The Presence of Polycyclic Aromatic Hydrocarbons in water

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The Presence of Polycyclic Aromatic Hydrocarbons
in water

• By Siobhan Shay

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What is a PAH?

• PAHs are compounds with multiple aromatic rings
• They are the result of incomplete combustion of
  organic substances such as wood, oil, coal and
  garbage.
• As they do not dissolve readily in water they are
  usually found on the surface of water
• PAHs are considered by the health department to
  be a carcinogen, although not all PAHs have been
  classified as such

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Naphthalene and Phenanthrene

• Naphthalenes structure Two benzene rings
  attached to each other
• Phenanthrenes structure Three benzene rings
  attached to each other

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Background on the experiment

• Samples from the Red Cedar River in Michigan were
  collected
• Samples were tested for the presence of PAHs
  using internal standards

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The Red Cedar River Flow

• The Red Cedar River in Michigan runs through
  Lansing, East Lansing (MSU Campus), and other
  surrounding areas
• The Red Cedar is approximately 45 miles long
• There are 12 tributaries of the Red Cedar

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Red Cedar River Flow

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Red Cedar River History of Pollution

• The Red Cedar has a history of pollution dating
  back many years.
• Most recent data has only examined the E. coli
  levels in the water which have consistently been
  above standard levels.
• The river runs through farmland, urban, and
  suburban areas
• It has a reputation of being one of the
  dirtiest rivers in the Lansing area.

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Red Cedar River History of Pollution

• In 2002, there was a study published about
  pollution in the Red Cedar River in Jackson
  (Lansing area) and the effects of Johnson
  Controls Inc, an industrial business
• The results were well above acceptable levels of
  trichloroethylene, a neurotoxin, and
  Polychlorinated Biphenyls (PBCs)
• They have had a problem with JCIs pollution
  since 1985, but have yet (2002) to correct
  themselves

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What is currently being done about pollution?

• Because many rivers in Michigan run through
  industrial and rural areas, there is a great
  concern about pollution.
• To keep track of pollution levels, they have
  instituted a Watershed Initiative which monitors
  the levels of pollution in the water (mostly
  biological)

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Where were the water samples taken?

• The samples for this experiment were taken in
  Lansing, where the Red Cedar splits from the
  Grand River, and also in Williamston, downstream
  from the industries.
• Only two samples were taken due to the difficulty
  to get to the water legally and safely
• The picture is of the Red Cedar on MSU, and it is
  very difficult to get a sample

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The Experiment

• There was unfortunately no information on the
  previously detected levels of PAHs available.
• The two PAHs investigated were Naphthalene, and
  Phenanthrene
• The detection levels in water from previous
  experiments in other natural water sources were
  in the parts per billion, so internal standards
  needed to be used

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Naphthalene

• The maximum absorption of Naphthalene is 270nm
• In order to prepare a standard curve, a stock
  solution of 100ppm was made
• Serial dilutions of 100, 75, 65 and 60 ppm were
  prepared for analysis.

• Solutions lower than 60ppm were unreadable
  because the concentrations were too low to be
  effectively used.
• Naphthalene had to be dissolved in acetone, added
  to water and forced into solution through heating

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Naphthalene The standard curve
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Naphthalene The results

• For this experiment, 65ppm of a Naphthalene
  solution was added to each sample
• When the unknowns were entered into the standard
  curve equation, the results were
• Lansing location 9.1ppm
• Williamston location 9.98ppm
• For each of these samples, the amount of
  Naphthalene (ppms) added was subtracted from the
  final amount

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Phenanthrene

• Phenanthrene was easier to detect in water.
• The lowest concentration for the standard curve
  we obtained was 25ppm for accurate results
• Phenanthrene was dissolved in acetone, added to
  water, and then forced into solution through
  heating
• The stock solution was 100ppm
• The serial dilutions were 100, 75, 50, and 25ppm
• The maximum absorption of Phenanthrene is 340pm

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Phenanthrene The standard curve
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Phenanthrene The results

• For these samples, 50ppm of a Phenanthrene
  solution was added to each sample
• The results were
• Lansing location 20.707ppm
• Williamston location 25.349ppm
• For each sample the amount added was subtracted
  from the final answer

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The results continued

• There was a pattern established between the two
  sources
• Water found upstream (Lansing) contained less
  pollutants than the water found downstream
  (Williamston)
• This agrees with predicted results because there
  is more opportunity to be contaminated the longer
  the water travels.

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What does this mean?

• The results of this experiment was surprising.
  The levels of the contaminants were much higher
  than the normal levels of detection
• The normal levels of detection are 100-5,000ppb.
• Phenanthrene was the most surprising with four to
  five times the normal range.
• Napthalene showed levels closer to the normal
  ranges, but were still almost twice as high.

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What does this mean?

• The source of these contaminants are unknown. We
  do know that the river flows through
  industrialized areas, and could have been caused
  by the mishandling of chemical waste from the
  industrial plants, the accumulation of car
  exhaust, or the burning of organic materials.
• There is know way at this time to determine a
  definite cause.

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Future plans for this experiment

• Due to time constraints, I was not able to
  complete the research as desired.
• In the future, it would be ideal to have more
  water samples from different places along the
  river.
• Also, a larger variety of analytes to
  investigate, rather than the two, would be ideal.
• Finally, the repetition of the experiment to
  solidify results would be desired.

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References

• www.msu-water.msu.edu
• www.ingham.org
• www.atsdr.cdc.gov