  At low temperatures, the transport coefficients in the disordered electron
gas acquire quantum corrections as a result of the complex interplay of
disorder and interactions. The interaction corrections to the electric
conductivity have their origin in virtual processes with typical electronic
energies far exceeding the temperature. Here, we study interaction corrections
$\delta S$ to the thermopower $S$ of the two-dimensional disordered electron
gas with long-range Coulomb interactions. We show that while both real and
virtual processes contribute to these corrections, the real processes are
dominant and lead to a logarithmic temperature dependence of $\delta S/S$ with
$\delta S/S<0$.
