  The determined abundances of primordial $^4He$ and $^7Li$ provide a basis
with which to test the standard model of big bang nucleosynthesis in
conjunction with the other two light element isotopes $D$ and $^3He$, also
produced in the big bang. Overall, consistency in the standard big bang
nucleosynthesis model is best achieved for a baryon-to-photon ratio of
typically $3 \times 10^{-10}$ for which the primordial value of $D$ is five
times greater than the present observed abundance and about three times greater
than the pre-solar value. We consider various models for the chemical evolution
of the Galaxy to test the feasibility for the destruction of D without the
overproduction of $^3He$ and overall metallicity. Models which are capable of
achieving this goal include ones with a star formation rate proportional to the
gas mass fraction or an exponentially decreasing star formation rate. We
discuss the effect of parameters that govern the initial mass function and of
surviving fractions of $^3He$ in stars between one and three solar masses.
