This figure shows the correlation between the [N II] lines (sum of λ 6548 + λ 6583 relative to Hα) and the [S II] lines (sum of λ 6716 + λ 6731 relative to Hα) for confirmed SNRs in M83 and in three other nearby spiral galaxies: M31 (Galarza et al. 1999), M33 (Gordon et al. 1998), and M81 (Lee et al. 2015). The [N II] (and in a number of cases [S II]) lines are considerably stronger in the M83 objects than for the other galaxies, reflecting the high metallicity of M83. Furthermore, there is a large dispersion in the [N II]/Hα line ratios for the M83 objects, which likely indicates the effects of local enhancements in N abundance, where SNR shocks encounter circumstellar material that has been enriched due to pre-SN mass loss from the progenitors.