1. Section #3: Water Pollution

2. Water Pollution
the introduction of chemical, physical, or biological agents into water that degrade water quality and adversely affect the organisms that depend on the water
can’t always tell if a body of water is polluted by the look or smell

3. Water Pollution
developed countries have cleaned up their act in the past 30 years, but some waters are still at dangerous levels
developing countries have a much bigger problem, mostly from sewage & agricultural runoff

4. Point-Source Pollution
pollution that is discharged from a single source
usually can be identified & traced
but even when the source of the pollution is located, enforcing clean-up can be difficult

5. Point-Source Pollution

6. Nonpoint-Source Pollution
pollution is coming from multiple different sources that are difficult to identify
any pollution to the land in a watershed area can be carried to a river or stream from rain runoff
extremely difficult to regulate or control

7. Nonpoint-Source Pollution

8. Controlling a Major Problem
96% of polluted bodies of water in the U.S. were contaminated by nonpoint sources
control depends on public awareness of the effects of activities such as spraying lawn chemicals & disposing of motor oil in storm drains

9. Types of Pollutants
pathogens – nonpoint sources (sewage, animal feces, poultry farms, wastewater treatment plants)
organic matter – nonpoint sources (food waste, debris, feces, remains of dead organism)
organic chemicals – nonpoint sources (pesticides, fertilizers, plastics, detergents, petroleum products, gasoline, oil)
inorganic chemicals – point & nonpoint sources (acids, bases, salts, industrial chemicals)
heavy metals – point & nonpoint sources (Pb, Hg, Cd, As from industrial discharge, unlined landfills, mining processes)
physical agents – point & nonpoint sources (heat from industrial processes)

10. Wastewater water that contains waste from homes or industry
carried to a wastewater treatment plant where it is filtered & treated to make the water clean enough to return to a river or lake

11. Treating Wastewater
most of the wastewater from homes contains biodegradable material (animal & plant waste, paper, soap) that can be broken down by living organisms (like bacteria)

12. Wastewater Treatment Process

13. Sewage Sludge a product of wastewater treatment
the solid material that remains after the water is treated
sometimes contains dangerous levels of toxic chemicals & must be treated as hazardous waste
usually burned & ash is buried in a landfill

14. Disposal of Sewage Sludge
becoming a huge problem because the volume of sludge is enormous
sludge that is not toxic can be used as fertilizer, can be combined with clay to make bricks for building, can also be used to make creative sculptures

15. Eutrophic Bodies of Water
a build up of nutrients in a body of water (like a lake)
most nutrients that enter water come from organic matter & play a key role in the aquatic ecosystem
decomposition of this organic matter uses up O2 that sets up a chain reaction of events that can dramatically change the body of water

16. Artificial Eutrophication
when human actions accelerate the natural process of eutrophication
phosphorous, nitrogen, and other inorganic plant nutrients enter the water from sewage & fertilizer runoff

17. Algal Blooms

18. Thermal Pollution when the temperature of a body of water increases
occurs when power plants & other industries use water in their cooling systems & then discharge the warm water back into a lake or stream
warm water does not hold as much O2 as cold water does leading to suffocation & death

19. Thermal Pollution

20. Groundwater Pollution
pesticides, herbicides, chemical fertilizers, & petroleum products on the land surface or in bodies of water can percolate down into the Earth & become part of the groundwater system
leaking from underground storage tanks (most hold petroleum products) is another major source

21. Underground Storage Tanks
as the tanks age, they begin to leak
the location of most tanks is unknown so tanks cannot be repaired or replaced
once they are located, it is often too late and the leak has spread
modern tanks are contained in layers of concrete to help contain leaks

22. Contamination of Groundwater by Leaking Underground Storage Tanks
UST
Water Table
Contaminating the water table

23. Other Sources septic tanks that leak or overflow
unlined landfills that allows precipitation to seep through, carrying pollutants with it into the ground
industrial wastewater lagoons that are not maintained or lined

24. Major Sources of Groundwater Pollution

25. Cleaning Up Groundwater Pollution
one of the world’s most challenging problems
even if we could stop all groundwater pollution this minute, the groundwater would remain polluted for 100s or 1000s of years
the area is too large to completely clean
pollution can cling to the rock material

26. Ocean Pollution
too often, pollutants are dumped directly into the ocean – sometimes legally!
ships are allowed to dump wastewater & garbage overboard in some parts of the ocean
most of the pollution entering the ocean (oil, toxic waste, medical waste) comes from activities on land
most affected areas include coral reefs, estuaries, & coastal marshes

27. Oil Spills
oil spills make big news (think Exxon Valdez) & approximately 37 million gallons of oil from tanker accidents spills into the ocean
tanker oil spills accounts for on 5% of oil in the ocean, most oil pollution comes from cities & towns & other nonpoint sources on land

28. Major N. Am. Oil Spills

29. Impact on Ecosystems
some pollution can kill all living organisms for miles downstream
but most pollutants do their damage after they accumulate (due to slow decomposition)
biomagnification occurs & has the biggest impact on organisms at the top of the food chain

30. What is Biomagnification?
an accumulation of pollutants (such as pesticides) at successive levels of the food chain
zooplankton – small fish – medium fish – large fish – bird (or human)
each organism stores the pesticide in its tissues, so at each step along the food chain, the amount of the pesticide passed on to the next organism increases

31. Biomagnification

32. Federal Laws for Improving Water Quality
Clean Water Act (1972)
Marine Protection, Research, & Sanctuaries Act (1972)
Safe Drinking Water Act (1975)
Comprehensive Environmental Response Compensation & Liability Act (1980)
Water Quality Act( 1987)
Oil Pollution Act (1990)

33. Cleaning Up Water Pollution

34. Cleaning Up Water Pollution