We present results of optical spectroscopy of 35 H II regions from eight dwarf galaxies in the Centaurus A group .
[ O III ] \lambda 4363 is detected in ESO272 - G025 and ESO324 - G024 , and direct oxygen abundances of 12 + log ( O/H ) = 7.76 \pm 0.09 and 7.94 \pm 0.11 are derived , respectively .
For the remaining galaxies , abundances are derived using common bright-line methods .
To compare the influence of group environments on dwarf galaxies , we have also gathered data for additional dwarf irregular galaxies from the Cen A and the Sculptor groups from the literature .
We have examined possible relationships between oxygen abundance , gas fraction , effective chemical yield , and tidal indices .
Despite large positive tidal indices for a number of Cen A dwarfs in the present sample , there is no clear separation between galaxies with positive tidal indices and galaxies with negative tidal indices in the luminosity-metallicity , metallicity-gas fraction , and metallicity-tidal index diagrams .
The H I surface mass density decreases with increasing positive tidal index , which is expected in strong tidal encounters .
There are no strong trends between oxygen abundances or yields and projected distances of galaxies within their respective groups .
We also present spectra for 13 H II regions in three nearby dwarf irregular galaxies : DDO 47 , NGC 3109 , and Sextans B .
For DDO 47 , the [ O III ] \lambda 4363 oxygen abundance ( 7.92 \pm 0.06 ) for the H II region SHK91 No .
18 agrees with recently published values .
For Sextans B , the [ O III ] \lambda 4363 oxygen abundance ( 7.80 \pm 0.13 ) for H II region SHK91 No .
5 agrees with published work in which O ^ { + } abundances were determined entirely from [ O II ] \lambda \lambda 7320 , 7330 fluxes .