1. Chapter 22 Water Pollution

2. Types of Water Pollution
Any physical or chemical change in water that adversely affects the health of humans and other organisms
Varies in magnitude and type of pollutant by location
Major water pollution issue globally
Lack of disease-free water

3. Types of Water Pollution
Eight categories
Sewage
Disease-causing agents
Sediment pollution
Inorganic plant and algal nutrients
Organic compounds
Inorganic chemicals
Radioactive substances
Thermal pollution
Some categories are interrelated

4. Sewage The release of wastewater from drains or sewers
Includes human wastes, soaps, and detergents
Causes 2 serious environmental problems:
Enrichment
Increase in Biological Oxygen Demand (BOD)

5. Enrichment
Fertilization of a body of water by high levels of plant and algal nutrients (nitrogen and phosphorus)
Microorganisms decompose materials into CO2, water, other inoffensive materials
Cellular respiration – requires oxygen

6. Biological Oxygen Demand
Amount of oxygen needed by microorganisms to decompose biological wastes
Expressed as mg of DO/L for a specific number of days at a given temperature
As BOD increases Dissolved Oxygen (DO) decreases

7. Dissolved Oxygen Oxygen has a limited ability to dissolve in water
When aquatic ecosystem contains a large amount of sewage, decomposing organisms use up most of DO
Little left for fishes and other aquatic animals
Extremely low DO, anaerobic microorganisms produce compounds with unpleasant odors
Further deteriorates water quality

8. Dissolved Oxygen

9. Oligotrophic Lake
Unenriched, clear water that supports small populations of aquatic organisms

10. Eutrophic Lake
Slow-flowing stream, lake or estuary enriched by inorganic plant and algal nutrients such as phosphorus
Often due to fertilizer or sewage runoff

11. Eutrophication
Enrichment of lake, estuary, or slow-flowing stream by inorganic plant and algal nutrients
Increased photosynthetic productivity
Water becomes cloudy (pea soup-like) because of presence of algae and cyanobacteria

12. Eutrophication Over time, bodies of water become eutrophic naturally
Slowly grow enriched, shallower
Plants start to take root
Becomes a marsh
Artificial eutrophication – human-induced process
Fertilizer runoff and sewage

13. Disease-causing Agents
Infectious organisms that cause diseases
Originate in the wastes of infected individuals
Common bacterial or viral diseases:
Typhoid, cholera, bacterial dysentery, polio, and infectious hepatitis

14. Disease-causing Agents
Monitored by testing for presence of E. coli in the water via a fecal coliform test
Indicates the presence of pathogenic organisms

15. E. Coli Safe drinking water – no more than 1 bacterium/100 mL
Safe swimming water – no more than 200/100 mL
Safe general recreation water (boating) – no more than 2000/100 mL
Raw sewage – several million/100 mL

16. Sediment Pollution Excessive amounts of suspended soil particles
Originates from erosion of agricultural lands, forest soils exposed by logging, degraded stream banks, overgrazed rangelands, strip mines, and construction
Problems
Limits light penetration
Covers aquatic animals and plants
Brings insoluble toxins into waterways

17. Sediment Pollution Makes water turbid (cloudy) Extreme turbidity
Reduces number of photosynthetic algae and plants that require light for photosynthesis
Decreases number of aquatic organisms that feed on producers
Sediments can form layer over coral reefs or shellfish beds that can clog gills and feeding structures of aquatic animals

18. Sediment Pollution
Particles can also carry toxic chemicals (inorganic and organic) into water
Can also transport disease-causing agents

19. Sediment Pollution
1998 EPA study – sediments in 7% of watersheds are so seriously contaminated with toxic pollutants that eating fishes from those waterways would threaten human health
Sediments can fill in waterways – problem in lakes and channels through which ships have to pass

21. Inorganic Plant and Algal Nutrients
Chemicals such as nitrogen and phosphorus that stimulate the growth of plants and algae
Essential for normal functioning of healthy ecosystem
Harmful in large concentrations
Sources:
Human and animal wastes, plant residues, atmospheric deposition, and fertilizer runoff
Causes:
Enrichment, bad odors, and a high BOD

22. Mississippi Dead Zone

23. Mississippi Dead Zone
Fertilizer runoff from midwestern fields, manure runoff from livestock operations
1998 Senate Agriculture Hearings -- US livestock produce 20 times the feces and urine that humans do
Not covered by water quality laws
Do not go to wastewater treatment plants

24. Mississippi Dead Zone
Dead zone extends from sea floor up into water column to within several meters from surface
Floods and droughts change its size
Persists from March/April to September
Most severe in June, July, August
2002 – more than 22,000 km2 – size of Massachusetts

25. Mississippi Dead Zone No life other than anaerobic bacteria
Active swimmers avoid area
Bottom dwellers suffocate
Hypoxia affects more than 146 coastal areas in world

26. Organic Compounds Chemicals that contain carbon atoms
Natural examples: sugars, amino acids, and oils
Human-made examples: pesticides, solvents, industrial chemicals, and plastics

27. Organic Compounds 2002 USGS Study of 139 streams in 30 states:
Tested for 95 organic compounds
Found low concentrations of 82 compounds
One found in 80% of streams
More than 1/3 contained traces of 10 or more
Effects on human health largely unknown

28. Inorganic Chemicals
Contaminants that contain elements other than carbon
Examples: acids, salts, and heavy metals
Do not degrade easily

29. Lead Found in old paint, industrial pollutants, leaded gasoline
1978 – lead paint banned
1986 – leaded gasoline outlawed
Dust released into atmosphere, contaminates soil, especially inner cities near highways
Contaminates soil, surface water, and groundwater when incinerator ash dumped in landfills
Pesticides, fertilizers
Food cans and certain types of dinnerware

30. Mercury Vaporizes at room temperature
Coal-fired power plants release 40% of mercury in environment
Fluorescent lights and thermostats
Also released during metal smelting
Mercury bioaccumulates in the muscles of top predators of the open ocean
Human exposure primarily due to eating fishes and marine mammals

31. Radioactive Substances
Contain atoms of unstable isotopes that spontaneously emit radiation
Sources
Mining
Processing radioactive materials
Nuclear power plants
Natural sources

32. Thermal Pollution
Occurs when heated water produced during industrial processes is released into waterways
Organisms affected
Temperature affects reproductive cycles, digestion rates, and respiration rates
Warm water holds less DO than cold water