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Types of Pollution
Pollution is any substance that has a negative effect on living things. There are several categories of pollution including sediment, toxic chemicals, warm water and organic nutrients.
Sediment Pollution
Toxic Pollution
Thermal Pollution
Organic Nutrient Pollution
Sediment Pollution
Particles that wash into a river may originate from street runoff during storms or during spring snowmelt. Sediment can also originate from construction areas, trampled banks or flood events.
- Measuring the turbidity (clarity) of the water can serve as a test for sediment pollution.
Sediment pollution does damage when suspended particles gradually settle over the river bottom. The effects of sediment pollution can include:
- reduced number of invertebrates and invertebrate types
- smothering and killing fish eggs, algae and invertebrates
- murky water that blocks sunlight for photosynthesis
- rocks and plants covered in silt
Toxic Pollution
Chemicals that are harmful to life can originate from storm sewer outlets, water treatment plants, factories, rail yards, lawns, golf courses and mines. These chemicals can include paint, diesel fuel, chlorine, oil, acid, pesticides, herbicides and heavy metals.
- Analysis of invertebrate data can serve as a measure of toxic pollution. Testing for specific toxins is usually beyond the scope of school and public monitoring programs.
The effects of toxic pollution can include:
- reduction or absence of all types invertebrates
- water appears clear and clean
Thermal Pollution
Human activities can return warm water to a river. Sources of thermal pollution can include power plants, wastewater treatment plants, fish hatcheries and oil refineries.
- Recording changes in water temperature can document thermal pollution.
The effects of thermal pollution can include:
- increased water temperatures
- increased plant growth
- slowing of river velocity because of planet growth
- fewer kinds of invertebrates
- large numbers of pollution tolerant invertebrates
- lower dissolved oxygen levels
Organic Nutrient Pollution
Too much of a good thing can be harmful to life. While nutrients are necessary - like nitrogen and phosphorus - too much can result in massive algae and plant growth. Excessive plant growth can be followed by oxygen depletion as dead plant material decomposes and bacteria uses oxygen. Lower oxygen levels can result in fish kills.
Organic nutrients can originate with human and livestock wastes, feedlots, meat packing plants, sewage and fertilizer runoff from yards and farms.
- Invertebrate data can be used along with testing nitrogen and phosphorus levels to measure of organic nutrient pollution.
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Sewage Outfall
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The effects of organic pollution can include:
- fewer kinds of invertebrates
- large numbers of pollution tolerant invertebrates
- an increase in collectors and scrapers such as caddisfly larvae or roundworms
- unpleasant odours
- rocks covered in algae
- excessive weed growth
- high concentrations of nitrogen and phosphorus
- lower oxygen levels
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