1. Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering CE5504 Surface Water Quality Modeling Lab 5. Sediment-Water Exchange The Recovery of Shagawa Lake, Minnesota: Sediment Mediation

2. Contaminant Association with Particulate Matter Biological Uptake Abiotic Adsorption

3. Onondaga Lake, NY depositional basin Depositional Basins

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

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

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

7. Seasonality in P Release

8. Hypolimnetic P Accumulation

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

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

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

12. Weak Sorber t d +3 t d +5 t d +10 t d +20 t d +30 t d +50 Weak sorber log K d ~ 2.5

13. Strong Sorber t d +3 t d +5 t d +10 t d +20 t d +30 t d +50 Strong sorber log K d ~ 6

14. Diagenesis and Recovery – Part I

15. Diagenesis and Recovery – Part II

16. Diagenesis and Recovery – Part III

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

18. The Limiting Nutrient Concept The Supplies The Product

19. The Limiting Nutrient Controversy

20. Shagawa Lake

21. 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.