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Dissolved Oxygen in Water

Dissolved Oxygen in Water. With real-life, horrifying sea creatures on every slide. Dissolved Oxygen. The concentration of oxygen in the water. Known as DO Lowest amount needed for fish is 0.003g/dm 3. Dissolved Oxygen. The highest DO possible is 0.009g/dm 3

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Dissolved Oxygen in Water

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  1. Dissolved Oxygen in Water With real-life, horrifying sea creatures on every slide.

  2. Dissolved Oxygen • The concentration of oxygen in the water. • Known as DO • Lowest amount needed for fish is 0.003g/dm3

  3. Dissolved Oxygen • The highest DO possible is 0.009g/dm3 • Oxygen has low solubility because the diatomic molecule is non-polar. • Rivers have higher DO because of the rushing water, and can replace its DO faster.

  4. BOD (IB Assessment) • Biochemical Oxygen Demand • It’s the amount of oxygen (in ppm) needed by bacteria to decompose organic waste in water at a specified time at a specified temperature (usually 5 days at 20⁰C). • A measure of pollution

  5. BOD (IB Assessment) • The higher the BOD, the more polluted the water is, the more oxygen needed to oxidize the water. • The more oxygen present in the water, the lower the BOD should be. • Fish (and other organisms) cannot survive in an environment where the BOD is greater than the DO.

  6. BOD Table

  7. Winkler Method • Method to figure out the BOD. • The water is saturated to its maximum amount of DO. • Bacteria is left in the water for five days in a temperature of 25⁰C. • The remaining oxygen is measured using titration.

  8. Aerobic vs. Anaerobic (IB Assessment) Aerobic Decomposition Anaerobic Decomposition • Uses oxygen • Oxidizes compounds • Does not use oxygen • Reduces compounds • Creates a bad smell

  9. Decay Products

  10. Eutrophication (IB Assessment) • Addition of nutrients to the point of excess (usually from fertilizers or acid rain). • Overabundance of plants and algae. • Due to overabundance, all the oxygen in the water is used up, and the plants die. • Creates a lot of organic matter to be decomposed, raising the BOD.

  11. Eutrophication (IB Assessment) • Because of the lack of oxygen, anaerobic decomposition takes place, creating bad smelling gases that poison the water. • Area dies completely from the lack of oxygen and poisonous compounds. • Calcium or aluminum ions can be used to remove the phosphates. • Nitrates are much harder to remove, reverse osmosis and ion exchange techniques are needed.

  12. Thermal Pollution (IB Assessment) • Water used for cooling in powerplants are dumped into rivers, causing thermal pollution. • Thermal pollution decreases the concentration of oxygen. • Thermal pollution increases metabolism, increasing the amount of oxygen needed for respiration, and therefore increasing the BOD.

  13. Thermal Pollution (IB Assessment) • With a decrease in oxygen concentration and an increase in the BOD, the environment cannot be supported, and anaerobic respiration takes place. • Sudden increase in temperature can disrupt life cycles such as reproduction, or just kill organisms (increasing the BOD). • Can be solved by trickling water through a porous material while blowing air in the opposite direction

  14. The End

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