Dredging Contaminated Sediments Should the Ashtabula River be dredged?

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Dredging Contaminated SedimentsShould the
Ashtabula River be dredged?
An Earth Systems Lesson Plan Developed by Jeremy
King
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Background Information

• When pollutants enter an aquatic ecosystem they
  can become mixed into the sediments. These
  pollutants can be toxic to living organisms.
• Toxins can accumulate in the tissues of
  organisms. As the toxins move up the food chain,
  higher order predators become at risk for
  developing reproductive disorders and may
  experience other serious health effects.
• Some scientists believe that dredging is the
  solution to removing toxins from the aquatic
  environment.
• Others believe that dredging causes more problems
  as toxins are re-suspended in the water column.
• What is the best solution? Is it so cut and
  dried?

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Learning Objectives

• Describe methods for removing contaminated
  sediments from the stream environment
• Model the processes of dredging contaminated
  sediments
• Evaluate data to determine the success of
  dredging
• Make decisions based on scientific data
• Develop a concept map

Earth Systems Understandings ESU 1 - Earth is a
unique planet of rare beauty and great value ESU
2 - Human activities affect Earth systems ESU 3
- Development of scientific thinking and
technology increases our ability to understand
and utilize Earth ESU 4 - The Earth system is
composed of interacting subsystems
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Activity IDredging Contaminated Sediments

• In groups, model three types of dredging
• Attempt to dredge without disturbing the water
  column
• Compare data to determine which method works the
  best

Hydraulic Dredge
Clam-Shell Dredge
Bucket Dredge
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Activity IIShould the Ashtabula River be Dredged?

• Evaluate data from the Black River dredging
  project
• Determine whether dredging was successful
• Decide whether dredging should be attempted in a
  similar river - Ashtabula
• Develop a concept map for the process of dredging

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References

• Report on Black River bullhead catfish tumors
  http//www.epa.gov/glnpo/sediment/Bullhead/report.
  html
• Ashtabula River report updating toxin
  information http//www.fws.gov/midwest/AshtabulaN
  RDA/
• Baumann, P. and Harshbarger, J. (1996). Decline
  in liver neoplasms in wild brown bullhead catfish
  after coking plant closes and environmental PAHs
  plummet. Environmental Health Perspectives.
  103(2)168-170
• Ohio EPA http//www.epa.state.oh.us/