Chloride Salt Effects on Algal
Populations
And the Dangers that they Present
By:Brandon Perrotte
Grade 9
Central Catholic
2008
Introduction
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Chloride salts have potentially harmful effects on
algae.
These salts enter the ecosystem due to runoff. It
has been found that they can be corrosive and
harmful to the environment.
The chloride salts, when used cause the decrease
in population of thousands of organisms, especially
algae.
This could therefore affect the organisms that feed
off of the algae and could then disrupt the
environment.
Background Information:
Chloride Salts
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Chloride Salts are binary compounds of
chlorine. They can be corrosive and are
soluble in water.
The salts used in the experiment were
sodium, magnesium and calcium chloride.
Some solid chlorides can be decomposed
through the process of hydrolysis.
Environmental Effects and
Inhibitions of Chloride Salts
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We use sodium chloride, or common road salt, to
clear the ice from our streets to prevent accidents
and injury.
This act also induces runoff into small marine and
wildlife ecosystems. The runoff may contain salts
and other potentially harmful chemicals.
This could be harmful to thousands of small
organisms and their habitat. It might also produce
some toxicity effects to the water that we drink and
use for common practices such as brushing our
teeth and showering daily.
Past Studies of Chloride
Levels in Streams
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Minnesota passed laws restricting salt
use for its disruptive corrosion and for
the reduction of water pollution
Discriminative Algal Traits
Euglena
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It is a common protist .
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It is commonly cylindrical in
shape.
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The chloroplasts in euglena are
clear.
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They are used as a common
aspect of many algal
investigations.
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They are found in freshwater
bodies such as ponds most
commonly during warm
seasons.
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The algae can function without
sunlight by taking nutrients
from decomposed organisms.
Chlamydomonas
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Chlamydomonas are
unicellular flagellates.
The ion channels such as
channelrhodopsin are
activated by light.
They are found in small
freshwater bodies. This
algae is a common model
for many algal experiments.
Purpose
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The Purpose of this experiment was to
investigate the effects of chloride salt
concentrations on two different algal
populations.
Hypothesis
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Null- The tested algal populations
exposed to chloride salts will not vary
significantly in growth from the
controls.
Alternate- The tested algal populations
exposed to chloride salts will vary
significantly in growth from the
controls.
Materials and Methods
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Materials
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Borosilicate test tubes(72)
Spectrophotometer(1)
Fluorescent lamp(1)
A large container of spring water
2 containers of both euglena and
chlamydomonas.
5ml pipette
200 microliter pipette
Three containers of 10% stocks of sodium
chloride, magnesium chloride, and calcium
chloride.
0.22 micron syringe filter
15 mL sterile polystyrene conical tubes
Test Tube Racks(2)
One Sharpie marker
Micropipette and pipette tips
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General Experimentation
Six sets of test tubes were
filled with different
concentrations of water, algae,
and a variable. They were
placed in a test tube rack and
were given light by an
overhanging fluorescent lamp.
A spectrophotometer was
used to measure absorbance
(and indirect measure of
population size) and set at a
wavelength of 430 nm.
Procedure
1. 36 13x100mm borosilicate culture
tubes were placed in both test tube
racks.
2. 12 tubes were placed into each row.
3. Algae, spring water, and one of three
chloride salts were pipetted into the
experimental tubes as follows to
create the desired salt concentrations.
Procedure (Continued….)
4. The tubes in the racks were exposed to
light by a fluorescent lamp. The light
from the lamp evaporated a portion of
the solution. The water was replaced
carefully to keep a correct volume.
5. After mixing tubes by inversion, the
absorbance at 430 nm was recorded on
days 1, 3, 6, 9, 12 and 15.
