The effect of substances on dissolved oxygen level

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The effect of substances on dissolved oxygen level

  1. 1. Anna Ko Annie Au Tim Kind Jade Chen
  2. 2. <ul><li>What is the effect of different substances </li></ul><ul><li> ( elodea, yogurt, dead grass, bar soap, fertilizer ) </li></ul><ul><li>on the dissolved oxygen level ( ±0.1 mg/L ) </li></ul><ul><li>of river water? </li></ul>
  3. 3. <ul><li>DO levels <5.0 mg/L or >110%  stressed aquatic life </li></ul><ul><li>Waste product of photosynthesis  oxygen </li></ul><ul><li>Decay = consumes oxygen </li></ul><ul><li>Temperature may affect DO levels </li></ul>
  4. 4. <ul><li>We predict that the elodea would be the only </li></ul><ul><li>factor to increase the dissolved oxygen level in </li></ul><ul><li>water whereas the rest of the variables would </li></ul><ul><li>decrease the level of dissolved oxygen. </li></ul>
  5. 5. <ul><li>Independent variable: </li></ul><ul><ul><li>substance used </li></ul></ul><ul><li>Dependent variable: </li></ul><ul><ul><li>percent change in dissolved oxygen level </li></ul></ul><ul><li>Control variables </li></ul>
  6. 10. Dissolved Oxygen Levels (±0.1 mg/L) Average Change (±0.6% mg/L) Calibrated Change (±0.6% mg/L) Initial Final Trial 1 Trial 2 Trial 3 Trial 1 Trial 2 Trial 3 Control 4.0 3.8 -5.0 0.0 Elodea 4.3 4.4 4.1 4.0 3.5 3.0 -18.0 -13.0 Yogurt 4.3 4.2 4.3 3.5 2.7 3.0 -22.7 -17.7 Dead grass 4.2 4.1 4.2 3.5 3.0 3.4 -20.8 -15.8 Bar soap 4.1 4.3 4.0 3.3 2.8 3.0 -26.6 -21.6 Fertilizer 4.3 4.2 4.0 3.7 4.3 3.8 -5.6 -0.6
  7. 11. Control Average Percent Change in DO Levels 0.0 -13.0 -17.7 -15.8 -21.6 -0.6 Elodea Dead grass Bar Soap
  8. 12. <ul><li>Hypothesis – wrong </li></ul><ul><ul><li>Assumed that elodea will live in river water </li></ul></ul><ul><li>All substances decreased DO level </li></ul><ul><li>Smallest effect: Fertilizer </li></ul><ul><li>Biggest effect: Bar Soap </li></ul>
  9. 13. <ul><li>DO sensor malfunction  inaccuracies </li></ul><ul><li>Temperature changes (window) </li></ul><ul><li>Holes  diffusion of gases/evaporation </li></ul><ul><li>The effect of river water on elodea </li></ul><ul><li>Time = too long </li></ul>
  10. 14. <ul><li>Control temperature </li></ul><ul><li>Test other living plants </li></ul><ul><li>Control diffusion/evaporation rate </li></ul><ul><li>Increase frequency of DO-measurement </li></ul>
  11. 15. <ul><li>Effect on aquatic life </li></ul><ul><li>Raise awareness of substances that affect DO levels in water </li></ul>
  12. 16. <ul><li>http://www.state.ky.us/nrepc/water/wcpdo.htm </li></ul><ul><li>http://www.fivecreeks.org/monitor/do.html </li></ul>

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