Transcript GO 2_CB Monitoring Water Quality PPT

GO C2 Identify processes for Measuring the Quantity of Different Substances
in the Environment and for Monitoring air and water Quality.
2.1:Monitoring Water Quality
Guided Question
Why is it important to monitor the
quality of water?
Would you Drink this water?
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Monitoring: keeping track of something for a
specific purpose.
Water quality is determined by what water
is used for. It is regulated by technicians
Their are five categories of water use:
1.
2.
3.
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5.
Human drinking water
Recreation such as swimming
Livestock drinking water
Irrigation
Protection of aquatic life
Biological Indicators
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Scientist use organisms that live in the water to
help determine water quality.
Microbiological Indicators
 Microscopic organisms such as bacteria can
cause serious health problems if they are
present in high enough numbers.( E coli bacteria)
Aquatic Invertebrates
 Invertebrates are animals without backbones.
They are used for monitoring because different
invertebrates prefer different living conditions.
Examples of Indicators
Biological Indicators
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Which organisms indicate a high level of
dissolved O2? good water conditions
Which organisms indicate a low level of
dissolved O2? poor water conditions
Dissolved
Oxygen level
Consequences
Dissolved O2 Large variety of invertebrates (insect larvae,
8 Excellent beetles, worms) Many species of fish and other
desirable organisms
Dissolved O2 Few mayfly larvae, some stonefly larvae, some
beetles, many midge larvae, many worms including
6 Good
leeches
Dissolved O2 Freshwater shrimp, many midge larvae, many worms
including leeches. Some species have difficulty living
4 Low
in critical levels.
Dissolved O2 Many midge larvae, some worms including leeches
2 Very Low
Dissolved O2 No species of game fish exist, some midge larvae,
some worms
0 Critical
Chemical Factors that Affect Organisms
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Water found in our environment may contain many
different organic and inorganic compounds. The
concentration of these compounds affects water
quality.
The following are monitored as indicators of water
quality:
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Dissolved oxygen
Acidity
Heavy metals
Plant nutrients (such as nitrogen and phosphorus)
Pesticides
Salts (such as sodium chloride and magnesium sulfate)
Dissolved Oxygen
The level of dissolved oxygen
depends on:
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Temperature (due to change in
seasons)
Turbulence (due to wind or the
speed of moving water)
Photosynthesis of aquatic
plants or algae
# of organisms using up the
oxygen
Dissolved oxygen is essential
for the health of aquatic life.
Acidity
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Precipitation with a pH lower than 5.6 is considered
acid rain/snow.
Acid precipitation causes major problems in the
spring when the snow melts and flows into aquatic
systems. Spring acid shock causes serious harm to
the eggs and young offspring of fish.
As the acidity increases the diversity of organisms
decreases!
Most fish disappear if the water’s pH falls to 4.5.
Heavy Metals
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Heavy metals have a density of
5g/cm3 or higher
Include copper, zinc, lead, mercury,
cadmium and nickel
They naturally occur in rocks and soil
They are mined to make: batteries,
tires, paints, pipes, thermometers
and fertilizers
Heavy metals must be monitored
because they can be toxic to a
variety of organisms
Plant Nutrients
(Phosphorus and Nitrogen Content)
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Phosphorus and nitrogen are important
for all living things, but too much can
cause problems. Excess P and N2 comes
from:
Sewage outfalls
 Runoff from fertilized fields
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High amounts of P and N2 cause:
Increased growth in algae and green plants
Plants dies and becomes food for bacteria that
decompose it
Bacteria increase in number
Increased bacteria use up dissolved oxygen
Fish and aquatic insects cannot survive
Pesticides
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Some pesticides have long lasting effects as
they do not break down quickly and last in the
environment for a long period of time ( DDT)
Most are now used for ONE growing season
They do however create organisms that can
become RESISTANT to the pesticide
Larger numbers of pesticides are creating
problems in the environment as if they are
mixed together they create a TOXIC
substance
TOXICITY – describes how poisonous a
substance is
Measuring Toxicity
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Toxins or poisons are substances that produce
serious health problems or death when
introduced into an organism.
In order to compare toxins, a measurement
called LD50 is used.
LD stands for lethal dose; 50 represents
50%.
LD50 is the amount of a substance that
causes 50% of animals to die if they are given
a specified dose of the substance all at once.
Table salt – 3000mg/kg, Caffeine – 192 mg/kg,
DDT 87mg/kg (all given to rats by mouth)
Measuring Chemicals in the Environment
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The concentration of chemicals in the
environment is usually measured in parts
per million (ppm)
One part per million means that one unit
of an element can be found in one million
units of solution
Some times the concentrations are
expressed in parts per billion (ppb) or
parts per trillion (ppt)
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1 ppm is about the same as 1 drop of
food colouring in a half filled bath tub
1 ppb is about the same as 1 drop of
food colouring in a swimming pool
1 ppt is about the same as 1 drop of
food colouring in 1000 swimming pools
Determining ppm
ppm= Part (g or mL) ie. 1 Part per million
1 000 000 mL
millilitres
ppm = mg =
mg =
g or mL _
L 1 000mL 1 000 000mL
Example
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If there are 20 mg of oxygen dissolved
in 5 L of water, how many ppm of
dissolved oxygen is there?
ppm = 20 mg = 4 mg/L = 4 ppm
5L
Example 2
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If there is 5mL of oxygen dissolved in 995
mL of water, how many ppm of dissolved
oxygen is there?
ppm =
g or mL _
1 000 000mL
ppm = 5 mL = 0.005 mL/mL
1000mL
ppm = 0.005 = 5000 ppm
1000
Water Quality – Hot Topic
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http://www.youtube.com/watch?v=2igTexiW3
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Do you think it will be banned?
Do you think it should be?
Could it be a risk to humans?
Should it be used, even if not a risk to human?
Homework: can you find any triclosan in your
home?