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Environmental Toxicology and Chemistry

Environmental Toxicology and Chemistry. Predicting Environmental Fate and Effects I. Predicting Environmental Fate and Effects I. Predicting Environmental Transport. Linear free energy relations: Δ G = Δ H – T Δ S. A Review on Equilibrium Partitioning. Equilibrium Partitioning.

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Environmental Toxicology and Chemistry

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  1. Environmental Toxicologyand Chemistry Predicting Environmental Fate and Effects I

  2. Predicting Environmental Fate and Effects I

  3. Predicting Environmental Transport • Linear free energy relations: • ΔG = ΔH – T ΔS

  4. A Review on Equilibrium Partitioning

  5. Equilibrium Partitioning • C1/C2 = K12

  6. Air-Water Partitioning • Kair-water = H = C air Cwater • H’ = P air Cwater

  7. Lipid-Water Partitioning • KFW = ƒlipid Kow • A plot of KFW versus Kow yields a slope of 0.048 ~ 5% lipid content in fish. • Based on the premise that the system has reached equilibrium.

  8. Particle-Water Partitioning • Kp = Cs Cw • Kp = ƒoc Koc • Kp = ƒoc Koc = ƒoc0.41Kow • Kp = Cs= ƒoc 0.41Kow Cw • Cw = Cs ƒoc 0.41 Kow

  9. Octanol-Water Partition Coefficients

  10. Estimating Kow

  11. Estimating Kow

  12. Bioconcentration Factors

  13. Bioconcentration Factors

  14. Bioconcentration Factors

  15. BCF in mammals

  16. Biotransfer Factor

  17. Aqueous Solubility

  18. Volatilization

  19. Soil Sorption Coefficients

  20. Transformation Reactions

  21. Reversible Reactions • Ionization • HA + H2O = H3O+ + A- • Ka = [H3O+] [A-] [HA]

  22. Precipitation and Dissolution • CuS(s) + H+ = Cu2+ + HS- • Ksp = [Cu2+] [HS-] [H+]

  23. Complexation and Chemical Speciation • Chemicals undergo ionic or covalent interactions that lead to the formation of different chemical species = speciation. • Formation of a series of metal-ligand complexes. • Cu2+ complexed to chelating agents will result in a reduction of its toxicity.

  24. References • 1-Crosby, D.G. Environmental Toxicology and Chemistry. 2000. Oxford University Press, New York. • 2- Shea, D. Transport and Fate of Toxicants in the Environment. In: Hodgson and Levi (Eds), A Textbook of Modern Toxicology, Second Edition, Appleton and Lange, 1997.

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