Methods of Monitoring Pollution

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Methods of Monitoring Pollution
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Direct

• Performed by monitoring the level of the
  pollutant itself
• Nitrates in a lake
• Temperature in a stream

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Direct measurements

• Measuring temperature in several locations along
  the length of a river or at different times of
  the year
• Take a baseline measurement and then monitor
  systematically to determine changes
• Measuring nitrate levels/ammonia levels/ chloride
  levels as an indication of nutrient overload
• Measuring TSS or TDS as an indication of material
  entering the lake or stream

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Indirect

• Monitor the effects of the pollutants on other
  factors
• Dissolved oxygen
• BOD
• Presence or absence of indicator species

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BOD

• 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.
• The greater the organic matter (sewage,
  agricultural run-off, fertilizer, etc.) the
  higher the BOD

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More BOD

• If DO equals or exceeds the BOD, the system is
  considered healthy
• If DO level is less than BOD, it is possible that
  there is not enough oxygen to sustain larger
  organisms like fish.
• The process of accumulating large amount of
  organic matter is called eutrophication

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Measuring BOD

• Measure DO on day 1
• again on Day 5
• samples should be kept at 20oC in the dark during
  that time

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Factors Controlling BOD and DO

• A major source of DO comes from the atmosphere
• Moving water is able to dissolve more oxygen
• Temperature is a major factor
• BOD is affected by respiration or lack there of
  by microorganisms and by increase in organic
  matter, waste and sewage

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Biotic index

• Indirect measurement involves monitoring and
  measurement of organisms in the ecosystem
• Indicator or index species
• Species by their abundance or absence indicate
  the level of pollution in an ecosystem
• The diversity of species can indicate the quality
  and overall health of the system

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Important indicators

• Fish
• Bottom fauna
• Algae
• Bacteria
• Comparing the relative abundance of stoneflies,
  mayflies, and caddisflies to midge and
  sludgeworms
• Comparison of diatoms to blue-green algae
• Measuring coliform levels can indicate the
  presence of sewage dumping in the ecosystem
• Overall diversity of the system is the best
  indicator - presence is better than absence