Download 2. Non-point Source Pollution

Chapter 21
Water Pollution
Types of Water Pollution
Water pollution


Any physical or chemical change in water
that adversely affects the health of humans
and other organisms
1.
Sewage
2.
disease-causing agents
3.
sediment pollution
4.
inorganic plant and algal nutrients
5.
organic compounds
6.
inorganic chemicals
7.
radioactive substances
8.
thermal pollution
1. Sewage

Causes 2 serious environmental problems:
1. Enrichment

Fertilization of water by high levels N and P
2. Increase in Biological Oxygen Demand
(BOD)


BOD-amount of oxygen needed by microorganisms
to decompose biological wastes
BOD Dissolved Oxygen (DO)
Sewage
Sewage: Eutrophication

Oligotrophic

Unenriched, clear water that supports small populations
of aquatic organisms
Sewage: Eutrophication

Eutrophic

Slow-flowing stream, lake or estuary enriched by
inorganic plant and algal nutrients such as phosphorus
2. Disease-causing Agents

Infectious organisms
that cause diseases


from wastes of infected
individuals
Examples:

Typhoid, cholera,
bacterial dysentery,
polio, and infectious
hepatitis
India

3. Sediment Pollution
Excessive amounts of suspended soil
particles. From:

erosion of agricultural
lands
logging
degraded stream banks
overgrazing
mining

construction




4. Inorganic Plant and Algal
Nutrients


Ex: N and P
Sources:


Human and animal wastes, plant residues,
atmospheric deposition, and fertilizer runoff
It Causes:

Enrichment, bad odors, and a high BOD
Inorganic Plant and Algal
Nutrients: The Dead Zone
Hypoxia
5. Organic Compounds

Chemicals that contain carbon atoms
Dangerous!


Natural examples: sugars, amino acids, and
oils
Human-made examples: pesticides, solvents,
industrial chemicals, and plastics, medication
Volatile Organic Compounds in
Groundwater
Los Angeles
Seal Beach, CA
Depicts 60,000 plastic bags, the number used in the US every five seconds.
2 million bottles the number used by Americans every 5 minutes!
6. Inorganic Chemicals



Contaminants that contain elements other
than carbon (ex: acids, salts, heavy metals)
Do not degrade easily
Examples:


LeadMercury-
7. Radioactive Substances


Unstable isotopes that emit radiation
Sources:




Mining
Processing radioactive materials
Nuclear power plants
Natural sources
8. Thermal Pollution

Factories release heated water into
waterways

Why is this bad?


Temperature affects
reproductive cycles,
digestion rates, and
respiration rates
Warm water holds less
DO than cold water
Two Types of Water Pollution
1. Point Source Pollution

Water pollution that can be traced to a
specific origin
2. Non-point Source Pollution

Pollutants that enter bodies of water over
large areas rather than being concentrated at
a single point of entry
Water Pollution from Agriculture

Agriculture is leading source of water
pollution in US



Animal wastes and plants residues have high
BOD
Chemical pesticides
Almost all streams and rivers are polluted
with agricultural pesticides
Important*
There is little regulation!
Municipal Water Pollution
Industrial Wastes in Water

Different industries generate different
pollutants



Food processing plants- high BOD
Paper mills- High BOD and toxic compounds
Green Chemistry
Groundwater Pollution
Water Pollution in Other Countries



Lake Maracaibo, Venezuela
Po River, Italy
Ganges River, India
Purification of Drinking Water

In US most municipal water supplies are
treated
Purification of Drinking Water

Treated water distributed to customers
Purification of Drinking Water

Chlorine Dilemma



Chlorine byproducts are linked to numerous
cancers, miscarriages and birth defects
Peru
Fluoridation


Prevents tooth decay
Linked to cancer, kidney disease
Municipal Sewage Treatment
Laws Controlling Water Pollution

Safe Drinking Water Act (1974)


Set uniform federal standards for drinking
water including maximum contaminant level
Clean Water Act (1972)


EPA sets up and monitors National Emissions
Limitations
Effectively improved water quality from point
sources