Why does the thermal conductivity of water decrease with increasing salinity? Intuitively I would expect the thermal and electric conductivity to be positively related, and since electric conductivity increases with salinity, so should thermal. But according to this table (p.10) it decreases. Why is this?
Related: is there such a thing as the Wiedemann-Franz law for liquids like water?
There's a paper that has theoretical derivations about it, but it's nowhere to be found:
Predvoditelev, A. S., "Some invariant Quantities in the Theories of Heat Conductance and the Viscosity of Liquids," Russian Journal of Physical Chemistry, Vol. 22, p. 339 (1948)
 A: (add my comment as an answer)
A short answer would be that although electric and thermal conductivity have (movement of free) electrons as their primary carriers, they operate on different ranges/frequencies/wavelengths, and as such the structure and energy zones of the material (or material compound) can have quite different factors for each type of conductance.
From the Wikipedia article on thermal conductivity:

In metals, thermal conductivity approximately tracks electrical
  conductivity according to the Wiedemann–Franz law, as freely moving
  valence electrons transfer not only electric current but also heat
  energy. However, the general correlation between electrical and
  thermal conductance does not hold for other materials, due to the
  increased importance of phonon carriers for heat in non-metals. Highly
  electrically conductive silver is less thermally conductive than
  diamond, which is an electrical insulator, but due to its orderly
  array of atoms it is conductive of heat via phonons

