Download Name: Chapter 5: Water NOTES Section 5.3: Water Pollution Intro

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Chapter 5: Water
NOTES
Section 5.3: Water Pollution
Intro
 You cannot always determine if water is polluted by the way it looks or smells; there are different forms
of water pollution (chemical, physical or biological agents)
 The introduction of these agents can adversely affect the water quality and the organisms that depend on
the water
 There are two underlying causes of water pollution: industrialization and rapid human population
growth
 In the past 30 years, developed countries are making provisions to clean up polluted water supplies;
however, many sources continue to be dangerously polluted
 Water pollution continues to be a big problem in developing countries; industry is NOT the major cause
of pollution in those countries
 Available drinking water in these countries is polluted with sewage and agricultural runoff (spreading
waterborne diseases)
 People must understand where pollutants come from in order to prevent water pollution; comes from
two main sources: point and non-point
Point Pollution
• Pollution that is discharged from a single source (ex: factory, waste treatment plant, oil tanker)
• Relatively easy to regulate and control because it is easily identified and traced
• Hard to enforce clean-up
Nonpoint Pollution
• Comes from many sources rather than from a single specific site; reaches bodies of water via streets and
storm sewers (ex: homes, lawns, farms, highways, also from pesticides, fertilizers, animal feces)
• Extremely difficult to regulate and control
• Small amounts add up to a huge pollution problem; 96% of polluted bodies of water come from
nonpoint pollution contamination
• Public awareness and education will probably be the most effective way of reducing nonpoint pollution
Wastewater
• Water that goes down a drain ends up in a wastewater treatment plant
• Wastewater is water that contains waste from homes and industry
• At a wastewater treatment plant, the water is filtered and treated; then it is returned to a river or lake
Treating Wastewater
• Home wastewater is biodegradable and can be broken down by living organisms (ex: toilet and kitchen
wastewater contains animal and plant waste, paper and soap – all are biodegradable)
• However, some home, industrial and storm runoff may contain toxic substances that interfere with
treatment and cannot be removed by the standard treatment
Sewage Sludge
• By-product of wastewater treatment is sewage sludge ( solid materials that remains after treatment);
many contain toxic chemicals; incinerated and then buried
• Non-toxic sludge can be used as fertilizer (contain plant nutrients) if it is free of toxins; can be made into
bricks when combined with clay
Pathogens
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Disease causing organisms (bacteria, viruses, parasitic worms)
Can enter water supplies in untreated wastewater or animal feces
Cholera, hepatitis, typhoid are diseases people can get from drinking water containing these pathogens
Public water supplies are constantly monitored for the presence of these pathogens.
Artificial Eutrophication
• Most nutrients in water come from organic matter (leaves, animal waste); it is broken down into mineral
nutrients by decomposers (bacteria, fungi)
• An overabundance of nutrients can disrupt the ecosystem (eutrophic)
• Eutrophication is a natural process; however, the addition of inorganic plant nutrients from fertilizer
runoff and sewage (phosphorous and nitrogen, ex: laundry detergents, dishwashing soap, lawn
fertilizers) causes excessive growth of algae (algal blooms) which die and when they decompose use
large amounts of dissolved oxygen in the water; fish suffocate and die (artificial eutrophication)
• Some states are now banning phosphate detergents; others have limited the amount of phosphates in the
detergents