Diatoms Used to Evaluate Wastewaters
Allison Starr, Dr. Marina Potapova, Dr. Lloyd Ackert
Drexel University, Department of Biodiversity, Earth, and Environmental Science; Drexel University, Department of History
Introduction
Diatoms, microscopic algae, can be used to evaluate the ecological health of
aquatic ecosystems. My goal was to conduct a study on four waterways in
western Pennsylvania that have been exposed to fracking wastewater effluent.
This is the first study of the effect of fracking wastewater on river diatoms. I
hypothesized that the community composition of the diatoms would indicate
polluted habitats.
Results
Conclusion
At the facility located on McKee Run, the relative abundance of diatom Achnanthidium pyrenaicum
increased at the effluent-affected site, but then decreased again downstream.
My results demonstrate that although the effect of the effluent was
evident at each of the four sites, it was weaker than the effect of the
other environmental factors that influence community composition, such
as conductivity.
Background
Conductivity can be influenced by other factors such as normal variation
in salt levels, nutrient concentrations, oxygen levels, and water
temperature (Ziemann 2011).
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The practice of using diatoms to monitor aquatic habitats was pioneered in
the United States by the late Doctor Ruth Patrick of the Academy of
Natural Sciences, who in 1948 conducted a biological assessment of
Conestoga Creek (now called the Conestoga River). During the course of my
scientific project with Doctor Potapova, I also researched Doctor Patrick’s
work from 1932 to 1946 with Doctor Lloyd Ackert.
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Future Work
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One way to detect a substances’ negative effect on the environment is to
look for teratologic diatoms. Teratologic diatoms possess “non-adaptive
[physical] abnormalities (Falasco et al. 2009).” The most common deformity
involves the valve outline. Copper, zinc, and cadmium have been known to
cause valves to swell. However, usually valve surface area decreases “due to
constrictions of the outline (Falasco and Badino, 2011).”
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The experiment is part of a larger project to evaluate the impact of the
wastewater effluent on the study sites. The results of this experiment, and
the project as a whole, will add to the body of evidence concerning
fracking’s impact on the environment.
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HD4 effluent
HD2 1 mi
downstream
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HD6 .08 mi
upstream
In the future, it would be ideal if members of the team identifying and
counting the diatoms journeyed to the wastewater treatment plants. That
way, the scientists would know the conditions of the sample areas.
At the facility located on Allegheny R. at Warren, the effect of the effluent was evident in the
increase of the relative abundance of two diatom species: Cocconeis placentula and Rhoicosphenia
abbreviatum.
From left: Navicula lanceolata, Diatoma moniliformis, teratologic D. tenuis, Fragilaria
vaucheriae, teratologic Fragilaria vaucheriae, Encyonema silesiacum, Achnanthidium
pyrenaicum, Amphora pediculus, Achnanthidium minutissimum
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WD1 .25 mi downstream
Methods
• Scientists from Dartmouth collected twenty-two
samples from four treatment facilities
• Samples from above, at, and below
effluent
• Recorded pH, conductivity, and
temperature
• Noted that conductivity
greatly increased
downstream
• I processed the samples with nitric acid and prepared
permanent slides with Naphrax
• I made a visual dictionary
• I counted and identified a hundred valves from each
slide
• I mainly used “Diatoms of the Untied
States
• I also used Diatomeen im SüßwasserBenthos von Mitteleuropa (Hofmann
2011) and Süßwasserflora von
Mitteleuropa (Krammer)
• I plotted the diatom abundances
• Doctor Potapova reviewed the counts and conducted
statistical analyses
Community composition changed due to the effluent’s toxicity, but the
communities showed signs of recovery downstream from the wastewater
treatment facilities.
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WD3 1 mi downstream
At the facility on Blacklick Creek, the relative abundance of diatoms Diatoma tenuis and D.
moniliformis declined at the effluent-affected site, then somewhat recovered downstream.
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1 mi downstream
0.2 mi downstream
I also plan to continue my historical research with Doctor Ackert. I have
already completed a rough draft of a paper concerning the previously
mentioned work of Doctor Patrick.
References
WD4 .5 mi upstream
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As information about the chemicals used in fracking is released, scientists
will be able to compare the effects of specific chemicals on diatoms.
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Falasco, Elisa, and Guido Badino. "The Role of Environmental Factors in Shaping Diatom
Frustule." Diatoms: Ecology and Life Cycle. Ed. James C. Compton. New York: Nova
Science Publishers, Inc., 2011. 1. Print.
Falasco, Elisa, et al. "Morphological Abnormalities of Diatom Silica Walls in Relation to
Heavy Metal Contamination and Artificial Growth Conditions." Water SA 35.5 (2009):
595. Web.
Ziemann, Horst, and Claus-Jürgen Schulz. "Methods for Biological Assessment of SaltLoaded Running Waters– Fundamentals, Current Positions and Perspectives."
Limnologica 41 (2011): 90. Web.
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upstream
effluent
Additionally, the researchers collected three samples from the Allegheny River at
Franklin, PA. Two samples were collected 0.2 miles above the effluent, and one
sample was collected in the effluent. The most common species upstream were
Navicula lanceolata, N. cryptotenella, Encyonema silesiacum, Nitzschia dissipata,
Amphora pediculus, and Cocconeis placentula. The most common species in the
effluent-affected site was Fragilaria vaucheriae.
Acknowledgements
I thank Marina Potapova and Lloyd Ackert for their guidance throughout this project. I
also thank Nina Desianti for laboratory assistance.