BIOL354 Lecture Notes - Lecture 6: Chemical Oxygen Demand, Biochemical Oxygen Demand, Sewage Sludge
25 Dec 2012
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Document Summary
Review: gamma rays (3-10 mega electron volts); 3 stages of dose dependent radiation outcome: Haematopoietic effects; gastrointestinal effects; central nervous system effects. Few # of people died due to drinking e. coli contaminated well water. Chlorine was not added and many residents developed gi diseases. Currently, walkerton has the best water treatment plan in canada. Pollutant sources (2: accidental release (can"t be eliminated, maybe minimized) Nuclear accidents (chernobyl & fukushima daiichi), oil spills (exxon valdez & deepwater horizon: international release (acknowledged as undesirable, no other methods, full extent of toxicity unknown) Intentionally applied pollutants (pesticides, fertilizers, manure e. coli, sewage sludge applied above surface) Storage (septic) tanks needed to be cleaned out seasonally (leak into lands) Indirect (highly dynamic): automobile, exhaust, mines, landfill leachates, etc. Road salt, fertilizers, pesticides can leach into the soil -> can contaminate groundwater. May not be able to replace as of now, but should be applied wisely.
