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Learn about the devastating impact of the Exxon Valdez oil spill and the toxic substances that pollute our water. Explore the effects on wildlife, sediment and thermal pollution, acid mine drainage, and saltwater intrusion. Discover the importance of groundwater treatment and wastewater treatment plants in combating pollution.
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Oil Exxon 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 • 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 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
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
