1. Monitoring Water Quality
2.1
Monitoring Water Quality

2. A. Water Quality water that looks clean may not be clean
there are many toxic dissolved substances
monitoring water quality is an accurate way of keeping track of what is in water systems
there are two indicators used to monitor water quality: biological and chemical
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3. B. Biological Indicators
biological indicators alert scientists to potential environmental problems
the types of organisms that live in the water are an indication of conditions like the amount of dissolved oxygen and pH
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4. two main types of biological indicators are: 1.
microorganisms eg) bacteria 2.
aquatic invertebrates (animals without backbones) eg) shrimp, leeches, worms
high amounts of harmful bacteria like E. coli would result in water treatment being necessary
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5. C. Chemical Indicators
six types of chemical indicators can directly be measured: 1.
dissolved oxygen
(needed for animal cells) 2.
acidity
(if pH is less than 5.0, fish could die) 3.
heavy metals
(eg. copper, mercury) 4.
plant nutrients
(eg. potassium, nitrogen) 5.
(eg. DDT)
pesticides 6.
salts
(eg. NaCl, MgSO4)
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6. D. Measuring Concentration
the concentration of chemicals in the environment is usually measured in
parts per million (ppm) or milligrams per litre (mg/L)
it is calculated as follows:
1,000,000
(one million!)
solute volume (mL)
solution volume (mL)
ppm =
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7. Example
Calculate the concentration if 1 mL chlorine is dissolved to make 10,000 mL of solution.
1,000,000
solute volume (mL)
solution volume (mL)
ppm =
1 mL
10,000mL
ppm =
1,000,000 =
100 ppm
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8. E. Dissolved Oxygen oxygen dissolves in water by diffusion from air
dissolved oxygen is removed by: 1.
decomposition (rotting) of organic material 2.
cellular respiration (fish gills)
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9. level of dissolved O2(g) depends on 4 factors:1.
temperature 2.
wind/water turbulence 3.
amount of photosynthesis 4.
number of organisms
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10. F. Nitrogen and Phosphorus
plant growth is stimulated by nutrients such as nitrates and phosphates
increasing the concentration of these nutrients in water increases plant production
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11. plants eventually die and decomposers (bacteria) break down the dead plants and use up a lot of dissolved O2(g)
the invertebrate and fish populations start to die off and you are left with leeches, worms and mosquitoes
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12. G. Acidity
normal rain has a pH of 5.6 while acid rain can be much lower (3.0)
as pH goes down (more acidic) so does the amount of biodiversity
most fish die if pH goes below 4.5
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13. this can weaken the eggs of organisms and kill their young
acid can build up in snow and ice in the winter and then be released all at once in the spring…called spring acid shock
this can weaken the eggs of organisms and kill their young
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14. H. Heavy Metals
heavy metals are metals with a minimum density of 5 g/cm3
eg) lead, copper, mercury
occur naturally in small amounts
human activities like industries and farming tend to concentrate them in ecosystems
they harm the normal development of humans and other organisms
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15. I. Measuring Toxicity
scientists use a measurement called LD50 to measure toxicity
LD50 is the amount of a substance given all at once that causes 50% of a test group of animals to die
the more toxic the substance, the lower the LD 50 number
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16. Assignment worksheet 5 and 6