Water Chemistry
Take out your Homework, Get your game face
on, answer these questions in your notes…
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What 3 factors play a role
in determining the health of
an aquatic ecosystem?
What is your definition for
polluted water in your own
words?
Make a list of at least 8
things you believe pollute
water.
Water Quality
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Q: Water quality of
ecosystems is dependent on
what 3 categories?:
A: Chemical, Physical,
Biological
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Q: What is water pollution?
When substances in water are
harmful to the organisms
that live there, the water is
considered polluted.
What is Dissolved Oxygen?
(Chemical)
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Dissolved Oxygen is known as
“D.O.” This is the most
important chemical
requirement for aquatic
organisms.
Diffusion- Water mixes with
air when it falls over rocks and
waterfalls increasing the level
of D.O.
Video of Waterfall adding DO
Standing or slow moving
bodies of water have less D.O.
than fast moving water bodies.
Example
Which likely has more D.O. and why?
DO Continued
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Q: What 2 things increases D.O. in
water?
A: Photosynthesis increases D.O.
A: Diffusion
Q: What 2 things decreases D.O. in
water?
A: Respiration by aquatic animals
decreases it(remember C-O cycle?)
A: Water polluted with organic matter has
less D.O. than clean water because
decomposers of the organic matter use up
the D.O.
Most fish cannot live with D.O. less
than 5 ppm.
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Low- 0-5 ppm, Medium- 6-10 ppm, High- 11-15 ppm
What about the fish tank. What adds
DO, and what takes it away? At Night?
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Temperature (Physical)
Q: How does temperature have an effect on water?
A: As temp. increases, less D.O. can be held in water.
Example: Trout require high levels of D.O. which is
why they live in coldwater streams.
Example
Temperature Con’t
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Q: What is Thermal
Pollution?
It occurs when
industries (power
plants) use water for
cooling.
The hot water is
dumped into aquatic
systems raising the
temperature.
Q: Why does this harm
wildlife in the stream?
What type of plant is
this, and where does
the hot water come
from?
What is Turbidity? (Physical)
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It is the measure of the amount of light scattered
or absorbed by particles in water (cloudiness).
Q: What increases turbidity in water?
A: Eroded soil in water increases turbidity, clogs
fish gills, and smothers aquatic insects.
Which has more turbidity?
pH (Chemical)
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Few aquatic
organisms can live
in water with pH
lower than 4 or
higher than 9.
Best range: fish 6.7
- 8.6
What could you
infer if the only
species you found
in an environment
was the Water
Boatman?
Example
pH Continued
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Q: What are some things
(3) that change pH of
water?
CO2 produced from
decaying organisms forms
carbonic acid decreasing
pH.
Sulfuric acid in water comes
from acid mine drainage
and acid rain (burning fossil
fuels) decreasing pH.
Alkaline industrial waste
(bleaching plant) can
increase pH.
Hardness (Chemical)
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Water with many minerals is
considered hard.
Water containing calcium and
magnesium is said to be hard.
The minerals in hard water can
buffer acidic rain water.
Calcium is needed for clams,
snails, and other shelled
organisms.
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Soft: 0 - 60 ppm
Medium: 60 – 120 ppm
Hard: 120 – 180 ppm
Lets Read about Dead Zones
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Read the Article and Answer the questions on
Dead Zones in the Gulf of Mexico
Take out your HW…answer these questions!
•What are the 3 categories that affect water quality?
•What factor most affects water quality?
•Why is temperature so critical to an aquatic ecosystem?
•What takes DO out of a system? What adds it in?
•What is a wetland?
•What functions does a wetland serve?
•What is a watershed?
•What is water pollution?
What is happening to the
Chesapeake?
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Get Out Yo HW
Get out Yo Water Chemistry Notes
Watch the video and write down what things
(SEVERAL) are going wrong with the
Chesapeake…make sure to explain your
answers…
Video
Nitrites/Nitrate (Chemical)
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Runoff of fertilizers, animal
wastes, and sewage are the
major sources.
EUTROPHICATIONExcessive nitrogen causes
algae population to explode
(algae bloom).
Most nitrogen is constantly
used up in the system.
More than 1 ppm indicates
excess!
When the algae dies it
decomposes using up the
D.O.
Redtide at Night!!!
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Video: Surfing at Night with a bacterial Night
Light
Video: Bioluminescent Kayaking
Video: Bioluminescent Swimmers at Night
Phosphates (Chemical)
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Comes from the same
sources as nitrogen as well
as some industrial
processes.
Used in Laundry Detergent
Also causes algae blooms.
Not as harmful to humans
or animals as nitrogen.
More than 0.5 ppm
indicates excess.
Hurricane Floyd
2.5 billion gallons hog/poultry waste
Dead Zones