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Effective diffusion in soil

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Rosy
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Effective diffusion in soil

Dear USEtox Team,

it is possible to know the equation on which the formula 57 of the documentation manual is based.

Why is a coefficient of 1.5 used for volume fraction of gas phase and for volume fraction of water phase?

Thank you

USEtox Team
USEtox Team's picture
Effective diffusion coefficient

The equation for the effective diffusion coefficient of organic chemicals in soil is based on SimpleBox (see e.g. equation 111 in Brandes et al. 1996), where the exponents are empirically derived as further described e.g. in Chapter 7.6 of Mackay 2001 or Liu & Nie 2001.