Procedure (continued…)
0%
1%
4%
2mL
2mL
2mL
Spring Water 3mL
2.5mL
1mL
Salts
0mL
.5mL
2mL
Total Amount 5mL
5mL
5mL
Algae
Euglena Populations
0.45
A-0%
0.4
A-10%
0.35
A-40%
0.3
B-0%
0.25
B-10%
0.2
0.15
B-40%
0.1
C-0%
0.05
C-10%
Days of Experimentation
15
Da
y
12
Da
y
9
Da
y
6
Da
y
3
Da
y
1
0
Da
y
Absorbance at wavelength 430
0.5
C-40%
Chlamydomonas Absorbance
0.4
Absorbance at wavelength
430nm
0.35
0.3
0.25
0.2
0.15
0.1
0.05
Days of Experimentation
Day 15
Day 12
Day 9
Day 6
Day 3
Day 1
0
A0%
A10%
A40%
B0%
B10%
B40%
C0%
C10%
C40%
Percent Change in Absorbance: Euglena (Days 1-15)
Average Absorbance at
wavelength 430 nm
80
60
40
20
0%
0
-20
NaCl
MgCl
-40
-60
-80
-100
Variable in Use
CaCl
1%
4%
Percent Change in Absorbance: Chlamydomonas (Days 1-15)
Average Absorbance at wavelength 430
nm
20
10
0
-10
NaCl
MgCl
-20
-30
-40
-50
-60
Variable in Use
CaCl
0
%
1
%
4
%
ANOVA Two Factor with Replication (Euglena)
ANOVA
Source of
Variation
SS
df
MS
F
P-value
F crit
Sample
3064.466
1 3064.466 0.545799 0.467203 4.259677
Columns
15627.59
3 5209.197 0.927788 0.442461 3.008787
Interaction
4924.889
3
Within
134751.3
24 5614.639
Total
158368.3
31
1641.63 0.292384
0.83047 3.008787
ANOVA Two Factor with Replication (Chlamydomonas)
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Sample
3064.466
1
3064.466
0.545799
0.467203
4.259677
Columns
15627.59
3
5209.197
0.927788
0.442461
3.008787
Interaction
4924.889
3
1641.63
0.292384
0.83047
3.008787
Within
134751.3
24
5614.639
Total
158368.3
31
Conclusion
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The chloride salts had a negative long
term effect on both algal populations.
This may have been due to the
corrosive properties of the salts or it
may have been just the concentration
of the salt that killed the algae.
Conclusion (continued…)
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These results show that algal populations in
the environment are at a great risk of
decreasing in size because of the potential
misuse of chloride salts.
The communities at the greatest risks are
the ones near roadsides where road salts
are being used to clear ice for safety.
This effects many environmental organisms
and ultimately the ecosystem that the algae
make up.
Conclusion (continued…)
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It is concluded in this experiment that the decrease in the algal
populations was due to growth inhibition caused by chloride
salts.
The Results drawn from the ANOVA data analysis showed pvalues greater than .05 so the null hypothesis was rejected.
(An ANOVA was performed on the absorbance results of both
euglena and chlamydomonas.)
The Dunnett Test was also used to conclude results. The
information was drawn by a t-test in which the resulting critical
values were below the approved critical values of Dunnett’s
Test. The critical value was above .05 therefore the null
hypothesis was rejected.
Limitations and Extensions
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There were only four trials for each treatment.
Use more tubes to increase experiment length.
Use different concentrations to increase the
diversity of results.
Use a wider variety of chloride salts and algae.
The right amount of light was not precise as it was
not known how the algae would operate under
different amounts of light. Therefore light was used
at a random amount.
References
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“Chalmydomonas Reinhardtii.” Wikipedia.org. 12 Jan. 2008.
<http://en.wikipedia.org/wiki/Chlamydomonas_reinhardtii>
“Euglena.” Wikipedia.org. 12 Jan. 2008.
<http://en.wikipedia.org/wiki/Euglena>
“Road Salt Harmful to Roadside Vegetation.”
DailyTargum.com. 12 Jan. 2008.
http://media.www.dailytargum.com/media/storage/paper
168/news/2000/02/08/News/RoadSalt.Harmful.To.Roadside.Vegetation-105004.shtml
“Road Salt: Can we have safe roads and healthy streams?”
DuluthStreams.org. 12 Jan. 2008.
<http://duluthstreams.org/understanding/impact_salt.html>
References (cont.)
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Dr. John Wilson, biostatistician, University of Pittsburgh
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Sudhir, P. and Murthy, S.D.S. “Effects of salt stress on basic
processes of photosynthesis.” 22 Jan. 2008.
http://www.springerlink.com/content/j3g7906l71144566/
Batterton Jr. John C. and Van Baalen C. “Growth responses
of blue-green algae to sodium chloride concentration.”
22 Jan. 2008.
<http://www.springerlink.com/content/n2733738wm321m9
0/>
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