Water PollutionChapter 18
What is Water Pollution?
Water pollution is anything that degrades water quality!
Pollution is spread from:
Point sources: Sources of pollution that come from specific locations (drain pipes, sewer outfalls, ditches)
Nonpoint sources: Sources of pollution that are scattered or diffuse such as runoff from farm fields.
Water Pollution
Infectious agents, organic and inorganic chemicals from industrial effluents, natural sources of radioactive materials all effect human health
Sediment from erosion, plant nutrients from fertilizers and sewage, thermal pollution from power plant and industrial cooling are all reasons of ecosystem disruption.
Water Pollution con’t
Bacterial diseases are found in many water sources mainly in poorer countries.
Sediments can also be found in water and can greatly degrade water quality.
The amount of oxygen dissolved in water is used as an indicator of its quality (page 407)
Biochemical oxygen demand (BOD): test measuring the amount of dissolved oxygen in water
Water Pollution Control
Source reduction is often the cheapest and best way to reduce pollution. (avoid producing pollution to reduce it).
In order to control nonpoint sources, land contaminating agriculture, urban runoff, construction, and waste disposal must be managed and regulated
Effluent sewage: a tank collects and digests solid waste. Liquid waste is filtered into a central treatment plant.
Water Pollution Control cont
Wetlands: after 20-30 days of exposure to sun, air, and aquatic plants, pathogens in the polluted water are destroyed. Effluent is used for crop irrigation or to raise fish for human consumption
Municipal sewage treatment:
Primary treatment: separates large solids from waste and filters liquid through a screen. The effluent is not yet safe to discharge
Secondary treatment: effluent from primary treatment moves to a sewage lagoon where it aerobically decomposes
Water Quality Today
Due to The Clean Water Act only 10% of water pollution in the US is due to industrial waste.
However, the Act only protects “navigable” water sources, so areas such as wetlands are excluded and are not protected by the act.
Around 117 million Americans get their drinking water from sources that are not protected by the clean water act.
Water Quality Today cont
Although some countries, such as Sweden, serve water that receives sewage treatment twice, many countries are served water that isn’t treated at all.
In Greece, only 1% of water served is even treated once prior to distribution.
There is little control on ocean pollution throughout the world.
Water Legislation
Federal Water Pollution Control Act (1972): nationwide controls for major polluting industries
Clean Water Act (1985): point sources of pollution were required to have discharge permits and best possible control technology. Set national goal for all surface waters to be “fishable and swimmable”
Safe Drinking Water Act (1974): regulates water quality in commercial and municipal systems.
What Can You Do?
Compost yard and pet waste Don’t fertilize lawn or apply lawn chemicals Make sure your car doesn’t leak fluids Create a “rain garden” to capture and filter surface
runoff Avoid buying two-cycle engines (i.e. lawnmowers,
snowmobiles) Keep informed about water policy debates at local
and federal levels. Input is important!!
Fun Facts
The World Bank estimates that if everyone had pure water and satisfactory sanitation, 200 million fewer episodes of diarrheal illness would occur each year
14 billion pounds of garbage are dumped into the ocean annually
Over 1 million seabirds and 100,000 sea mammals are killed by pollution annually
46% of US lakes are too polluted for human activity or aquatic life
