Soap Runoff Effects on Algal
Populations
Mike Trentadue
2008 PJAS
Central Catholic
Ground Runoff
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Ground runoff is part of the water
cycle and is when water runs across
land formations.
It is caused when rain and excess
water start to flow down hill.
During Ground Runoff the water can
carry many pollutants such as…
Pollutants
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Pesticides
Fertilizer
Litter
Oil and Gasoline Spills
Soap
Soaps
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Soaps are a mixture of chemicals to
form a cleaning agent that can be
used to clean various surfaces.
There are various types of soap
including Antibacterial and Non
Antibacterial.
The active ingredient in the soaps to
kill bacterial is Triclosan.
Algae
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There are many different kinds of
algae through out the world.
One of the most common being
Euglena.
Euglena
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Euglena is a common group of
freshwater single celled organisms
in the Kingdom Protista.
There are about 150 species of
Euglena.
They produce their own food
through photosynthesis.
Triclosan
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Triclosan has been shown to be
effective in reducing and controlling
bacterial contamination on the
hands.
Research has also show that the
presence of Triclosan may influence
the structure and function of algal
communities in stream ecosystems.
Purpose
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The purpose of this study is to find
out what kind of effect soap runoff
would have on the growth of
Euglena in our aquatic ecosystems.
My Hypotheses
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Null: The growth rate of the algae
contaminated with the higher
concentrations of soap WILL NOT exceed
the growth rate of the algae with the
lower soap concentrations.
Alternate: The growth rate of the algae
contaminated with higher concentrations
of soap WILL exceed the growth rate of
algae contaminated with the lower
concentrations of soap.
Materials
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Test Tubes- 16
Spring Water
Euglena – 34ml
Test Tube Racks – 4
Spectrophotometer – 1
200µl micro-pipette -1
10ml macro-pipette -1
5ml macro-pipette – 1
Palmolive Antibacterial Dish Soap – 1 Bottle
Palmolive Non-Antibacterial Dish Soap – 1
Bottle
4 Styrofoam Cups
Procedure
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First, stock solutions of each of the
soaps with 1 part soap and 9 parts
water were mixed.
Next the test tubes were made to
make 1% soap, 0.1% soap and 0%
soap with the following combinations.
Tubes
0% AB
0.1%
AB
1% AB
0%
Non-AB
.01%
NonAB
1%
NonAB
Spring Water
3 (ml) 2.95
2.5
3
2.95 2.5
Euglena
2 (ml) 2
2
2
2
2
Soap
Concentration
0 (ml) .05
.5
0
.05
.5
Total
5 (ml) 5
5
5
5
5
* AB = Antibacterial
*Repeat Table 4 Times
Procedure (continued)
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After filling the tubes as shown they were placed in a test
tube rack the racks were placed under a window which
received sufficient morning light.
Next, Spectrophotometer readings were taken every day
for 10 days at around 9 pm.
Soap Effects on Algal Populations
Absorbance
in 430 nm
Day
Percent Absorbance Change Per
Soap Concentration (Days 1-10)
350
300
P=.018
250
% Change in
Absorbance
200
P=.002
P=9.943
E-05
150
100
P=.034
50
0
AB 1% AB 0.1% Reg. 1%
Reg.
0.1%
Soap Concentrations
Control
Limitations
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Algae may not of been very healthy
at the start of the experiment.
The experiment could have been
repeated more times to have more
examples to test the hypothesis.
The experiment could have been
run for longer than 10 days.
Extensions
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To further test the hypothesis…
Algae that is know to be healthy could be
used.
The experiment could be tested more
times.
Collect data over a longer time span to
test long term effects.
A larger variety of soaps could be used to
show their own effects.
A variety of other algae species could be
used to show other effects.
Conclusions
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The hypothesis that stated the growth
rate of the algae contaminated with the
higher concentrations of soap WILL NOT
exceed the growth rate of the algae with
the lower soap concentrations was
REJECTED.
The null hypothesis was rejected because
the p values were < (less then) .05.
Conclusions (continued)
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The hypothesis that stated the growth
rate of the algae contaminated with
higher concentrations of soap WILL
exceed the growth rate of algae
contaminated with the lower
concentrations of soap was ACCEPTED.
The alternate hypothesis was accepted
because the null hypothesis was rejected
due the to the p value being < (less than)
.05.
References