Point and non-point Sources

A point source is pollution that is coming from a distinct "point" such as a sewer outfall. They are

often regulated.

Non-point sources cannot be easily traced back to a particular location. This type of water pollution

much harder to control, since it comes from many diverse things.

The way non-point pollution reaches our water sources is through runoff and infiltration.

Factors Affecting DO

velocityIn fast-moving streams, rushing water is aerated by bubbles as it churns over rocks and falls down waterfalls. In slow, stagnant waters, oxygen only enters the top layer of water.

Depthdeeper water is often low in DO concentration due to decomposition of organic matter by bacteria that live at the bottom.

Also, less light means less photosynthesis.

Factors Affecting DO

TemperatureThe colder any liquid is, the more gas will stay dissolved in it.

(Pond turnovers)

The type and number of organisms in the water bodyBacteria and fungi use oxygen as they decompose dead organic matter in the stream.

Amount of nutrients in the waterPotentially leading to eutrophication and hypoxia

Waterborne Diseases

Waterborne diseases - Bacteria

• Name: Botulism• Caused by: bacteria Clostridium botulinum• Notes: can grow in canned food processed

with unsanitary water; also used in Botox

Waterborne disease - Bacteria

• Name: Cholera• Caused by: Vibrio cholerae• Notes: can kill a person in a matter of hours.

Symptoms, including severe watery diarrhea, cause extreme dehydration and kidney failure.

• John Snow in England

Waterborne disease - parasite

• Name: Schistosomiasis• Caused by: parasitic flatworm of genus

Schistosoma• Notes: very common, yet very easily treatable,

in 3rd world countries with poor sanitation

Organisms and oxygen

• Aerobes – need oxygen; use cellular respiration

• Anaerobes – do not need oxygen (in fact, oxygen will kill them); use fermentation.

• Facultative anaerobes – can do either one; they switch to fermentation when there’s no oxygen.

Biochemical Oxygen Demand

• The amount of oxygen required by aerobic microorganisms to decompose organic matter in water.

• It is used as a measure of water pollution.

Turbidity• Turbidity is the cloudiness or haziness of a fluid

caused by solid particles suspended in a liquid.

Turbidity

• Causes: – Sediment (erosion, human activities)– Phytoplankton– Polluting chemicals

Secchi Disk

Wastewater Treatment

Primary Treatment

• What does it do?• Removes large waste objects, solids, and

grease

• How does it do this?– Bar screen– Grit chamber– Primary Clarifier

Secondary Treatment

• What does it do?• Further breaks down smaller impurities, using

bacteria.

• How does it do this?– Aerator (bacteria)– Secondary Clarifier

Tertiary Treatment

• What does it do?• Final preparation before water leaves: killing

off germs, removing chemicals.

• How does it do this?– Chlorine or UV rays– Reverse osmosis, et al.

Water Regulation

Clean water act 1972

• Reaction to US waters becoming very polluted• Regulated discharge of pollutants into

“navigable waters”• Set standards and provided enforcement

Safe Drinking Water Act 1974

• Higher standards for water for human consumption

• Lead-free plumbing

Indicator Species

• What is it?– An indicator species is an organism whose

presence, absence or abundance reflects a specific environmental condition.

• Amphibians make good indicator species, due to their sensative, moist skin and “two lives”