1. 5.2 Detection and Monitoring of Pollution

2. Direct measurement is performed by monitoring the level of the pollutant itself, e.g. nitrates in a lake or temperature levels in a lake or stream.
Indirect method would monitor the effects of the pollutants on other factors, e.g. dissolved oxygen, B.O.D.5,
Indicator Species presence or absence of indicator species

3. Direct Measurement Some direct measurements might include:
1.Measuring temperature in several locations along the length of a river, or at different times during the year with thermometers as an indication of thermal pollution. 2.Take baseline measurements and then 3.Monitor in a systematic manner to determine changes.
measuring nitrate levels/ammonia levels/chloride levels as an indication of nutrient overload. Use the same process as above
measuring TSS (Total Suspended Solids) or TDS (Total Dissolved Solids) as an indication of material entering the lake or stream. (see next slide)

4. Indirect Measurement
BOD is the measure of the amount of dissolved oxygen that is used by aerobic bacteria to break down the organic matter in a specific volume of water.
Therefore the greater the amount of organic matter/nutrient (sewage, agricultural run-off, fertilizer etc.) in the body of water, the higher the BOD will be. The less organic matter, the lower the BOD.
It is not uncommon for the BOD of incoming water to a sewage treatment plant to be around 120.

6. This is done by measuring the DO (dissolved oxygen) on day
Keep samples at 20 degrees Celsius for 5 days in the dark during that time.
Measure the DO again on the 5th day.
This measures the respiration going on and not photosynthesis.

7. Natural factors that influence dissolved oxygen:
Aquatic life-animals:
Stonefly living in water use up dissolved oxygen. Bacteria take up oxygen as they decompose materials.
Elevation:
the amount of oxygen in the atmosphere decreases as elevation increases. Since streams get much of their oxygen from the atmosphere streams at higher elevations will generally have less oxygen.
Salinity:
Salty water holds less oxygen than fresh water.
Temperature:
Cold water holds more dissolved oxygen than warmer water.
Turbulence:
More turbulence creates more opportunities for oxygen to enter streams.
Vegetation:
riparian vegetation directly affects dissolved oxygen by releasing oxygen into the water during photosynthesis. It indirectly affects dissolved oxygen concentrations because vegetation shading a stream may decrease water temperatures.

8. Human factors that influence dissolved oxygen:
Factories and powerplants
Factors and powerplants will emit hot water from effluent ponds. These emissions will impact the DO of the body of water as they enter.
Clearing land
(e.g., construction, logging)-may send excess organic matter into streams. Organic matter is decomposed by microorganisms, which use up oxygen in this process. Therefore, if there is a lot of organic waste in the stream the microorganisms use more oxygen than can be replaced in the stream.
Destruction of riparian areas
(e.g., development or overgrazing) decreases the amount of shade and increases the water temperature. Warmer water holds less DO than colder water.

9. BOD5 Level BOD Level (in ppm) Water Quality 1 - 2
Very Good There will not be much organic waste present in the water supply.
3 - 5
Fair: Moderately Clean
6 - 9
Poor: Somewhat Polluted Usually indicates organic matter is present and bacteria are decomposing this waste.
100 or greater
Very Poor: Very Polluted Contains organic waste.

10. Indirect measurement
Indirect measurement involves the monitoring and measurement of organisms in the ecosystem and more specifically indicator species or index species. These are species that by virtue of their abundance or absence will indicate the level of pollution in that ecosystem.

11. Macroinvertebrate indicator species
Easy to see and identify e.g. mayflies, caddisflies, true flies, snails (see keys)
Have a life cycle of at least a year
Relatively sedentary, confined to the area being sampled
They have a range of responses to different pressures.
Individual species have specific tolerance ranges and habitat requirements

12. Aquatic Invertebrate Data Recording Sheet

13. Using the biotic index
These scores are then combined to produce a single value which can be used to interpret the current state of the environment.
Examples of biotic indices
Trent Biotic Index, the Chandler Score and the Biological Monitoring Working Party (BMWP) score

14. The damselfly larva Calopteryx splendens

15. The damselfly larva Calopteryx splendens
The presence of this larva indicates clean water
Slow flowing water and a silted river bed.
It is also intolerant of acidification and increased salinity
Species like C. Splendens are used to formulate biotic indices based on acidification, flow velocity and siltation

16. Pollution Tolerant Species:
Presence of these species indicate water of low quality, however they may be present in all types of water.
blackfly larvae
Flatworms
Leeches
Roundworms
Blood worms/midge larvae

17. Moderately Tolerant Species:
Presence of these species in great numbers may be a
sign of fair water quality.
caddisfly larvae
dragonfly nymphs
damselfly nymphs

18. Pollution Intolerant species
Presence of these species in great numbers may indicate good water quality.
mayfly nymphs
stonefly nymphs

19. Comparison of diatoms to blue-green algae provides similar information
Measuring the coliform levels can also indicate the presence of sewage dumping in the ecosystem.

20. The Macroinvertebrate biotic index
To arrive at an indication of your sites biotic index level, multiply the number of organisms collected by the tolerance rating.
Add all the numbers in the organism column and all the numbers in the tolerance value column.
Divide the tolerance value with the organisms total. This results the biotic index based on the biological specimens collected.

21. Example of Biotic Index Calculation Using Macroinvertebrate Information
You may find in an aquatic ecosystem:
25 Mayfly larvae
15 Caddisfly larvae
20 Stonefly larvae
20 leeches
20 Midge larvae

22. Multiply each by the Biotic Value:
No of organisms X biotic value
Biotic value
25 Mayflies
5.5
15 Caddisflies
20 Stoneflies
1.5
20 leeches
8.0
20 Midge larva
4.0
Total number of organisms =
TOTAL biotic value =

23. Very poor > 9.0 poor 7.6-8.9 Fair 6.1-7.5 good < 6.0
Divide total biotic value by the total number of organisms to get the biotic index value
Water Quality Biotic Index
The biotic index value is …………….
Use chart to determine water quality based on Biotic Index Value
Based on the Biotic Index Value, the water quality is ………………………
Very poor
> 9.0
poor
Fair
good
< 6.0

24. Worked example: BIOTIC VALUE 25 Mayflies 5.5 25 x 5.5 137.5
15 Caddisflies
15 x 5.5
82.5
20 Stoneflies
1.5
20 x 1.5 30
20 leeches
8.0
20 x 8
160
20 Midge larva
4.0
20 x 4 80
Total number of organisms = 100
TOTAL biotic value = 490

25. Very poor > 9.0 poor 7.6-8.9 Fair 6.1-7.5 good < 6.0
Divide total biotic value by the total number of organisms to get the biotic index value
Water Quality Biotic Index
490/100 = 4.9
Use chart to determine water quality based on Biotic Index Value
Based on the Biotic Index Value, the water quality is good.
Very poor
> 9.0
poor
Fair
good
< 6.0

26. Diatoms

27. Fecal Coliform

28. Blue-green algae

29. Overall the diversity of the whole system is often the best indicator while a general rule to follow is that presence is better evidence than absence.