Water Pollution Continued…. Oil Exxon Valdez 11 million gallon oil spill @ a rate of 20,000 barrels/hr – March 24, 1989 Ran aground on Bligh reef – 40km.

Water Pollution Continued…

OilExxon Valdez 11 million gallon oil spill @ a rate of 20,000 barrels/hr – March 24, 1989

Ran aground on Bligh reef – 40km southe of Valdez - Prince William Sound, AK – end of Aleyeska pipeline

Impact to wildlife – ½ million sea bird deaths, 28% of otters killed, seals, bald eagles, orcas

Toxic Substances

3 categories covered in later chapters in the book:

1. Hazardous chemicals – sythetic organic and inorganic compounds

2. Heavy metals – lead, mercury, zinc and cadmium – deposited on floodplains – incorporated into crops – can cause heavy metal poisoning – peripheral neuropathy

3. Radioactive materials

Sediments and Thermal Pollution

Seemingly innocuous, sediment and heat can pollute certain envts.

Seds – from uncontrolled development can choke fluvial resources and degrade natural systems

Heat – from industrial operations and power plants hot water emmissions – decreases ability to hold oxygen – think Trout streams.

Point source vs. Non-point source

Pt. sources = discrete, confined, easier to identify and control

Non-point source = e.g. polluted runoff – difficult to control because it is coming from “everywhere”

Diffuse and intermittent

Examples: Acid mine drainage, Agricultural run‑off

Acid Mine Drainage

Refers to acidic water draining from mines

Sulfuric Acid - H2SO4 produced by weathering – sulfide mineralization

Occurs when sulfide minerals associated with coal and metal (zinc, lead, copper) mining come into contact w/ oxygen-rich water

Sulfuric acid is extremely toxinc to plants/animals in aquatic ecosystems

Salt Water Intrusion

As discussed in our Long Island, NY example.

GHYBEN-HERZBERG PRINCIPAL - The principal states that where readily permeable aquifers exist in coastal zones, for every foot of water-table height above sea level, the freshwater-saltwater interface will be about 40 feet below sea level. The principle reflects the fact that freshwater is 1/40 less dense than sea water.

Groundwater Dependence/Treatment

Since approx. ½ of the U.S. population depends on groundwater for drinking water, we are highly concerned about the pollution of our aquifers

75% of 175,000 known waste disposal sites are producing contaminant plumes beneath the water table

Steps in treatment

Characterize the geology

• Structures that control the direction and quantity of groundwater flow

Characterize the hydrology

• Depth to water, flow direction and rate, relationship with surface water also may be important

Identify contaminants and transport processes

• Floaters (e.g. Gasoline)

• Sinkers (e.g. TCE = Trichloroethane)

• Dissolved (e.g. components of unleaded gas, MTBE, salts)

Initiate Treatment

Groundwater Pollution Treatment

Wastewater Treatment – Septic tank sewage disposal

Common in rural areas and many fast growing communities with no treatment facilities (about 30% nationally)

25% of all Floridians

On-site disposal

Requires soil testing

Wastewater Treatment Plants(Best for urban areas with poor drainage)

Primary treatment ‑physical removal of solids; removes 30‑40% of pollutants

Secondary treatment ‑follows primary with some chemical treatments; removes 90% of pollutants

Tertiary or advanced treatment Adds treatment to remove N and P and most bacteria Reclaimed water can be used for certain activities such as watering campus, golf courses, industrial use, and agriculture