1. Water Pollutants
Biological
Physical
Chemical

2. Biological Pollutants
Consists of pathogens (disease-causing agents)
Come from sewage
Diseases include;
Typhoid, cholera, dysentery, polio, infectious hepatitis, salmonella, E-Coli bacteria

3. Temperature Referred to as Thermal Pollution
Gases do not readily dissolve in liquids with high temperatures.
↑T → ↓ DO
Power plants sometimes use waterways to cool their equipment. Replaced waters are warmer than they were before causing DO ↓
Cooling towers can be built to cool the water before they are discharged back into the water body.

4. Dissolved Oxygen (DO) DO gets into the water by:
1) moving water (riffles, rapids, water falls, etc.)
2) photosynthesis of aquatic plants
Gases do not readily dissolve in liquids with high temperatures.
↑T → ↓ DO

5. BOD (Biological Oxygen Demand)
Can be used as a gauge of the effectiveness of wastewater treatment plants
The amount of oxygen needed for microorganisms to break down organic waste material
High BOD indicates high levels of organic contaminants in the water
Sewage = organic wastes; decomposers work to break down the waste – which takes oxygen;
↑ BOD → ↓ DO

6. Dilution and decay of degradable, oxygen-demanding wastes and heat in a stream.
Figure 21-4

7. Sedimentation Excessive amounts of suspended solids in water.
Come from soil erosion
Increases turbidity (the cloudiness or haziness of a fluid caused by suspended solids) which reduces the amount of sunlight that penetrates the water
↓ photosynthesis → ↓ DO
Slows water flow → ↓DO

8. Chemical Pollutants pH plant nutrients heavy metals
radioactive substances

9. pH
3.0 – 3.5 = toxic to most life
3.5 – 4.0 = lethal to trout and other fish
4.0 – 4.5 = fish eggs; dead lake
5.0 – 6.0 = changes ecology (biodiversity, #, decline is fish species, slow decomposition, nutrients trapped at bottom, algae disappears)
6.5 – 9.0 mostly harmless
9.0+ harmful to lethal as pH goes up to 11.5

10. Plant Nutrients Nitrites/nitrates; phosphorous increases plant growth;
sources: fertilizers, sewage
causes algal bloom; eutrophication
↑ plant life → blocks sunlight → ↓ photosynthesis → plants die → ↑BOD → ↓DO → fish kill

11. Heavy Metals – Mercury (Hg)
Sources
leaching of soil due to acid rain, burning coal, industrial, household and mining wastes.
Health Concerns
damages nervous system, kidneys, vision, Minimata
1932 – 1968 – Co dumped 27 tons mercury compounds into Minimata Bay – Hg converted to methyl mercury – ingested by eating fish – 43 people died

12. Heavy Metals – Lead (Pb)
Sources:
paint, mining, incinerator ash, lead pipes and solder (contaminate water), auto exhaust
Health Concerns
damage to kidneys, nervous system (brain), ability to learn, depressed biosynthesis of proteins, nerves, red blood cells; anemia, irritability

13. Heavy Metals – Cadmium (Cd)
Sources:
electroplating, mining, plastic industries, sewage
Health Concerns
kidney disease

14. Heavy Metals – Arsenic (As)
Sources:
herbicides, wood preservatives, mining industry
Health Concerns
Damage to eyes, skin, GI tract, liver; cancer

15. Heavy Metals – Aluminum (Al)
Sources:
leaching due to acid rain
Health Concerns
anemia, loss of bone strength; possible role in dementia, and Alzheimer’s

16. Radioactive Substances
oceans become contaminated by nuclear waste from illegal dumping, bomb tests, and nuclear accidents

17. Monitoring Water Pollution
Nitrate and Phosphate tests
Fecal Coliform Test
Heavy Metal Tests
BOD
Changes in biodiversity of ecosystems
Mortality of indicator species
DIRECT
TESTS
INDIRECT
TESTS

18. Point Source Pollution
a single identifiable localized source of pollution
easier to control emission, attribute responsibility and take legal action
Ex) Water pollution from an
oil refinery wastewater
discharge outlet

19. Non-Point Source Pollution
Derived from many different sources often in the form of runoff
It is difficult to regulate.

20. Reducing Water Pollution through Sewage Treatment
Primary and Secondary sewage treatment.
Figure 21-16

21. Waste Water Treatment Removes the following:
Silt
Phosphorus
Dissolved organic wastes
Sludge
Sewage adds nitrogen and phosphorus to the water which can lead to eutrophication in bodies of water
Fecal coliform test is used to detect sewage in contaminated water

22. Sewage Treatment
Natural and artificial wetlands and other ecological systems can be used to treat sewage.( Bioremediation)

23. Bioremediation
the use of microorganismal metabolism to remove pollutants.
Composting can be classified as bioremediation
Heavy metals are not easily treated by bioremediation

24. Bioremediation

25. Phytoremediation
consists in mitigating pollutant concentrations with plants able to contain, degrade, or eliminate pollutants from water, soil, or air
Pollutants include: metals, pesticides, solvents, explosives, crude oil and its derivatives, and other contaminants

26. How do plants do what they do?