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Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering

CE5504 Surface Water Quality Modeling. Lab 6. Sediment-Water Exchange The Recovery of Shagawa Lake, Minnesota: Sediment Mediation. Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering. Contaminant Association with Particulate Matter. Biological Uptake. Abiotic Adsorption.

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Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering

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  1. CE5504 Surface Water Quality Modeling Lab 6. Sediment-Water Exchange The Recovery of Shagawa Lake, Minnesota: Sediment Mediation Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering

  2. Contaminant Association with Particulate Matter Biological Uptake Abiotic Adsorption

  3. Depositional Basins depositional basin Onondaga Lake, NY

  4. Diagenesis The sum total of processes that bring about changes in a sediment subsequent to deposition in water. Berner 1980

  5. Sediment Recycle (Internal Loads) deposition flux diagenesis – redox reactions

  6. Phosphorus Biogeochemistry oxic conditions; sparingly soluble anoxic conditions; highly soluble

  7. Seasonality in P Release

  8. Hypolimnetic P Accumulation

  9. Gas Vent Support Raft Support Cables Contact Chamber Air Line & Diffuser Ballast Engineered Remediation 1. Sediment Removal (Dredging) 2. Hypolimnetic Withdrawal 3. Chemical Inactivation 4. Artificial Circulation 5. Hypolimnetic Aeration 6. Sediment Oxidation

  10. Monitored Natural Recovery The Slow Eigenvalue for the water column old SS concentration new SS for the sediment time

  11. Pore Water Diffusion Burial Natural Recovery: diffusion and burial

  12. Weak Sorber td+3 td+5 td+10 td+20 td+30 Weak sorber log Kd ~ 2.5 td+50

  13. Strong Sorber td+3 td+5 td+10 td+20 td+30 Strong sorber log Kd ~ 6 td+50

  14. Diagenesis and Recovery – Part I

  15. Diagenesis and Recovery – Part II

  16. Diagenesis and Recovery – Part III

  17. outflow load 8 deposition release burial Modeling Sediment – Water Interactions

  18. The Product The Supplies The Limiting Nutrient Concept

  19. The Limiting Nutrient Controversy

  20. Shagawa Lake

  21. Shagawa Lake • eutrophic system • tertiary treatment installed in 1973 • load reduction of 80%

  22. Shagawa Lake The (un)response

  23. Shagawa Lake • A mathematical model predicted that the lake would reach equilibirium P levels of 12 ppb in ~1.5 years. • The fact that it didn’t was attributed to sediment P feedback, primarily during summer. • Modification of the model to accommodate sediment P release matches post-treatment P levels well and indicates that P release has not been diminished since treatment went on line. • Further recovery will depend on the time course of reductions in sediment feedback.

  24. Monitored Natural Recovery The Slow Eigenvalue for the water column old SS concentration new SS for the sediment time

  25. Monitored Natural Recovery The Slow Eigenvalue for the water column for the sediment

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