water pollution continued…. oil exxon valdez 11 million gallon oil spill @ a rate of 20,000...
TRANSCRIPT
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