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Science 9: Monitoring the Quanitiy of Chemicals in the Environment
Monitoring Water Quality
 Water quality is determined according to what the water is used for.
 Both Provincial and Federal Government guidelines for water quality in five categories
of water use:
◦ 1)
(
)
◦ 2)
◦ 3)
drinking water
◦ 4)
◦ 5) protection of
How do we Test Water Quality?
 Scientists and technicians make sure that these guidelines are being met by monitoring
water quality.
 They use
and
indicators
Biological Indicators
 Scientists use organisms that live in water to help determine water quality.
 These indicators include
, plants, worms,
plankton, protozoa, bacteria and
,
Microbiological Indicators:
 Microscopic organisms such as bacteria can cause serious health problems
 Water samples are taken to determine the
and
of microscopic organisms
 Examples:
(
Waterton Tragedy:
)
Aquatic Invertebrates:
 Some biological indicators of water quality show the
which may indicate
water
of pollution,
Example:
Invertebrate:
Vertebrae:
Aquatic Environments:
 If the
of the water in an aquatic ecosystem is
you will not find many fish or insects there
 The diversity of all organisms
as acidity
and dissolved oxygen decreases.
Chemical Factors Affects Organisms




Water in the environment is never completely pure
It contains many different
and inorganic compounds.
The concentration of these compounds affects water quality
The following are the most commonly monitored as indicators of water quality:
◦ A)
B) Acidity
◦ C) Heavy Metals
D)
◦ E)
F) Phosphorous
◦ G) Sodium Chloride
H) Magnesium sulfate
Measuring Chemicals in the Environment
 The concentration of chemicals in the environment is usually measured in parts per
million (
) or milligrams per liter(
)
PPM:
1) Calculate the salt concentration (in ppm) when you have dissolved 10 mg of salt into 250 g
of water (250 mL of water has a mass of 250 g).
Dissolved Oxygen
 Dissolved oxygen is
for the health of aquatic life
 An acceptable level of dissolved oxygen for aquatic life is between
and
 The level of dissolved oxygen in water depends on:
◦ Temperature:
◦
Turbulence due to wind or speed of moving water:
◦
Amount of photosynthesis by plants and algae in the water:
◦
The number of organisms using up the oxygen:
 Five milligrams per liter (
most organisms that live in lakes and streams
ppm
) of dissolved oxygen will support
Dissolved Oxygen (ppm or mg/L)
Invertebrates
Poor Quality (0-4 ppm)
Midge larvae , Leech, Mosquito
wriggler
Moderate Quality (5-8 ppm)
Freshwater clam, Dragonfly nymph,
Fairy shrimp ,Mayflies, Stoneflies
Good Quality (9-10 ppm)
Caddisfy larvae, Stonefly larvae,
Mayfly larvae and some worms
Try This:
 Estimate the oxygen levels in each sample by looking at the number of freshwater
invertebrates in the following samples.
(i) Site A sample: 3 midges, 3 caddis flies, 1 damsel fly, 1 leech
(ii) Site B sample: 4 crane flies, 5 dragonflies, 1 stonefly, 3 blackflies
(iii) Site C sample: 1 gilled snail, 5 mayflies, 2 crane flies, 1 crayfish
(iv) Site D sample: 3 midges, 4 leeches, 1 worm, 1 dragonfly
Phosphorous and Nitrogen Content
 One factor that can affect dissolved oxygen is an increase in phosphorous and nitrogen
in the water
Recall That…
 Fertilizer runoff increased phosphorus and nitrogen in water increased growth of
algae  grow/die dead organic matter bacteria eat bacteria increase use up
dissolved oxygenoxygen content decreases  aquatic life dies
Acidity
 Precipitation with a
is considered
acid rain or snow
 When acid precipitation falls on aquatic ecosystems the acidity in the water increases
and the diversity of living things decreases
Spring Acid Shock:
Heavy Metals: