Density dependent on temperature and solute concentration

Hello,

I am trying to couple fluid flow (Darcy's Law), temperature (Heat Transfer in Porous Media), and solute transport (Species Transport in Porous Media). I need the density of water to be dependent on temperature and solute concentration, but I am not sure how to modify the density term under the material properties.

For example, what would I add to this term to make the density dependent on concentration as well as temperature:
rho(T[1/K])[kg/m^3]

Thank-you for your help.