwater Horizon (2010):
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Following an explosion on the Deepwater
Horizon, well spilled oil into Gulf of Mexico for
months
Most significant environmental disaster in the
US
Oil followed currents, contaminated the Gulf
Coast
Damage to fishing, tourism, and other industries
Environmental damage to many habitats