  Using a sample of 57,377 star-forming galaxies drawn from the Sloan Digital
Sky Survey, we study the relationship between gas-phase oxygen abundance and
environment in the local Universe. We find that there is a strong relationship
between metallicity and environment such that more metal-rich galaxies favor
regions of higher overdensity. Furthermore, this metallicity-density relation
is comparable in strength to the color-density relation along the blue cloud.
After removing the mean dependence of environment on color and luminosity, we
find a significant residual trend between metallicity and environment that is
largely driven by galaxies in high-density regions, such as groups and
clusters. We discuss the potential source of this relationship between
metallicity and local galaxy density in the context of feedback models, with
special attention paid to quantifying the impact of environment on the scatter
in the mass-metallicity relation. We find that environment is a non-negligible
source of scatter in this fundamental relation, with > 15% of the measured
scatter correlated with environment.
