Water Quality and Pollution

Primary Concerns: Water Quality

Runoff (sewage, pesticides, etc.): Biological pathogens/parasites

Secondary concerns: Water Quality

Visible issues, nutrients, odor, oil, pH, organic matter, heat (industry).

How to asses health of waterways

• Physical-chemical indicators

• Turbidity

• Microbiological Indicators

What makes a good microbiological indicator?

High number in feces and low number in unpolluted samples

• Dies off in environment slower than pathogens

• Easy and inexpensive

• Safe

• Stable, high ratio of of indicators/pathogens

Eutrophication

• Nutrients (nitrates, phosphates from human sources)

  • sources: fertilizer, sewage

• Excessive photosynthetic growth

• Decomposition of algal cells depletes dissolved oxygen

Biochemical Oxygen Demand

Amount of DO required by microbes to oxidize the organic matter in a sample.

BOD Test

• Aerate sample (plenty of DO)

• Place in special BOD bottle

• Seed with microbes (if needed)

• Measure initial DO

• Seal bottle

• Incubate for 5 days at 20 degrees celsius

• Measure DO remaining

• Calculate mg of DO used up per Liter of sample

1972 Clean Water Act

• Total maximum daily loads (max amount of pollutant allowed in waterbody to maintain water quality standards

• Discharge permits