Fugacity models level 1 equilibrium
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Fugacity Models Level 1: Equilibrium Level 2: Equilibrium between compartments & Steady-state over entire environment Level 3: Steady-State between compartments Level 4 : No steady-state or equilibrium / time dependent. Level 1: Equilibrium “Chemical properties control”

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Fugacity Models Level 1: Equilibrium

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Fugacity models level 1 equilibrium

Fugacity Models

Level 1: Equilibrium

Level 2: Equilibrium between compartments & Steady-state over entire environment

Level 3: Steady-State between compartments

Level 4 : No steady-state or equilibrium / time dependent


Fugacity models level 1 equilibrium

Level 1: Equilibrium

“Chemical properties control”

fugacity of chemical in medium 1 =

fugacity of chemical in medium 2 =

fugacity of chemical in medium 3 =

…..


Fugacity models level 1 equilibrium

Mass Balance

Total Mass = Sum (Ci.Vi)

Total Mass = Sum (fi.Zi.Vi)

At Equilibrium : fi are equal

Total Mass = M = f.Sum(Zi.Vi)

f = M/Sum (Zi.Vi)


Fugacity models level 1 equilibrium

Fugacity Models

Level 1: Equilibrium

Level 2: Equilibrium between compartments & Steady-state over entire environment

Level 3: Steady-State between compartments

Level 4 : No steady-state or equilibrium / time dependent


Fugacity models level 1 equilibrium

Level 2:

Steady-state over the entire environment & Equilibrium between compartment

Flux in = Flux out

fugacity of chemical in medium 1 =

fugacity of chemical in medium 2 =

fugacity of chemical in medium 3 =

…..


Fugacity models level 1 equilibrium

Level II fugacity Model:

Steady-state over the ENTIRE environment

Flux in = Flux out

E + GA.CBA + GW.CBW = GA.CA + GW.CW

All Inputs = GA.CA + GW.CW

All Inputs = GA.fA .ZA + GW.fW .ZW

Assume equilibrium between media : fA= fW

All Inputs = (GA.ZA + GW.ZW).f

f = All Inputs / (GA.ZA + GW.ZW)

f = All Inputs / Sum (all D values)


Fugacity models level 1 equilibrium

Fugacity Models

Level 1: Equilibrium

Level 2: Equilibrium between compartments & Steady-state over entire environment

Level 3: Steady-State between compartments

Level 4 : No steady-state or equilibrium / time dependent


Fugacity models level 1 equilibrium

Level III fugacity Model:

Steady-state in each compartment of the environment

Flux in = Flux out

Ei + Sum(Gi.CBi) + Sum(Dji.fj)= Sum(DRi + DAi + Dij.)fi

For each compartment, there is one equation & one unknown.

This set of equations can be solved by substitution and elimination, but this is quite a chore.

Use Computer


Fugacity models level 1 equilibrium

Time Dependent Fate Models / Level IV


Evaluative models vs real models

Evaluative Models vs. Real Models


Fugacity models level 1 equilibrium

Recipe for developing mass balance equations

1. Identify # of compartments

2. Identify relevant transport and transformation processes

3. It helps to make a conceptual diagram with arrows representing the relevant transport and transformation processes

4. Set up the differential equation for each compartment

5. Solve the differential equation(s) by assuming steady-state, i.e. Net flux is 0, dC/dt or df/dt is 0.

6. If steady-state does not apply, solve by numerical simulation


Fugacity models level 1 equilibrium

  • Application of the Models

  • To assess concentrations in the environment

  • (if selecting appropriate environmental conditions)

  • To assess chemical persistence in the environment

  • To determine an environmental distribution profile

  • To assess changes in concentrations over time.


Fugacity models level 1 equilibrium

What is the difference between

Equilibrium & Steady-State?


Fugacity models level 1 equilibrium

Time Dependent Fate Models / Level IV


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