1. YO SYSTEMS STUDENTS!
QUIZ (FRIDAY MAY 23rd) – HYDROSPHERE Syllabus Details A-J

2. Monitoring Water Pollution
Topic 8
A.S: G – J

3. Review of Pollution Monitoring
What does monitoring pollution mean?
Can be:
direct measuring = TESTING FOR POLLUTANT LEVEL
Ex: Testing for nitrates and phosphates, amount of organic matter or bacteria, and heavy metal concentrations (ie: mercury or lead)
or indirect measuring = testing other aspects that can give you an indication of water quality
Abioitic ex: dissolved oxygen (ie Biochemical Oxygen Demand)
Biotic ex: presence or absence of an indicator species =
Why should we measure aquatic pollution in a polluted and unpolluted area (like upstream and downstream)?

4. Why should we measure aquatic pollution in a polluted and unpolluted area (like upstream and downstream)?

5. Dissolved Oxygen
Dissolved oxygen (DO) analysis measures the amount of gaseous oxygen (O2) dissolved in a body of water.
What factors would effect the amount of DO in a body of water?
Light, plant life, any life….like bacteria
Moving water, amount of submerged aquatic vegetation (SAV), temperature, amount of light getting through the water to the SAV.

6. Biochemical Oxygen Demand
Biochemical Oxygen Demand or Biological Oxygen Demand (BOD) is a how fast bacteria use up oxygen in a body of water
Measures the amount of dissolved oxygen needed by aerobic decomposers to break down the organic materials in a given volume of water
What pollutants would cause BOD to go up?
So is a high BOD good or bad for an aquatic ecosystem?
Why?

7. BOD Test
BOD measures mass (in milligrams) of dissolved oxygen consumed per liter of water.
Sample bottle is filled completely submerged underwater.
Why?
DO is tested.
Sample is incubated at a temperature of 20°C for five days in the dark.
Why in the dark?
DO is tested again…how do you then calculate BOD?

8. BOD Values? Most pristine rivers will have a 5-day BOD below 5 mg/L
Moderately polluted rivers may have a BOD value in the range of 5 to 10 mg/L
Municipal sewage that is efficiently treated would have a value of about mg/L.
Untreated sewage varies, but averages around 350 mg/L
Cattle slurry is around 10,000 mg/L
Paper pulp mill is around 25,000 mg/L

9. Indirect Method using Biotic Index
A biotic index is a scale (1-10) that gives a measure of the quality of an ecosystem by the presence and abundance of certain species living in it.
Indicator species = plants or animals that show something about the environment by their presence, absence, abundance or scarcity.
They are early warning signs because they are the most sensitive to change or they are very tolerant of chemicals or low levels of oxygen.
Why are these indirect methods?

10. Using the method
How could you use this method to determine if an area of a river is polluted?
Kick nets for Biotic Index
Water Sample for BOD
BOD and Biotic Indices are usually used together:
What does the Biotic Index show that BOD and direct pollution monitoring does not?

11. Collecting Organisms

12. Turbidity
Turbidity is the cloudiness or haziness of a fluid caused by individual particles, that are generally invisible to the naked eye
The measurement of turbidity is a key test of water quality
How can Turbidity affect the health of an aquatic ecosystem?

13. For use in shallow or moving water
Monitoring Turbidity
Turbidity Tube
Turbidity Tube
For use in shallow or moving water
Using a Secchi Disk to measure the depth of water where photosynthesis can still occur
Turbidity Columns
1 is the control with distilled water and the other has the sample water

14. Flow Velocity The speed of water movement
Normally studied in streams or rivers
Time how long it takes for objects to pass between two poles 5 meters apart at different depths and take an average.
How might flow velocity affect the health of an aquatic ecosystem?