Metal Abundances and Depletions in the Neutral Interstellar Medium of
  Galaxies: the Local Volume as a Laboratory
  The comparison of chemical abundances in the neutral gas of galaxies to
photospheric abundances of old and young stars, ionized gas abundances, and
abundances in galactic halos can trace the chemical enrichment of the universe
through cosmic times. In particular, our understanding of chemical enrichment
through spectroscopic observations of damped Lyman alpha systems (DLAs) relies
on corrections for depletion of metals from the gas to the dust phase. These
corrections must be determined in the nearby universe, where both gas-phase
abundances and photospheric abundances of young stars recently formed out of
the interstellar medium can be measured. Multi-object high-resolution
(R>50,000) ultraviolet (970-2400 A) and optical (300-600 nm) spectroscopy
toward massive stars in local volume galaxies (D < 15 Mpc) covering a wide
range of metallicities (a few % solar to solar) and morphological types will
provide the abundance and depletion measurements needed to obtain a detailed
and comprehensive characterization of the lifecycle of metals in neutral gas
and dust in galaxies, thereby observationally addressing important questions
about chemical enrichment and galaxy evolution.
