Water is uniquely vulnerable to pollution. Known as a “universal solvent,” water is able to dissolve more substances than any other liquid on earth. It’s the reason we have Kool-Aid and brilliant blue waterfalls. It’s also why water is so easily polluted. Toxic substances from farms, towns, and factories readily dissolve into and mix with it, causing water pollution.

1. WATER POLLUTION –Part 1

2. WATER POLLUTION: SOURCES,
TYPES, AND EFFECTS
• 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.
– 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)

3. WATER POLLUTION: SOURCES,
TYPES, AND EFFECTS
• Major sources of water pollution:
– Agriculture
• Sediment, fertilizer, pesticides, bacteria
– Industries
• Organic and inorganic chemicals
– Mining
• Eroded sediments and runoff of toxic chemicals

4. Types of Pollutants
• Disease-causing agents (infectious
agents)
– Pathogens that cause disease
– Ex. bacteria, viruses, protozoa, and parasitic
worms
– Source: human and animal wastes

5. Table 21-2, p. 495

6. 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

7. Types of Pollutants cont.
• Water-soluble inorganic chemicals,
– Examples are acids, salts, and compounds of
toxic metals (lead and arsenic)
– Affected water is unfit to drink and is harmful to
aquatic life.
– Damages nervous system, liver, kidneys, skin
cancer.

8. Types of Pollutants cont.
• Inorganic Plant Nutrients
– Examples include water-soluble nitrates and
phosphates
– Causes overgrowth of algae which leads to
the depletion of dissolved oxygen and the
death of fish
– Sources- runoff from fertilizers, manure

9. Types of Pollutants cont.
• Organic chemicals
• Examples include gasoline, oil, plastics, pesticides,
cleaning solvents, detergents, medicines
• Threaten human and aquatic life; impacts nervous
system. Can cause cancer in humans.

10. Types of Pollutants cont.
• Sediment/ Suspended Matter
– Biggest class
– Examples include insoluble particles of soil
and other solids released by erosion.
– Sediments cloud water and disrupt aquatic
food webs.

11. Types of Pollutants cont.
• Thermal pollution
– Caused by the heat absorbed by the water used to
cool nuclear power plants. This water is returned
to natural environment warm.
– Lowers dissolved oxygen levels
– Causes an abrupt change in temperature- thermal
shock.

12. POLLUTION OF FRESHWATER
STREAMS
• Most more-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 less-
developed countries.